refactor: move branch name fetching to new script

Also properly detect injected branch name.

bin/dokku-deploy

@@ -8,34 +8,12 @@ ssh_remote="ssh://dokku@$(parse-ssh-host):$(parse-ssh-port)"
 
 if [ "$COMMAND" = "review-apps:create" ] || [ "$COMMAND" = 'review-apps:destroy' ]; then
   if [ -z "$REVIEW_APP_NAME" ]; then
-    CI_BRANCH_NAME=""
-    if [ -n "$CI_COMMIT_REF_NAME" ]; then
-      # gitlab-ci
-      CI_BRANCH_NAME="$CI_COMMIT_REF_NAME"
-    elif [ -n "$GITHUB_REF" ]; then
-      # github actions
-      CI_BRANCH_NAME="${GITHUB_REF#refs/heads/}"
-    elif [ -n "$CIRCLE_BRANCH" ]; then
-      # circleci
-      CI_BRANCH_NAME="$CIRCLE_BRANCH"
-    elif [ -n "$TRAVIS_BRANCH" ]; then
-      # travisci
-      CI_BRANCH_NAME="$TRAVIS_BRANCH"
-    elif [ -n "$SEMAPHORE_GIT_BRANCH" ]; then
-      # semaphoreci
-      CI_BRANCH_NAME="SEMAPHORE_GIT_BRANCH"
-    elif [ -n "$CI_BRANCH" ]; then
-      # cloudbees
-      CI_BRANCH_NAME="CI_BRANCH"
-    elif [ -n "$DRONE_COMMIT_BRANCH" ]; then
-      # drone
-      CI_BRANCH_NAME="DRONE_COMMIT_BRANCH"
-    else
+    CI_BRANCH_NAME="$(parse-ci-branch-name)"
+    if [ -z "$CI_BRANCH_NAME" ]; then
       log-error "Unable to detect branch name and cannot generate review app name"
       exit 1
     fi
 
-    CI_BRANCH_NAME="$(echo "$CI_BRANCH_NAME" | tr '[:upper:]' '[:lower:]' | sed "s/[[:alpha:].-]/-/g")"
     REVIEW_APP_NAME="review-${app_name}-${CI_BRANCH_NAME}"
     log-info "No review app name specified, using $REVIEW_APP_NAME"
   fi

bin/parse-ci-branch-name

@@ -0,0 +1,32 @@
+#!/bin/sh -l
+set -e
+
+value="$CI_BRANCH_NAME"
+if [ -n "$CI_BRANCH_NAME" ]; then
+  true
+elif [ -n "$CI_COMMIT_REF_NAME" ]; then
+  # gitlab-ci
+  value="$CI_COMMIT_REF_NAME"
+elif [ -n "$GITHUB_REF" ]; then
+  # github actions
+  value="${GITHUB_REF#refs/heads/}"
+elif [ -n "$CIRCLE_BRANCH" ]; then
+  # circleci
+  value="$CIRCLE_BRANCH"
+elif [ -n "$TRAVIS_BRANCH" ]; then
+  # travisci
+  value="$TRAVIS_BRANCH"
+elif [ -n "$SEMAPHORE_GIT_BRANCH" ]; then
+  # semaphoreci
+  value="SEMAPHORE_GIT_BRANCH"
+elif [ -n "$CI_BRANCH" ]; then
+  # cloudbees
+  value="CI_BRANCH"
+elif [ -n "$DRONE_COMMIT_BRANCH" ]; then
+  # drone
+  value="DRONE_COMMIT_BRANCH"
+else
+  exit 0
+fi
+
+echo "$value" | tr '[:upper:]' '[:lower:]' | sed "s/[[:alpha:].-]/-/g"