Allow specifying the deploy branch via DOKKU_DEPLOY_BRANCH

Closes #2494

docs/deployment/application-deployment.md

@@ -90,6 +90,18 @@ Dokku supports deploying applications via [Heroku buildpacks](https://devcenter.
 
 Dokku only supports deploying from its master branch, so if you'd like to deploy a different local branch use: ```git push dokku <local branch>:master```
 
+An alternative is to use the `DOKKU_DEPLOY_BRANCH` application config value to specify a branch that should be deployed. The implicit default is master, and this can be modified both at the app and global level:
+
+```shell
+# on your Dokku host
+
+# set it globally
+dokku config:set --global DOKKU_DEPLOY_BRANCH=some-branch
+
+# override for a specific app
+dokku config:set ruby-rails-sample DOKKU_DEPLOY_BRANCH=some-branch
+```
+
 You can also support pushing multiple branches using the [receive-branch](/dokku/development/plugin-triggers/#receive-branch) plugin trigger in a custom plugin.
 
 ### Skipping deployment

plugins/git/functions

@@ -55,16 +55,39 @@ suppress_output() {
   return 0
 }
 
+git_deploy_branch() {
+  declare desc="retrieve the deploy branch for a given application"
+  local cmd="git-hook"
+  local APP="$1"
+
+  local DOKKU_DEPLOY_BRANCH="$(config_get "$APP" DOKKU_DEPLOY_BRANCH || true)"
+  local DOKKU_GLOBAL_DEPLOY_BRANCH="$(config_get --global DOKKU_DEPLOY_BRANCH || true)"
+  if [[ -n "$DOKKU_DEPLOY_BRANCH" ]]; then
+    echo "$DOKKU_DEPLOY_BRANCH"
+  elif [[ -n "$DOKKU_GLOBAL_DEPLOY_BRANCH" ]]; then
+    echo "$DOKKU_GLOBAL_DEPLOY_BRANCH"
+  else
+    echo "master"
+  fi
+}
+
 git_hook_cmd() {
   declare desc="kick off receive-app trigger from git prereceive hook"
   local cmd="git-hook"
   local APP="$2"  
+  local DOKKU_DEPLOY_BRANCH="$(git_deploy_branch "$APP")"
+
+  if ! git check-ref-format --branch "$DOKKU_DEPLOY_BRANCH" 2> /dev/null; then
+    echo $'\e[1G\e[K'"-----> WARNING: Invalid branch name '$DOKKU_DEPLOY_BRANCH' specified via DOKKU_DEPLOY_BRANCH."
+    echo $'\e[1G\e[K'"-----> For more details, please see the man page for 'git-check-ref-format.'"
+    return
+  fi
 
   local oldrev newrev refname
   while read -r oldrev newrev refname; do
     # Only run this script for the master branch. You can remove this
     # if block if you wish to run it for others as well.
-    if [[ $refname = "refs/heads/master" ]]; then
+    if [[ $refname = "refs/heads/${DOKKU_DEPLOY_BRANCH}" ]]; then
       # broken out into plugin so we might support other methods to receive an app
       # shellcheck disable=SC2086
       plugn trigger receive-app $APP $newrev

tests/unit/20_config.bats

@@ -145,3 +145,17 @@ teardown() {
   echo "status: "$status
   assert_success
 }
+
+@test "(config) deploy specific DOKKU_DEPLOY_BRANCH" {
+  run ssh dokku@dokku.me config:set --global DOKKU_DEPLOY_BRANCH=global-branch
+  GIT_REMOTE_BRANCH=global-branch deploy_app
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  run ssh dokku@dokku.me config:set $TEST_APP DOKKU_DEPLOY_BRANCH=app-branch
+  GIT_REMOTE_BRANCH=app-branch deploy_app
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}

tests/unit/test_helper.bash

@@ -196,10 +196,11 @@ assert_http_redirect() {
 }
 
 deploy_app() {
-  local APP_TYPE="$1"; local APP_TYPE=${APP_TYPE:="nodejs-express"}
+  declare APP_TYPE="$1" GIT_REMOTE="$2" CUSTOM_TEMPLATE="$3" CUSTOM_PATH="$4"
-  local GIT_REMOTE="$2"; local GIT_REMOTE=${GIT_REMOTE:="dokku@dokku.me:$TEST_APP"}
+  local APP_TYPE=${APP_TYPE:="nodejs-express"}
-  local CUSTOM_TEMPLATE="$3"; local TMP=$(mktemp -d "/tmp/dokku.me.XXXXX")
+  local GIT_REMOTE=${GIT_REMOTE:="dokku@dokku.me:$TEST_APP"}
-  local CUSTOM_PATH="$4"
+  local GIT_REMOTE_BRANCH=${GIT_REMOTE_BRANCH:="master"}
+  local TMP=$(mktemp -d "/tmp/dokku.me.XXXXX")
 
   rmdir "$TMP" && cp -r "./tests/apps/$APP_TYPE" "$TMP"
 
@@ -218,7 +219,7 @@ deploy_app() {
   [[ -f gitignore ]] && mv gitignore .gitignore
   git add .
   git commit -m 'initial commit'
-  git push target master || destroy_app $?
+  git push target "master:${GIT_REMOTE_BRANCH}" || destroy_app $?
 }
 
 setup_client_repo() {