Added remote.<name>.annex-push and remote.<name>.annex-pull

The former can be useful to make remotes that don't get fully synced with
local changes, which comes up in a lot of situations.

The latter was mostly added for symmetry, but could be useful (though less
likely to be).

Implementing `remote.<name>.annex-pull` was a bit tricky, as there's no one
place where git-annex pulls/fetches from remotes. I audited all
instances of "fetch" and "pull". A few cases were left not checking this
config:

* Git.Repair can try to pull missing refs from a remote, and if the local
  repo is corrupted, that seems a reasonable thing to do even though
  the config would normally prevent it.
* Assistant.WebApp.Gpg and Remote.Gcrypt and Remote.Git do fetches
  as part of the setup process of a remote. The config would probably not
  be set then, and having the setup fail seems worse than honoring it if it
  is already set.

I have not prevented all the code that does a "merge" from merging branches
from remotes with remote.<name>.annex-pull=false. That could perhaps
be done, but it would need a way to map from branch name to remote name,
and the way refspecs work makes that hard to get really correct. So if the
user fetches manually, the git-annex branch will get merged, for example.
Anther way of looking at/justifying this is that the setting is called
"annex-pull", not "annex-merge".

This commit was supported by the NSF-funded DataLad project.

4 files changed, 54 insertions, 8 deletions

diff --git a/doc/git-annex-remotedaemon.mdwn b/doc/git-annex-remotedaemon.mdwn
index b01002dc9..609698e97 100644
--- a/doc/git-annex-remotedaemon.mdwn
+++ b/doc/git-annex-remotedaemon.mdwn
@@ -29,6 +29,9 @@ accepting connections from other nodes and serving up the contents of the
 repository. This is only done if you first run `git annex enable-tor`.
 Use `git annex p2p` to configure access to tor-annex remotes.
 
+Note that when `remote.<name>.annex-pull` is set to false, the remotedaemon
+will avoid fetching changes from that remote.
+
 # OPTIONS
 
 * `--foreground`
diff --git a/doc/git-annex-sync.mdwn b/doc/git-annex-sync.mdwn
index 97c63d340..cabe5fed9 100644
--- a/doc/git-annex-sync.mdwn
+++ b/doc/git-annex-sync.mdwn
@@ -8,10 +8,7 @@ git annex sync `[remote ...]`
 
 # DESCRIPTION
 
-Use this command when you want to synchronize the local repository with
-one or more of its remotes. You can specify the remotes (or remote
-groups) to sync with by name; the default if none are specified is to
-sync with all remotes.
+This command synchronizes the local repository with its remotes.
 
 The sync process involves first committing any local changes to files
 that have previously been added to the repository,
@@ -36,6 +33,12 @@ by running "git annex sync" on the remote.
 
 # OPTIONS
 
+* `[remote]`
+
+  By default, all remotes are synced, except for remotes that have
+  `remote.<name>.annex-sync` set to false. By specifying the names
+  of remotes (or remote groups), you can control which ones to sync with.
+
 * `--fast`
 
   Only sync with the remotes with the lowest annex-cost value configured.
@@ -52,11 +55,21 @@ by running "git annex sync" on the remote.
 
 * `--pull`, `--no-pull`
 
-  By default, git pulls from remotes. Use --no-pull to disable.
+  By default, git pulls from remotes. Use --no-pull to disable all pulling.
+
+  When `remote.<name>.annex-pull` or `remote.<name>.annex-sync`
+  are set to false, pulling is disabled for those remotes, and using
+  `--pull` will not enable it.
 
 * `--push`, `--no-push` 
 
-  By default, git pushes to remotes. Use --no-push to disable.
+  By default, git pushes changes to remotes.
+  Use --no-push to disable all pushing.
+  
+  When `remote.<name>.annex-push` or `remote.<name>.annex-sync` are
+  set to false, or `remote.<name>.annex-readonly` is set to true,
+  pushing is disabled for those remotes, and using `--push` will not enable
+  it.
 
 * `--content`, `--no-content`
 
@@ -64,7 +77,7 @@ by running "git annex sync" on the remote.
   The --content option causes the content of files in the work tree
   to also be uploaded and downloaded as necessary.
 
-  The annex.synccontent configuration can be set to true to make content
+  The `annex.synccontent` configuration can be set to true to make content
   be synced by default.
 
   Normally this tries to get each annexed file in the work tree
diff --git a/doc/git-annex.mdwn b/doc/git-annex.mdwn
index 07b8b19e1..2bebd9f49 100644
--- a/doc/git-annex.mdwn
+++ b/doc/git-annex.mdwn
@@ -1156,7 +1156,18 @@ Here are all the supported configuration settings.
 * `remote.<name>.annex-sync`
 
   If set to `false`, prevents git-annex sync (and the git-annex assistant)
-  from syncing with this remote.
+  from syncing with this remote by default. However, `git annex sync <name>`
+  can still be used to sync with the remote.
+
+* `remote.<name>.annex-pull`
+
+  If set to `false`, prevents git-annex sync (and the git-annex assistant
+  etc) from ever pulling (or fetching) from the remote.
+
+* `remote.<name>.annex-push`
+
+  If set to `false`, prevents git-annex sync (and the git-annex assistant
+  etc) from ever pushing to the remote.
 
 * `remote.<name>.annex-readonly`
 
diff --git a/doc/tips/semi-synchronized_remotes/comment_1_d0459d72b7e0441fe833a5c8e1588a4f._comment b/doc/tips/semi-synchronized_remotes/comment_1_d0459d72b7e0441fe833a5c8e1588a4f._comment
new file mode 100644
index 000000000..0a6aeb9d6
--- /dev/null
+++ b/doc/tips/semi-synchronized_remotes/comment_1_d0459d72b7e0441fe833a5c8e1588a4f._comment
@@ -0,0 +1,19 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2017-04-05T16:11:57Z"
+ content="""
+Setting `remote.<name>.annex-readonly=true` prevents git-annex sync
+from pushing changes to the remote. It also prevents any git-annex command
+from copying annexed file contents to the remote, or deleting annexed file
+contents. So I think it's ideal for this kind of situation.
+
+There does seem to be room for configs to prevent sync from pulling/pushing
+without making the remote fully readonly. For example, the remote might be
+a source of content, that only knows about the files it added and not other
+files in the local repository, so dropping files from it should be allowed
+but not pushing to it.
+
+So, I've added `remote.<name>.annex-push` and
+`remote.<name>.annex-pull`.
+"""]]