1 files changed, 109 insertions, 0 deletions
diff --git a/test/cpp/naming/utils/run_dns_server_for_lb_interop_tests.py b/test/cpp/naming/utils/run_dns_server_for_lb_interop_tests.py
new file mode 100755
index 0000000000..97171e21da
--- /dev/null
+++ b/test/cpp/naming/utils/run_dns_server_for_lb_interop_tests.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python2.7
+# Copyright 2015 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import argparse
+import subprocess
+import os
+import tempfile
+import sys
+import time
+import signal
+import yaml
+
+argp = argparse.ArgumentParser(description='Runs a DNS server for LB interop tests')
+argp.add_argument('-l', '--grpclb_ips', default=None, type=str,
+                  help='Comma-separated list of IP addresses of balancers')
+argp.add_argument('-f', '--fallback_ips', default=None, type=str,
+                  help='Comma-separated list of IP addresses of fallback servers')
+argp.add_argument('-c', '--cause_no_error_no_data_for_balancer_a_record',
+                  default=False, action='store_const', const=True,
+                  help=('Used for testing the case in which the grpclb '
+                        'balancer A record lookup results in a DNS NOERROR response '
+                        'but with no ANSWER section i.e. no addresses'))
+args = argp.parse_args()
+
+balancer_records = []
+grpclb_ips = args.grpclb_ips.split(',')
+if grpclb_ips[0]:
+    for ip in grpclb_ips:
+        balancer_records.append({
+            'TTL': '2100',
+            'data': ip,
+            'type': 'A',
+        })
+fallback_records = []
+fallback_ips = args.fallback_ips.split(',')
+if fallback_ips[0]:
+    for ip in fallback_ips:
+        fallback_records.append({
+            'TTL': '2100',
+            'data': ip,
+            'type': 'A',
+        })
+records_config_yaml = {
+    'resolver_tests_common_zone_name':
+    'test.google.fr.',
+    'resolver_component_tests': [{
+        'records': {
+            '_grpclb._tcp.server': [
+                {
+                    'TTL': '2100',
+                    'data': '0 0 12000 balancer',
+                    'type': 'SRV'
+                },
+            ],
+            'balancer':
+            balancer_records,
+            'server':
+            fallback_records,
+        }
+    }]
+}
+if args.cause_no_error_no_data_for_balancer_a_record:
+    balancer_records = records_config_yaml[
+        'resolver_component_tests'][0]['records']['balancer']
+    assert not balancer_records
+    # Insert a TXT record at the balancer.test.google.fr. domain.
+    # This TXT record won't actually be resolved or used by gRPC clients;
+    # inserting this record is just a way get the balancer.test.google.fr.
+    # A record queries to return NOERROR DNS responses that also have no
+    # ANSWER section, in order to simulate this failure case.
+    balancer_records.append({
+        'TTL': '2100',
+        'data': 'arbitrary string that wont actually be resolved',
+        'type': 'TXT',
+    })
+# Generate the actual DNS server records config file
+records_config_path = tempfile.mktemp()
+with open(records_config_path, 'w') as records_config_generated:
+    records_config_generated.write(yaml.dump(records_config_yaml))
+
+with open(records_config_path, 'r') as records_config_generated:
+    sys.stderr.write('===== DNS server records config: =====\n')
+    sys.stderr.write(records_config_generated.read())
+    sys.stderr.write('======================================\n')
+
+# Run the DNS server
+# Note that we need to add the extra
+# A record for metadata.google.internal in order for compute engine
+# OAuth creds and ALTS creds to work.
+# TODO(apolcyn): should metadata.google.internal always resolve
+# to 169.254.169.254?
+subprocess.check_output([
+    '/var/local/git/grpc/test/cpp/naming/utils/dns_server.py', '--port=53',
+    '--records_config_path', records_config_path,
+    '--add_a_record=metadata.google.internal:169.254.169.254',
+])