Refactor config package

- Parse configuration only once during startup time
- Store configuration values in a global variable

6 files changed, 807 insertions, 504 deletions

diff --git a/config/config.go b/config/config.go
index 99afaef..53bd708 100644
--- a/config/config.go
+++ b/config/config.go
@@ -4,271 +4,11 @@
 
 package config // import "miniflux.app/config"
 
-import (
-	"net/url"
-	"os"
-	"strconv"
-	"strings"
+// Opts contains configuration options after parsing.
+var Opts *Options
 
-	"miniflux.app/logger"
-)
-
-const (
-	defaultBaseURL            = "http://localhost"
-	defaultDatabaseURL        = "user=postgres password=postgres dbname=miniflux2 sslmode=disable"
-	defaultWorkerPoolSize     = 5
-	defaultPollingFrequency   = 60
-	defaultBatchSize          = 10
-	defaultDatabaseMaxConns   = 20
-	defaultDatabaseMinConns   = 1
-	defaultArchiveReadDays    = 60
-	defaultListenAddr         = "127.0.0.1:8080"
-	defaultCertFile           = ""
-	defaultKeyFile            = ""
-	defaultCertDomain         = ""
-	defaultCertCache          = "/tmp/cert_cache"
-	defaultCleanupFrequency   = 24
-	defaultProxyImages        = "http-only"
-	defaultOAuth2ClientID     = ""
-	defaultOAuth2ClientSecret = ""
-	defaultOAuth2RedirectURL  = ""
-	defaultOAuth2Provider     = ""
-)
-
-// Config manages configuration parameters.
-type Config struct {
-	IsHTTPS  bool
-	baseURL  string
-	rootURL  string
-	basePath string
-}
-
-func (c *Config) parseBaseURL() {
-	baseURL := os.Getenv("BASE_URL")
-	if baseURL == "" {
-		return
-	}
-
-	if baseURL[len(baseURL)-1:] == "/" {
-		baseURL = baseURL[:len(baseURL)-1]
-	}
-
-	u, err := url.Parse(baseURL)
-	if err != nil {
-		logger.Error("Invalid BASE_URL: %v", err)
-		return
-	}
-
-	scheme := strings.ToLower(u.Scheme)
-	if scheme != "https" && scheme != "http" {
-		logger.Error("Invalid BASE_URL: scheme must be http or https")
-		return
-	}
-
-	c.baseURL = baseURL
-	c.basePath = u.Path
-
-	u.Path = ""
-	c.rootURL = u.String()
-}
-
-// HasDebugMode returns true if debug mode is enabled.
-func (c *Config) HasDebugMode() bool {
-	return getBooleanValue("DEBUG")
-}
-
-// BaseURL returns the application base URL with path.
-func (c *Config) BaseURL() string {
-	return c.baseURL
-}
-
-// RootURL returns the base URL without path.
-func (c *Config) RootURL() string {
-	return c.rootURL
-}
-
-// BasePath returns the application base path according to the base URL.
-func (c *Config) BasePath() string {
-	return c.basePath
-}
-
-// DatabaseURL returns the database URL.
-func (c *Config) DatabaseURL() string {
-	value, exists := os.LookupEnv("DATABASE_URL")
-	if !exists {
-		logger.Info("The environment variable DATABASE_URL is not configured (the default value is used instead)")
-	}
-
-	if value == "" {
-		value = defaultDatabaseURL
-	}
-
-	return value
-}
-
-// DatabaseMaxConns returns the maximum number of database connections.
-func (c *Config) DatabaseMaxConns() int {
-	return getIntValue("DATABASE_MAX_CONNS", defaultDatabaseMaxConns)
-}
-
-// DatabaseMinConns returns the minimum number of database connections.
-func (c *Config) DatabaseMinConns() int {
-	return getIntValue("DATABASE_MIN_CONNS", defaultDatabaseMinConns)
-}
-
-// ListenAddr returns the listen address for the HTTP server.
-func (c *Config) ListenAddr() string {
-	if port := os.Getenv("PORT"); port != "" {
-		return ":" + port
-	}
-
-	return getStringValue("LISTEN_ADDR", defaultListenAddr)
-}
-
-// CertFile returns the SSL certificate filename if any.
-func (c *Config) CertFile() string {
-	return getStringValue("CERT_FILE", defaultCertFile)
-}
-
-// KeyFile returns the private key filename for custom SSL certificate.
-func (c *Config) KeyFile() string {
-	return getStringValue("KEY_FILE", defaultKeyFile)
-}
-
-// CertDomain returns the domain to use for Let's Encrypt certificate.
-func (c *Config) CertDomain() string {
-	return getStringValue("CERT_DOMAIN", defaultCertDomain)
-}
-
-// CertCache returns the directory to use for Let's Encrypt session cache.
-func (c *Config) CertCache() string {
-	return getStringValue("CERT_CACHE", defaultCertCache)
-}
-
-// CleanupFrequency returns the interval for cleanup jobs.
-func (c *Config) CleanupFrequency() int {
-	return getIntValue("CLEANUP_FREQUENCY", defaultCleanupFrequency)
-}
-
-// WorkerPoolSize returns the number of background worker.
-func (c *Config) WorkerPoolSize() int {
-	return getIntValue("WORKER_POOL_SIZE", defaultWorkerPoolSize)
-}
-
-// PollingFrequency returns the interval to refresh feeds in the background.
-func (c *Config) PollingFrequency() int {
-	return getIntValue("POLLING_FREQUENCY", defaultPollingFrequency)
-}
-
-// BatchSize returns the number of feeds to send for background processing.
-func (c *Config) BatchSize() int {
-	return getIntValue("BATCH_SIZE", defaultBatchSize)
-}
-
-// IsOAuth2UserCreationAllowed returns true if user creation is allowed for OAuth2 users.
-func (c *Config) IsOAuth2UserCreationAllowed() bool {
-	return getBooleanValue("OAUTH2_USER_CREATION")
-}
-
-// OAuth2ClientID returns the OAuth2 Client ID.
-func (c *Config) OAuth2ClientID() string {
-	return getStringValue("OAUTH2_CLIENT_ID", defaultOAuth2ClientID)
-}
-
-// OAuth2ClientSecret returns the OAuth2 client secret.
-func (c *Config) OAuth2ClientSecret() string {
-	return getStringValue("OAUTH2_CLIENT_SECRET", defaultOAuth2ClientSecret)
-}
-
-// OAuth2RedirectURL returns the OAuth2 redirect URL.
-func (c *Config) OAuth2RedirectURL() string {
-	return getStringValue("OAUTH2_REDIRECT_URL", defaultOAuth2RedirectURL)
-}
-
-// OAuth2Provider returns the name of the OAuth2 provider configured.
-func (c *Config) OAuth2Provider() string {
-	return getStringValue("OAUTH2_PROVIDER", defaultOAuth2Provider)
-}
-
-// HasHSTS returns true if HTTP Strict Transport Security is enabled.
-func (c *Config) HasHSTS() bool {
-	return !getBooleanValue("DISABLE_HSTS")
-}
-
-// RunMigrations returns true if the environment variable RUN_MIGRATIONS is not empty.
-func (c *Config) RunMigrations() bool {
-	return getBooleanValue("RUN_MIGRATIONS")
-}
-
-// CreateAdmin returns true if the environment variable CREATE_ADMIN is not empty.
-func (c *Config) CreateAdmin() bool {
-	return getBooleanValue("CREATE_ADMIN")
-}
-
-// PocketConsumerKey returns the Pocket Consumer Key if defined as environment variable.
-func (c *Config) PocketConsumerKey(defaultValue string) string {
-	return getStringValue("POCKET_CONSUMER_KEY", defaultValue)
-}
-
-// ProxyImages returns "none" to never proxy, "http-only" to proxy non-HTTPS, "all" to always proxy.
-func (c *Config) ProxyImages() string {
-	return getStringValue("PROXY_IMAGES", defaultProxyImages)
-}
-
-// HasHTTPService returns true if the HTTP service is enabled.
-func (c *Config) HasHTTPService() bool {
-	return !getBooleanValue("DISABLE_HTTP_SERVICE")
-}
-
-// HasSchedulerService returns true if the scheduler service is enabled.
-func (c *Config) HasSchedulerService() bool {
-	return !getBooleanValue("DISABLE_SCHEDULER_SERVICE")
-}
-
-// ArchiveReadDays returns the number of days after which marking read items as removed.
-func (c *Config) ArchiveReadDays() int {
-	return getIntValue("ARCHIVE_READ_DAYS", defaultArchiveReadDays)
-}
-
-// NewConfig returns a new Config.
-func NewConfig() *Config {
-	cfg := &Config{
-		baseURL: defaultBaseURL,
-		rootURL: defaultBaseURL,
-		IsHTTPS: getBooleanValue("HTTPS"),
-	}
-
-	cfg.parseBaseURL()
-	return cfg
-}
-
-func getBooleanValue(key string) bool {
-	value := strings.ToLower(os.Getenv(key))
-	if value == "1" || value == "yes" || value == "true" || value == "on" {
-		return true
-	}
-	return false
-}
-
-func getStringValue(key, fallback string) string {
-	value := os.Getenv(key)
-	if value == "" {
-		return fallback
-	}
-
-	return value
-}
-
-func getIntValue(key string, fallback int) int {
-	value := os.Getenv(key)
-	if value == "" {
-		return fallback
-	}
-
-	v, err := strconv.Atoi(value)
-	if err != nil {
-		return fallback
-	}
-
-	return v
+// ParseConfig parses configuration options.
+func ParseConfig() (err error) {
+	Opts, err = parse()
+	return err
 }
diff --git a/config/config_test.go b/config/config_test.go
index dc6112e..0e691fc 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -1,4 +1,4 @@
-// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Copyright 2019 Frédéric Guillot. All rights reserved.
 // Use of this source code is governed by the Apache 2.0
 // license that can be found in the LICENSE file.
 
@@ -9,198 +9,125 @@ import (
 	"testing"
 )
 
-func TestGetBooleanValueWithUnsetVariable(t *testing.T) {
-	os.Clearenv()
-	if getBooleanValue("MY_TEST_VARIABLE") {
-		t.Errorf(`Unset variables should returns false`)
-	}
-}
-
-func TestGetBooleanValue(t *testing.T) {
-	scenarios := map[string]bool{
-		"":        false,
-		"1":       true,
-		"Yes":     true,
-		"yes":     true,
-		"True":    true,
-		"true":    true,
-		"on":      true,
-		"false":   false,
-		"off":     false,
-		"invalid": false,
-	}
-
-	for input, expected := range scenarios {
-		os.Clearenv()
-		os.Setenv("MY_TEST_VARIABLE", input)
-		result := getBooleanValue("MY_TEST_VARIABLE")
-		if result != expected {
-			t.Errorf(`Unexpected result for %q, got %v instead of %v`, input, result, expected)
-		}
-	}
-}
-
-func TestGetStringValueWithUnsetVariable(t *testing.T) {
-	os.Clearenv()
-	if getStringValue("MY_TEST_VARIABLE", "defaultValue") != "defaultValue" {
-		t.Errorf(`Unset variables should returns the default value`)
-	}
-}
-
-func TestGetStringValue(t *testing.T) {
+func TestDebugModeOn(t *testing.T) {
 	os.Clearenv()
-	os.Setenv("MY_TEST_VARIABLE", "test")
-	if getStringValue("MY_TEST_VARIABLE", "defaultValue") != "test" {
-		t.Errorf(`Defined variables should returns the specified value`)
-	}
-}
+	os.Setenv("DEBUG", "1")
 
-func TestGetIntValueWithUnsetVariable(t *testing.T) {
-	os.Clearenv()
-	if getIntValue("MY_TEST_VARIABLE", 42) != 42 {
-		t.Errorf(`Unset variables should returns the default value`)
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
 	}
-}
 
-func TestGetIntValueWithInvalidInput(t *testing.T) {
-	os.Clearenv()
-	os.Setenv("MY_TEST_VARIABLE", "invalid integer")
-	if getIntValue("MY_TEST_VARIABLE", 42) != 42 {
-		t.Errorf(`Invalid integer should returns the default value`)
+	if !opts.HasDebugMode() {
+		t.Fatalf(`Unexpected debug mode value, got "%v"`, opts.HasDebugMode())
 	}
 }
 
-func TestGetIntValue(t *testing.T) {
-	os.Clearenv()
-	os.Setenv("MY_TEST_VARIABLE", "2018")
-	if getIntValue("MY_TEST_VARIABLE", 42) != 2018 {
-		t.Errorf(`Defined variables should returns the specified value`)
-	}
-}
-
-func TestDebugModeOn(t *testing.T) {
+func TestDebugModeOff(t *testing.T) {
 	os.Clearenv()
-	os.Setenv("DEBUG", "1")
-	cfg := NewConfig()
 
-	if !cfg.HasDebugMode() {
-		t.Fatalf(`Unexpected debug mode value, got "%v"`, cfg.HasDebugMode())
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
 	}
-}
-
-func TestDebugModeOff(t *testing.T) {
-	os.Clearenv()
-	cfg := NewConfig()
 
-	if cfg.HasDebugMode() {
-		t.Fatalf(`Unexpected debug mode value, got "%v"`, cfg.HasDebugMode())
+	if opts.HasDebugMode() {
+		t.Fatalf(`Unexpected debug mode value, got "%v"`, opts.HasDebugMode())
 	}
 }
 
 func TestCustomBaseURL(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BASE_URL", "http://example.org")
-	cfg := NewConfig()
 
-	if cfg.BaseURL() != "http://example.org" {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
 	}
 
-	if cfg.RootURL() != "http://example.org" {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
+	if opts.BaseURL() != "http://example.org" {
+		t.Fatalf(`Unexpected base URL, got "%s"`, opts.BaseURL())
 	}
 
-	if cfg.BasePath() != "" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	if opts.RootURL() != "http://example.org" {
+		t.Fatalf(`Unexpected root URL, got "%s"`, opts.RootURL())
+	}
+
+	if opts.BasePath() != "" {
+		t.Fatalf(`Unexpected base path, got "%s"`, opts.BasePath())
 	}
 }
 
 func TestCustomBaseURLWithTrailingSlash(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BASE_URL", "http://example.org/folder/")
-	cfg := NewConfig()
 
-	if cfg.BaseURL() != "http://example.org/folder" {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
 	}
 
-	if cfg.RootURL() != "http://example.org" {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
+	if opts.BaseURL() != "http://example.org/folder" {
+		t.Fatalf(`Unexpected base URL, got "%s"`, opts.BaseURL())
 	}
 
-	if cfg.BasePath() != "/folder" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	if opts.RootURL() != "http://example.org" {
+		t.Fatalf(`Unexpected root URL, got "%s"`, opts.RootURL())
+	}
+
+	if opts.BasePath() != "/folder" {
+		t.Fatalf(`Unexpected base path, got "%s"`, opts.BasePath())
 	}
 }
 
 func TestBaseURLWithoutScheme(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BASE_URL", "example.org/folder/")
-	cfg := NewConfig()
-
-	if cfg.BaseURL() != "http://localhost" {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
-	}
-
-	if cfg.RootURL() != "http://localhost" {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
-	}
 
-	if cfg.BasePath() != "" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	_, err := parse()
+	if err == nil {
+		t.Fatalf(`Parsing must fail`)
 	}
 }
 
 func TestBaseURLWithInvalidScheme(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BASE_URL", "ftp://example.org/folder/")
-	cfg := NewConfig()
-
-	if cfg.BaseURL() != "http://localhost" {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
-	}
 
-	if cfg.RootURL() != "http://localhost" {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
-	}
-
-	if cfg.BasePath() != "" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	_, err := parse()
+	if err == nil {
+		t.Fatalf(`Parsing must fail`)
 	}
 }
 
 func TestInvalidBaseURL(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BASE_URL", "http://example|org")
-	cfg := NewConfig()
-
-	if cfg.BaseURL() != defaultBaseURL {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
-	}
-
-	if cfg.RootURL() != defaultBaseURL {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
-	}
 
-	if cfg.BasePath() != "" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	_, err := parse()
+	if err == nil {
+		t.Fatalf(`Parsing must fail`)
 	}
 }
 
 func TestDefaultBaseURL(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
 
-	if cfg.BaseURL() != defaultBaseURL {
-		t.Fatalf(`Unexpected base URL, got "%s"`, cfg.BaseURL())
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
 	}
 
-	if cfg.RootURL() != defaultBaseURL {
-		t.Fatalf(`Unexpected root URL, got "%s"`, cfg.RootURL())
+	if opts.BaseURL() != defaultBaseURL {
+		t.Fatalf(`Unexpected base URL, got "%s"`, opts.BaseURL())
 	}
 
-	if cfg.BasePath() != "" {
-		t.Fatalf(`Unexpected base path, got "%s"`, cfg.BasePath())
+	if opts.RootURL() != defaultBaseURL {
+		t.Fatalf(`Unexpected root URL, got "%s"`, opts.RootURL())
+	}
+
+	if opts.BasePath() != "" {
+		t.Fatalf(`Unexpected base path, got "%s"`, opts.BasePath())
 	}
 }
 
@@ -208,9 +135,13 @@ func TestDatabaseURL(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DATABASE_URL", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.DatabaseURL()
+	result := opts.DatabaseURL()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_URL value, got %q instead of %q`, result, expected)
@@ -219,9 +150,14 @@ func TestDatabaseURL(t *testing.T) {
 
 func TestDefaultDatabaseURLValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.DatabaseURL()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultDatabaseURL
+	result := opts.DatabaseURL()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_URL value, got %q instead of %q`, result, expected)
@@ -231,22 +167,30 @@ func TestDefaultDatabaseURLValue(t *testing.T) {
 func TestDefaultDatabaseMaxConnsValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultDatabaseMaxConns
-	result := cfg.DatabaseMaxConns()
+	result := opts.DatabaseMaxConns()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_MAX_CONNS value, got %v instead of %v`, result, expected)
 	}
 }
 
-func TestDeatabaseMaxConns(t *testing.T) {
+func TestDatabaseMaxConns(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DATABASE_MAX_CONNS", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.DatabaseMaxConns()
+	result := opts.DatabaseMaxConns()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_MAX_CONNS value, got %v instead of %v`, result, expected)
@@ -256,9 +200,13 @@ func TestDeatabaseMaxConns(t *testing.T) {
 func TestDefaultDatabaseMinConnsValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultDatabaseMinConns
-	result := cfg.DatabaseMinConns()
+	result := opts.DatabaseMinConns()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_MIN_CONNS value, got %v instead of %v`, result, expected)
@@ -269,9 +217,13 @@ func TestDatabaseMinConns(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DATABASE_MIN_CONNS", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.DatabaseMinConns()
+	result := opts.DatabaseMinConns()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DATABASE_MIN_CONNS value, got %v instead of %v`, result, expected)
@@ -282,9 +234,13 @@ func TestListenAddr(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("LISTEN_ADDR", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.ListenAddr()
+	result := opts.ListenAddr()
 
 	if result != expected {
 		t.Fatalf(`Unexpected LISTEN_ADDR value, got %q instead of %q`, result, expected)
@@ -296,9 +252,13 @@ func TestListenAddrWithPortDefined(t *testing.T) {
 	os.Setenv("PORT", "3000")
 	os.Setenv("LISTEN_ADDR", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := ":3000"
-	result := cfg.ListenAddr()
+	result := opts.ListenAddr()
 
 	if result != expected {
 		t.Fatalf(`Unexpected LISTEN_ADDR value, got %q instead of %q`, result, expected)
@@ -307,9 +267,14 @@ func TestListenAddrWithPortDefined(t *testing.T) {
 
 func TestDefaultListenAddrValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.ListenAddr()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultListenAddr
+	result := opts.ListenAddr()
 
 	if result != expected {
 		t.Fatalf(`Unexpected LISTEN_ADDR value, got %q instead of %q`, result, expected)
@@ -320,9 +285,13 @@ func TestCertFile(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("CERT_FILE", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.CertFile()
+	result := opts.CertFile()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_FILE value, got %q instead of %q`, result, expected)
@@ -331,9 +300,14 @@ func TestCertFile(t *testing.T) {
 
 func TestDefaultCertFileValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.CertFile()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultCertFile
+	result := opts.CertFile()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_FILE value, got %q instead of %q`, result, expected)
@@ -344,9 +318,13 @@ func TestKeyFile(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("KEY_FILE", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.KeyFile()
+	result := opts.CertKeyFile()
 
 	if result != expected {
 		t.Fatalf(`Unexpected KEY_FILE value, got %q instead of %q`, result, expected)
@@ -355,9 +333,14 @@ func TestKeyFile(t *testing.T) {
 
 func TestDefaultKeyFileValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.KeyFile()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultKeyFile
+	result := opts.CertKeyFile()
 
 	if result != expected {
 		t.Fatalf(`Unexpected KEY_FILE value, got %q instead of %q`, result, expected)
@@ -368,9 +351,13 @@ func TestCertDomain(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("CERT_DOMAIN", "example.org")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "example.org"
-	result := cfg.CertDomain()
+	result := opts.CertDomain()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_DOMAIN value, got %q instead of %q`, result, expected)
@@ -379,9 +366,14 @@ func TestCertDomain(t *testing.T) {
 
 func TestDefaultCertDomainValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.CertDomain()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultCertDomain
+	result := opts.CertDomain()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_DOMAIN value, got %q instead of %q`, result, expected)
@@ -392,9 +384,13 @@ func TestCertCache(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("CERT_CACHE", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.CertCache()
+	result := opts.CertCache()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_CACHE value, got %q instead of %q`, result, expected)
@@ -403,9 +399,14 @@ func TestCertCache(t *testing.T) {
 
 func TestDefaultCertCacheValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.CertCache()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultCertCache
+	result := opts.CertCache()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CERT_CACHE value, got %q instead of %q`, result, expected)
@@ -415,9 +416,13 @@ func TestDefaultCertCacheValue(t *testing.T) {
 func TestDefaultCleanupFrequencyValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultCleanupFrequency
-	result := cfg.CleanupFrequency()
+	result := opts.CleanupFrequency()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CLEANUP_FREQUENCY value, got %v instead of %v`, result, expected)
@@ -428,9 +433,13 @@ func TestCleanupFrequency(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("CLEANUP_FREQUENCY", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.CleanupFrequency()
+	result := opts.CleanupFrequency()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CLEANUP_FREQUENCY value, got %v instead of %v`, result, expected)
@@ -440,9 +449,13 @@ func TestCleanupFrequency(t *testing.T) {
 func TestDefaultWorkerPoolSizeValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultWorkerPoolSize
-	result := cfg.WorkerPoolSize()
+	result := opts.WorkerPoolSize()
 
 	if result != expected {
 		t.Fatalf(`Unexpected WORKER_POOL_SIZE value, got %v instead of %v`, result, expected)
@@ -453,9 +466,13 @@ func TestWorkerPoolSize(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("WORKER_POOL_SIZE", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.WorkerPoolSize()
+	result := opts.WorkerPoolSize()
 
 	if result != expected {
 		t.Fatalf(`Unexpected WORKER_POOL_SIZE value, got %v instead of %v`, result, expected)
@@ -465,9 +482,13 @@ func TestWorkerPoolSize(t *testing.T) {
 func TestDefautPollingFrequencyValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultPollingFrequency
-	result := cfg.PollingFrequency()
+	result := opts.PollingFrequency()
 
 	if result != expected {
 		t.Fatalf(`Unexpected POLLING_FREQUENCY value, got %v instead of %v`, result, expected)
@@ -478,9 +499,13 @@ func TestPollingFrequency(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("POLLING_FREQUENCY", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.PollingFrequency()
+	result := opts.PollingFrequency()
 
 	if result != expected {
 		t.Fatalf(`Unexpected POLLING_FREQUENCY value, got %v instead of %v`, result, expected)
@@ -490,9 +515,13 @@ func TestPollingFrequency(t *testing.T) {
 func TestDefaultBatchSizeValue(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultBatchSize
-	result := cfg.BatchSize()
+	result := opts.BatchSize()
 
 	if result != expected {
 		t.Fatalf(`Unexpected BATCH_SIZE value, got %v instead of %v`, result, expected)
@@ -503,9 +532,13 @@ func TestBatchSize(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("BATCH_SIZE", "42")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 42
-	result := cfg.BatchSize()
+	result := opts.BatchSize()
 
 	if result != expected {
 		t.Fatalf(`Unexpected BATCH_SIZE value, got %v instead of %v`, result, expected)
@@ -515,9 +548,13 @@ func TestBatchSize(t *testing.T) {
 func TestOAuth2UserCreationWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.IsOAuth2UserCreationAllowed()
+	result := opts.IsOAuth2UserCreationAllowed()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_USER_CREATION value, got %v instead of %v`, result, expected)
@@ -528,9 +565,13 @@ func TestOAuth2UserCreationAdmin(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OAUTH2_USER_CREATION", "1")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.IsOAuth2UserCreationAllowed()
+	result := opts.IsOAuth2UserCreationAllowed()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_USER_CREATION value, got %v instead of %v`, result, expected)
@@ -541,9 +582,13 @@ func TestOAuth2ClientID(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OAUTH2_CLIENT_ID", "foobar")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "foobar"
-	result := cfg.OAuth2ClientID()
+	result := opts.OAuth2ClientID()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_CLIENT_ID value, got %q instead of %q`, result, expected)
@@ -552,9 +597,14 @@ func TestOAuth2ClientID(t *testing.T) {
 
 func TestDefaultOAuth2ClientIDValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.OAuth2ClientID()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultOAuth2ClientID
+	result := opts.OAuth2ClientID()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_CLIENT_ID value, got %q instead of %q`, result, expected)
@@ -565,9 +615,13 @@ func TestOAuth2ClientSecret(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OAUTH2_CLIENT_SECRET", "secret")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "secret"
-	result := cfg.OAuth2ClientSecret()
+	result := opts.OAuth2ClientSecret()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_CLIENT_SECRET value, got %q instead of %q`, result, expected)
@@ -576,9 +630,14 @@ func TestOAuth2ClientSecret(t *testing.T) {
 
 func TestDefaultOAuth2ClientSecretValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.OAuth2ClientSecret()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultOAuth2ClientSecret
+	result := opts.OAuth2ClientSecret()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_CLIENT_SECRET value, got %q instead of %q`, result, expected)
@@ -589,9 +648,13 @@ func TestOAuth2RedirectURL(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OAUTH2_REDIRECT_URL", "http://example.org")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "http://example.org"
-	result := cfg.OAuth2RedirectURL()
+	result := opts.OAuth2RedirectURL()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_REDIRECT_URL value, got %q instead of %q`, result, expected)
@@ -600,9 +663,14 @@ func TestOAuth2RedirectURL(t *testing.T) {
 
 func TestDefaultOAuth2RedirectURLValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.OAuth2RedirectURL()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultOAuth2RedirectURL
+	result := opts.OAuth2RedirectURL()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_REDIRECT_URL value, got %q instead of %q`, result, expected)
@@ -613,9 +681,13 @@ func TestOAuth2Provider(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("OAUTH2_PROVIDER", "google")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "google"
-	result := cfg.OAuth2Provider()
+	result := opts.OAuth2Provider()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_PROVIDER value, got %q instead of %q`, result, expected)
@@ -624,9 +696,14 @@ func TestOAuth2Provider(t *testing.T) {
 
 func TestDefaultOAuth2ProviderValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.OAuth2Provider()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultOAuth2Provider
+	result := opts.OAuth2Provider()
 
 	if result != expected {
 		t.Fatalf(`Unexpected OAUTH2_PROVIDER value, got %q instead of %q`, result, expected)
@@ -636,9 +713,13 @@ func TestDefaultOAuth2ProviderValue(t *testing.T) {
 func TestHSTSWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.HasHSTS()
+	result := opts.HasHSTS()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_HSTS value, got %v instead of %v`, result, expected)
@@ -649,9 +730,13 @@ func TestHSTS(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DISABLE_HSTS", "1")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.HasHSTS()
+	result := opts.HasHSTS()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_HSTS value, got %v instead of %v`, result, expected)
@@ -661,9 +746,13 @@ func TestHSTS(t *testing.T) {
 func TestDisableHTTPServiceWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.HasHTTPService()
+	result := opts.HasHTTPService()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_HTTP_SERVICE value, got %v instead of %v`, result, expected)
@@ -674,9 +763,13 @@ func TestDisableHTTPService(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DISABLE_HTTP_SERVICE", "1")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.HasHTTPService()
+	result := opts.HasHTTPService()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_HTTP_SERVICE value, got %v instead of %v`, result, expected)
@@ -686,9 +779,13 @@ func TestDisableHTTPService(t *testing.T) {
 func TestDisableSchedulerServiceWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.HasSchedulerService()
+	result := opts.HasSchedulerService()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_SCHEDULER_SERVICE value, got %v instead of %v`, result, expected)
@@ -699,9 +796,13 @@ func TestDisableSchedulerService(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("DISABLE_SCHEDULER_SERVICE", "1")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.HasSchedulerService()
+	result := opts.HasSchedulerService()
 
 	if result != expected {
 		t.Fatalf(`Unexpected DISABLE_SCHEDULER_SERVICE value, got %v instead of %v`, result, expected)
@@ -712,9 +813,13 @@ func TestArchiveReadDays(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("ARCHIVE_READ_DAYS", "7")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := 7
-	result := cfg.ArchiveReadDays()
+	result := opts.ArchiveReadDays()
 
 	if result != expected {
 		t.Fatalf(`Unexpected ARCHIVE_READ_DAYS value, got %v instead of %v`, result, expected)
@@ -724,9 +829,13 @@ func TestArchiveReadDays(t *testing.T) {
 func TestRunMigrationsWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.RunMigrations()
+	result := opts.RunMigrations()
 
 	if result != expected {
 		t.Fatalf(`Unexpected RUN_MIGRATIONS value, got %v instead of %v`, result, expected)
@@ -737,9 +846,13 @@ func TestRunMigrations(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("RUN_MIGRATIONS", "yes")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.RunMigrations()
+	result := opts.RunMigrations()
 
 	if result != expected {
 		t.Fatalf(`Unexpected RUN_MIGRATIONS value, got %v instead of %v`, result, expected)
@@ -749,9 +862,13 @@ func TestRunMigrations(t *testing.T) {
 func TestCreateAdminWhenUnset(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := false
-	result := cfg.CreateAdmin()
+	result := opts.CreateAdmin()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CREATE_ADMIN value, got %v instead of %v`, result, expected)
@@ -762,9 +879,13 @@ func TestCreateAdmin(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("CREATE_ADMIN", "true")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := true
-	result := cfg.CreateAdmin()
+	result := opts.CreateAdmin()
 
 	if result != expected {
 		t.Fatalf(`Unexpected CREATE_ADMIN value, got %v instead of %v`, result, expected)
@@ -775,9 +896,13 @@ func TestPocketConsumerKeyFromEnvVariable(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("POCKET_CONSUMER_KEY", "something")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "something"
-	result := cfg.PocketConsumerKey("default")
+	result := opts.PocketConsumerKey("default")
 
 	if result != expected {
 		t.Fatalf(`Unexpected POCKET_CONSUMER_KEY value, got %q instead of %q`, result, expected)
@@ -787,9 +912,13 @@ func TestPocketConsumerKeyFromEnvVariable(t *testing.T) {
 func TestPocketConsumerKeyFromUserPrefs(t *testing.T) {
 	os.Clearenv()
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "default"
-	result := cfg.PocketConsumerKey("default")
+	result := opts.PocketConsumerKey("default")
 
 	if result != expected {
 		t.Fatalf(`Unexpected POCKET_CONSUMER_KEY value, got %q instead of %q`, result, expected)
@@ -800,9 +929,13 @@ func TestProxyImages(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("PROXY_IMAGES", "all")
 
-	cfg := NewConfig()
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := "all"
-	result := cfg.ProxyImages()
+	result := opts.ProxyImages()
 
 	if result != expected {
 		t.Fatalf(`Unexpected PROXY_IMAGES value, got %q instead of %q`, result, expected)
@@ -811,9 +944,14 @@ func TestProxyImages(t *testing.T) {
 
 func TestDefaultProxyImagesValue(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
-	result := cfg.ProxyImages()
+
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
 	expected := defaultProxyImages
+	result := opts.ProxyImages()
 
 	if result != expected {
 		t.Fatalf(`Unexpected PROXY_IMAGES value, got %q instead of %q`, result, expected)
@@ -822,19 +960,27 @@ func TestDefaultProxyImagesValue(t *testing.T) {
 
 func TestHTTPSOff(t *testing.T) {
 	os.Clearenv()
-	cfg := NewConfig()
 
-	if cfg.IsHTTPS {
-		t.Fatalf(`Unexpected HTTPS value, got "%v"`, cfg.IsHTTPS)
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
+	if opts.HTTPS {
+		t.Fatalf(`Unexpected HTTPS value, got "%v"`, opts.HTTPS)
 	}
 }
 
 func TestHTTPSOn(t *testing.T) {
 	os.Clearenv()
 	os.Setenv("HTTPS", "on")
-	cfg := NewConfig()
 
-	if !cfg.IsHTTPS {
-		t.Fatalf(`Unexpected HTTPS value, got "%v"`, cfg.IsHTTPS)
+	opts, err := parse()
+	if err != nil {
+		t.Fatalf(`Parsing failure: %q`, err)
+	}
+
+	if !opts.HTTPS {
+		t.Fatalf(`Unexpected HTTPS value, got "%v"`, opts.HTTPS)
 	}
 }
diff --git a/config/doc.go b/config/doc.go
index 4b4814b..c8121ac 100644
--- a/config/doc.go
+++ b/config/doc.go
@@ -1,10 +1,10 @@
-// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Copyright 2019 Frédéric Guillot. All rights reserved.
 // Use of this source code is governed by the Apache 2.0
 // license that can be found in the LICENSE file.
 
 /*
 
-Package config handles configuration values for the application.
+Package config handles configuration management for the application.
 
 */
 package config // import "miniflux.app/config"
diff --git a/config/options.go b/config/options.go
new file mode 100644
index 0000000..ad8d2c7
--- /dev/null
+++ b/config/options.go
@@ -0,0 +1,214 @@
+// Copyright 2019 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package config // import "miniflux.app/config"
+
+const (
+	defaultBaseURL            = "http://localhost"
+	defaultWorkerPoolSize     = 5
+	defaultPollingFrequency   = 60
+	defaultBatchSize          = 10
+	defaultDatabaseURL        = "user=postgres password=postgres dbname=miniflux2 sslmode=disable"
+	defaultDatabaseMaxConns   = 20
+	defaultDatabaseMinConns   = 1
+	defaultArchiveReadDays    = 60
+	defaultListenAddr         = "127.0.0.1:8080"
+	defaultCertFile           = ""
+	defaultKeyFile            = ""
+	defaultCertDomain         = ""
+	defaultCertCache          = "/tmp/cert_cache"
+	defaultCleanupFrequency   = 24
+	defaultProxyImages        = "http-only"
+	defaultOAuth2ClientID     = ""
+	defaultOAuth2ClientSecret = ""
+	defaultOAuth2RedirectURL  = ""
+	defaultOAuth2Provider     = ""
+)
+
+// Options contains configuration options.
+type Options struct {
+	HTTPS                     bool
+	hsts                      bool
+	httpService               bool
+	schedulerService          bool
+	debug                     bool
+	baseURL                   string
+	rootURL                   string
+	basePath                  string
+	databaseURL               string
+	databaseMaxConns          int
+	databaseMinConns          int
+	runMigrations             bool
+	listenAddr                string
+	certFile                  string
+	certDomain                string
+	certCache                 string
+	certKeyFile               string
+	cleanupFrequency          int
+	archiveReadDays           int
+	pollingFrequency          int
+	batchSize                 int
+	workerPoolSize            int
+	createAdmin               bool
+	proxyImages               string
+	oauth2UserCreationAllowed bool
+	oauth2ClientID            string
+	oauth2ClientSecret        string
+	oauth2RedirectURL         string
+	oauth2Provider            string
+	pocketConsumerKey         string
+}
+
+// HasDebugMode returns true if debug mode is enabled.
+func (o *Options) HasDebugMode() bool {
+	return o.debug
+}
+
+// BaseURL returns the application base URL with path.
+func (o *Options) BaseURL() string {
+	return o.baseURL
+}
+
+// RootURL returns the base URL without path.
+func (o *Options) RootURL() string {
+	return o.rootURL
+}
+
+// BasePath returns the application base path according to the base URL.
+func (o *Options) BasePath() string {
+	return o.basePath
+}
+
+// IsDefaultDatabaseURL returns true if the default database URL is used.
+func (o *Options) IsDefaultDatabaseURL() bool {
+	return o.databaseURL == defaultDatabaseURL
+}
+
+// DatabaseURL returns the database URL.
+func (o *Options) DatabaseURL() string {
+	return o.databaseURL
+}
+
+// DatabaseMaxConns returns the maximum number of database connections.
+func (o *Options) DatabaseMaxConns() int {
+	return o.databaseMaxConns
+}
+
+// DatabaseMinConns returns the minimum number of database connections.
+func (o *Options) DatabaseMinConns() int {
+	return o.databaseMinConns
+}
+
+// ListenAddr returns the listen address for the HTTP server.
+func (o *Options) ListenAddr() string {
+	return o.listenAddr
+}
+
+// CertFile returns the SSL certificate filename if any.
+func (o *Options) CertFile() string {
+	return o.certFile
+}
+
+// CertKeyFile returns the private key filename for custom SSL certificate.
+func (o *Options) CertKeyFile() string {
+	return o.certKeyFile
+}
+
+// CertDomain returns the domain to use for Let's Encrypt certificate.
+func (o *Options) CertDomain() string {
+	return o.certDomain
+}
+
+// CertCache returns the directory to use for Let's Encrypt session cache.
+func (o *Options) CertCache() string {
+	return o.certCache
+}
+
+// CleanupFrequency returns the interval for cleanup jobs.
+func (o *Options) CleanupFrequency() int {
+	return o.cleanupFrequency
+}
+
+// WorkerPoolSize returns the number of background worker.
+func (o *Options) WorkerPoolSize() int {
+	return o.workerPoolSize
+}
+
+// PollingFrequency returns the interval to refresh feeds in the background.
+func (o *Options) PollingFrequency() int {
+	return o.pollingFrequency
+}
+
+// BatchSize returns the number of feeds to send for background processing.
+func (o *Options) BatchSize() int {
+	return o.batchSize
+}
+
+// IsOAuth2UserCreationAllowed returns true if user creation is allowed for OAuth2 users.
+func (o *Options) IsOAuth2UserCreationAllowed() bool {
+	return o.oauth2UserCreationAllowed
+}
+
+// OAuth2ClientID returns the OAuth2 Client ID.
+func (o *Options) OAuth2ClientID() string {
+	return o.oauth2ClientID
+}
+
+// OAuth2ClientSecret returns the OAuth2 client secret.
+func (o *Options) OAuth2ClientSecret() string {
+	return o.oauth2ClientSecret
+}
+
+// OAuth2RedirectURL returns the OAuth2 redirect URL.
+func (o *Options) OAuth2RedirectURL() string {
+	return o.oauth2RedirectURL
+}
+
+// OAuth2Provider returns the name of the OAuth2 provider configured.
+func (o *Options) OAuth2Provider() string {
+	return o.oauth2Provider
+}
+
+// HasHSTS returns true if HTTP Strict Transport Security is enabled.
+func (o *Options) HasHSTS() bool {
+	return o.hsts
+}
+
+// RunMigrations returns true if the environment variable RUN_MIGRATIONS is not empty.
+func (o *Options) RunMigrations() bool {
+	return o.runMigrations
+}
+
+// CreateAdmin returns true if the environment variable CREATE_ADMIN is not empty.
+func (o *Options) CreateAdmin() bool {
+	return o.createAdmin
+}
+
+// ProxyImages returns "none" to never proxy, "http-only" to proxy non-HTTPS, "all" to always proxy.
+func (o *Options) ProxyImages() string {
+	return o.proxyImages
+}
+
+// HasHTTPService returns true if the HTTP service is enabled.
+func (o *Options) HasHTTPService() bool {
+	return o.httpService
+}
+
+// HasSchedulerService returns true if the scheduler service is enabled.
+func (o *Options) HasSchedulerService() bool {
+	return o.schedulerService
+}
+
+// ArchiveReadDays returns the number of days after which marking read items as removed.
+func (o *Options) ArchiveReadDays() int {
+	return o.archiveReadDays
+}
+
+// PocketConsumerKey returns the Pocket Consumer Key if configured.
+func (o *Options) PocketConsumerKey(defaultValue string) string {
+	if o.pocketConsumerKey != "" {
+		return o.pocketConsumerKey
+	}
+	return defaultValue
+}
diff --git a/config/parser.go b/config/parser.go
new file mode 100644
index 0000000..996d0a8
--- /dev/null
+++ b/config/parser.go
@@ -0,0 +1,124 @@
+// Copyright 2019 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package config // import "miniflux.app/config"
+
+import (
+	"errors"
+	"fmt"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func parse() (opts *Options, err error) {
+	opts = &Options{}
+	opts.baseURL, opts.rootURL, opts.basePath, err = parseBaseURL()
+	if err != nil {
+		return nil, err
+	}
+
+	opts.debug = getBooleanValue("DEBUG")
+	opts.listenAddr = parseListenAddr()
+
+	opts.databaseURL = getStringValue("DATABASE_URL", defaultDatabaseURL)
+	opts.databaseMaxConns = getIntValue("DATABASE_MAX_CONNS", defaultDatabaseMaxConns)
+	opts.databaseMinConns = getIntValue("DATABASE_MIN_CONNS", defaultDatabaseMinConns)
+	opts.runMigrations = getBooleanValue("RUN_MIGRATIONS")
+
+	opts.hsts = !getBooleanValue("DISABLE_HSTS")
+	opts.HTTPS = getBooleanValue("HTTPS")
+
+	opts.schedulerService = !getBooleanValue("DISABLE_SCHEDULER_SERVICE")
+	opts.httpService = !getBooleanValue("DISABLE_HTTP_SERVICE")
+
+	opts.certFile = getStringValue("CERT_FILE", defaultCertFile)
+	opts.certKeyFile = getStringValue("KEY_FILE", defaultKeyFile)
+	opts.certDomain = getStringValue("CERT_DOMAIN", defaultCertDomain)
+	opts.certCache = getStringValue("CERT_CACHE", defaultCertCache)
+
+	opts.cleanupFrequency = getIntValue("CLEANUP_FREQUENCY", defaultCleanupFrequency)
+	opts.workerPoolSize = getIntValue("WORKER_POOL_SIZE", defaultWorkerPoolSize)
+	opts.pollingFrequency = getIntValue("POLLING_FREQUENCY", defaultPollingFrequency)
+	opts.batchSize = getIntValue("BATCH_SIZE", defaultBatchSize)
+	opts.archiveReadDays = getIntValue("ARCHIVE_READ_DAYS", defaultArchiveReadDays)
+	opts.proxyImages = getStringValue("PROXY_IMAGES", defaultProxyImages)
+
+	opts.oauth2UserCreationAllowed = getBooleanValue("OAUTH2_USER_CREATION")
+	opts.oauth2ClientID = getStringValue("OAUTH2_CLIENT_ID", defaultOAuth2ClientID)
+	opts.oauth2ClientSecret = getStringValue("OAUTH2_CLIENT_SECRET", defaultOAuth2ClientSecret)
+	opts.oauth2RedirectURL = getStringValue("OAUTH2_REDIRECT_URL", defaultOAuth2RedirectURL)
+	opts.oauth2Provider = getStringValue("OAUTH2_PROVIDER", defaultOAuth2Provider)
+
+	opts.pocketConsumerKey = getStringValue("POCKET_CONSUMER_KEY", "")
+
+	opts.createAdmin = getBooleanValue("CREATE_ADMIN")
+
+	return opts, nil
+}
+
+func parseBaseURL() (string, string, string, error) {
+	baseURL := os.Getenv("BASE_URL")
+	if baseURL == "" {
+		return defaultBaseURL, defaultBaseURL, "", nil
+	}
+
+	if baseURL[len(baseURL)-1:] == "/" {
+		baseURL = baseURL[:len(baseURL)-1]
+	}
+
+	u, err := url.Parse(baseURL)
+	if err != nil {
+		return "", "", "", fmt.Errorf("Invalid BASE_URL: %v", err)
+	}
+
+	scheme := strings.ToLower(u.Scheme)
+	if scheme != "https" && scheme != "http" {
+		return "", "", "", errors.New("Invalid BASE_URL: scheme must be http or https")
+	}
+
+	basePath := u.Path
+	u.Path = ""
+	return baseURL, u.String(), basePath, nil
+}
+
+func parseListenAddr() string {
+	if port := os.Getenv("PORT"); port != "" {
+		return ":" + port
+	}
+
+	return getStringValue("LISTEN_ADDR", defaultListenAddr)
+}
+
+func getBooleanValue(key string) bool {
+	value := strings.ToLower(os.Getenv(key))
+	if value == "1" || value == "yes" || value == "true" || value == "on" {
+		return true
+	}
+	return false
+}
+
+func getStringValue(key, fallback string) string {
+	value := os.Getenv(key)
+	if value == "" {
+		return fallback
+	}
+
+	return value
+}
+
+func getIntValue(key string, fallback int) int {
+	value := os.Getenv(key)
+	if value == "" {
+		return fallback
+	}
+
+	v, err := strconv.Atoi(value)
+	if err != nil {
+		return fallback
+	}
+
+	return v
+}
diff --git a/config/parser_test.go b/config/parser_test.go
new file mode 100644
index 0000000..ba454b4
--- /dev/null
+++ b/config/parser_test.go
@@ -0,0 +1,79 @@
+// Copyright 2019 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package config // import "miniflux.app/config"
+
+import (
+	"os"
+	"testing"
+)
+
+func TestGetBooleanValueWithUnsetVariable(t *testing.T) {
+	os.Clearenv()
+	if getBooleanValue("MY_TEST_VARIABLE") {
+		t.Errorf(`Unset variables should returns false`)
+	}
+}
+
+func TestGetBooleanValue(t *testing.T) {
+	scenarios := map[string]bool{
+		"":        false,
+		"1":       true,
+		"Yes":     true,
+		"yes":     true,
+		"True":    true,
+		"true":    true,
+		"on":      true,
+		"false":   false,
+		"off":     false,
+		"invalid": false,
+	}
+
+	for input, expected := range scenarios {
+		os.Clearenv()
+		os.Setenv("MY_TEST_VARIABLE", input)
+		result := getBooleanValue("MY_TEST_VARIABLE")
+		if result != expected {
+			t.Errorf(`Unexpected result for %q, got %v instead of %v`, input, result, expected)
+		}
+	}
+}
+
+func TestGetStringValueWithUnsetVariable(t *testing.T) {
+	os.Clearenv()
+	if getStringValue("MY_TEST_VARIABLE", "defaultValue") != "defaultValue" {
+		t.Errorf(`Unset variables should returns the default value`)
+	}
+}
+
+func TestGetStringValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("MY_TEST_VARIABLE", "test")
+	if getStringValue("MY_TEST_VARIABLE", "defaultValue") != "test" {
+		t.Errorf(`Defined variables should returns the specified value`)
+	}
+}
+
+func TestGetIntValueWithUnsetVariable(t *testing.T) {
+	os.Clearenv()
+	if getIntValue("MY_TEST_VARIABLE", 42) != 42 {
+		t.Errorf(`Unset variables should returns the default value`)
+	}
+}
+
+func TestGetIntValueWithInvalidInput(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("MY_TEST_VARIABLE", "invalid integer")
+	if getIntValue("MY_TEST_VARIABLE", 42) != 42 {
+		t.Errorf(`Invalid integer should returns the default value`)
+	}
+}
+
+func TestGetIntValue(t *testing.T) {
+	os.Clearenv()
+	os.Setenv("MY_TEST_VARIABLE", "2018")
+	if getIntValue("MY_TEST_VARIABLE", 42) != 2018 {
+		t.Errorf(`Defined variables should returns the specified value`)
+	}
+}