Add subtree capability using :repo_tree variable

The variable `:repo_tree` now allows the specification of a sub-tree
that will be extracted from the repository when deploying. This is
useful when deploying a project that lives in a subdirectory of a larger
repository.  Implemented only for git and hg.  If not defined then the
behaviour is as previously and the whole repository is extracted.
All extraction is as before still subject to git-archive `.gitattributes`

CHANGELOG.md

@@ -6,6 +6,14 @@ Reverse Chronological Order:
 
 https://github.com/capistrano/capistrano/compare/v3.2.1...HEAD
 
+* Enhancement (@townsen)
+  * Added the variable `:repo_tree` which allows the specification of a sub-tree that
+    will be extracted from the repository. This is useful when deploying a project
+    that lives in a subdirectory of a larger repository.
+    Implemented only for git and hg.
+    If not defined then the behaviour is as previously and the whole repository is
+    extracted (subject to git-archive `.gitattributes` of course).
+
 * Enhancements (@townsen)
   * Previously filtering would affect any generated configuration files so that
     files newly deployed would not be the same as those on the hosts previously

README.md

@@ -257,6 +257,7 @@ The following variables are settable:
 | Variable Name         | Description                                                          | Notes                                                           |
 |:---------------------:|----------------------------------------------------------------------|-----------------------------------------------------------------|
 | `:repo_url`           | The URL of your scm repository (git, hg, svn)                        | file://, https://, ssh://, or svn+ssh:// are all supported      |
+| `:repo_tree`          | The subtree of the scm repository to deploy (git, hg)                | Only implemented for git and hg repos. Extract just this tree   |
 | `:branch`             | The branch you wish to deploy                                        | This only has meaning for git and hg repos, to specify the branch of an svn repo, set `:repo_url` to the branch location. |
 | `:scm`                | The source control system used                                       | `:git`, `:hg`, `:svn` are currently supported                   |
 | `:tmp_dir`            | The (optional) temp directory that will be used (default: /tmp)      | if you have a shared web host, this setting may need to be set (i.e. /home/user/tmp/capistrano). |

lib/capistrano/git.rb

@@ -30,7 +30,13 @@ class Capistrano::Git < Capistrano::SCM
     end
 
     def release
-      git :archive, fetch(:branch), '| tar -x -f - -C', release_path
+      if tree = fetch(:repo_tree)
+        tree = tree.slice %r#^/?(.*?)/?$#, 1
+        components = tree.split('/').size
+        git :archive, fetch(:branch), tree, "| tar -x --strip-components #{components} -f - -C", release_path
+      else
+        git :archive, fetch(:branch), '| tar -x -f - -C', release_path
+      end
     end
 
     def fetch_revision

lib/capistrano/hg.rb

@@ -27,7 +27,13 @@ class Capistrano::Hg < Capistrano::SCM
     end
 
     def release
-      hg "archive", release_path, "--rev", fetch(:branch)
+      if tree = fetch(:repo_tree)
+        tree = tree.slice %r#^/?(.*?)/?$#, 1
+        components = tree.split('/').size
+        hg "archive --type tgz -p . -I", tree, "--rev", fetch(:branch), "| tar -x --strip-components #{components} -f - -C", release_path
+      else
+        hg "archive", release_path, "--rev", fetch(:branch)
+      end
     end
 
     def fetch_revision

spec/lib/capistrano/git_spec.rb

@@ -57,14 +57,25 @@ module Capistrano
     end
 
     describe "#release" do
-      it "should run git archive" do
-        context.expects(:fetch).returns(:branch)
+      it "should run git archive without a subtree" do
+        context.expects(:fetch).with(:repo_tree).returns(nil)
+        context.expects(:fetch).with(:branch).returns(:branch)
         context.expects(:release_path).returns(:path)
 
         context.expects(:execute).with(:git, :archive, :branch, '| tar -x -f - -C', :path)
 
         subject.release
       end
+
+      it "should run git archive with a subtree" do
+        context.expects(:fetch).with(:repo_tree).returns('tree')
+        context.expects(:fetch).with(:branch).returns(:branch)
+        context.expects(:release_path).returns(:path)
+
+        context.expects(:execute).with(:git, :archive, :branch, 'tree', '| tar -x --strip-components 1 -f - -C', :path)
+
+        subject.release
+      end
     end
   end
 end

spec/lib/capistrano/hg_spec.rb

@@ -57,14 +57,25 @@ module Capistrano
     end
 
     describe "#release" do
-      it "should run hg archive" do
-        context.expects(:fetch).returns(:branch)
+      it "should run hg archive without a subtree" do
+        context.expects(:fetch).with(:repo_tree).returns(nil)
+        context.expects(:fetch).with(:branch).returns(:branch)
         context.expects(:release_path).returns(:path)
 
         context.expects(:execute).with(:hg, "archive", :path, "--rev", :branch)
 
         subject.release
       end
+
+      it "should run hg archive with a subtree" do
+        context.expects(:fetch).with(:repo_tree).returns('tree')
+        context.expects(:fetch).with(:branch).returns(:branch)
+        context.expects(:release_path).returns(:path)
+
+        context.expects(:execute).with(:hg, "archive --type tgz -p . -I", 'tree', "--rev", :branch, '| tar -x --strip-components 1 -f - -C', :path)
+
+        subject.release
+      end
     end
   end
 end