set remote's annexUrl automatically

When the remote repository's git config file
has annex.url set to an annex+http url.

Remote/Git.hs

@@ -340,6 +340,12 @@ tryGitConfigRead autoinit r hasuuid
 				-- optimisation.
 				unless (fromMaybe False $ Git.Config.isBare r') $
 					setremote setRemoteBare False
+				-- When annex.url is set to a P2P http url,
+				-- store in remote.name.annexUrl
+				case Git.fromConfigValue <$> Git.Config.getMaybe (annexConfig "url") r' of
+					Just u | isP2PHttpProtocolUrl u ->
+						setremote (setConfig . annexUrlConfigKey) u
+					_ -> noop
 				return r'
 			Left err -> do
 				set_ignore "not usable by git-annex" False

Types/GitConfig.hs

@@ -109,6 +109,7 @@ data GitConfig = GitConfig
 	, annexSyncMigrations :: Bool
 	, annexDebug :: Bool
 	, annexDebugFilter :: Maybe String
+	, annexUrl :: Maybe String
 	, annexWebOptions :: [String]
 	, annexYoutubeDlOptions :: [String]
 	, annexYoutubeDlCommand :: Maybe String
@@ -204,6 +205,7 @@ extractGitConfig configsource r = GitConfig
 	, annexSyncMigrations = getbool (annexConfig "syncmigrations") True
 	, annexDebug = getbool (annexConfig "debug") False
 	, annexDebugFilter = getmaybe (annexConfig "debugfilter")
+	, annexUrl = getmaybe (annexConfig "url")
 	, annexWebOptions = getwords (annexConfig "web-options")
 	, annexYoutubeDlOptions = getwords (annexConfig "youtube-dl-options")
 	, annexYoutubeDlCommand = getmaybe (annexConfig "youtube-dl-command")

doc/git-annex.mdwn

@@ -1242,6 +1242,13 @@ repository, using [[git-annex-config]]. See its man page for a list.)
   After changing this config, you need to re-run `git-annex init` for it
   to take effect.
 
+* `annex.url`
+
+  When a remote has a http url, the first time git-annex uses the remote
+  it will check if it can download its `.git/config` file. If it is able
+  to, and the file has this config set to an "annex+http" or "annex+https"
+  url, that url will be copied into `remote.<name>.annexUrl`. 
+
 * `annex.resolvemerge`
 
   Set to false to prevent merge conflicts in the checked out branch

doc/tips/smart_http_server.mdwn

@@ -15,22 +15,26 @@ You will still need to run a web server to serve the git repository.
 [[API|design/p2p_protocol_over_http]], and it does it
 on a different port (9417 by default).
 
-All you need to do on the server is to arrange to run 
-`git-annex p2phttp` in your repository as a daemon, or service.
-Note that it should not be run as root, but as whatever user owns the
-repository. It has several options you can use to configure it, including
-controlling who can access the repository.
+You will need to arrange to run `git-annex p2phttp` in your repository as a
+daemon or service. Note that it should not be run as root, but as whatever
+user owns the repository. It has several options you can use to configure
+it, including controlling who can access the repository.
 
-After cloning a repository, it's necessary to configure
-`remote.name.annexUrl` to an "annex+http" or "annex+https" url,
-so that git-annex knows where the API endpoint is.
+So there are two web servers, and thus two different urls.
+A remote will have `remote.name.url` set to the http url
+that git will use, and also have `remote.name.annexUrl` set to the url
+that git-annex will use to talk to `git-annex p2phttp`. That url
+looks like this:
+    
+    annex+http://example.com/git-annex/bbdac17e-6633-4b27-8f7b-fb447d5bae7c
 
-For example:
+The "annex+http" (or "annex+https") indicates that it's a git-annex API
+url, which defaults to being on port 9417 unless a different port is set.
+And the last part of the url is the annex.uuid of the repository.
 
-    git clone http://example.com/foo.git
-    cd foo
-    git config remote.origin.annexUrl annex+http://example.com/git-annex/bbdac17e-6633-4b27-8f7b-fb447d5bae7c
-    git-annex get ...
-
-The last part of the "annex+http" url is the annex.uuid of the
-remote repository.
+It would be annoying if every user who cloned your repository 
+had to set `remote.name.annexUrl` manually. So there's a way to automate it.
+In the git config file of the repository, set `annex.url` to the "annex+http"
+(or "annex+https") url. The first time it uses a http remote, git-annex
+downloads the git config file, and sets `remote.name.annexUrl` to the value
+of annex.url.

doc/todo/git-annex_proxies.mdwn

@@ -28,11 +28,6 @@ Planned schedule of work:
 
 ## work notes
 
-* When getting the remote .git/config of a http remote, check if
-  annex.apiurl is set, and if so, set the remote's annexUrl automically.
-
-  git-annex-p2phttp could automatically set annex.apiurl as well.
-
 * An interrupted PUT to cluster that has a node that is a special remote
   over http leaves open the connection to the cluster, so the next request
   opens another one.