Make it possible to easily deploy serverless functions

This commits add a job that is going to be triggered whenever someone
adds `[serverless deploy-functions]` text into their commit message.

This make it really simple to deploy functions in FaaS-only project.

lib/gitlab/ci/templates/Serverless.gitlab-ci.yml

@@ -6,7 +6,7 @@ stages:
   - build
   - deploy
 
-.serverless:build:dockerfile:
+.serverless:build:image:
   variables:
     DOCKERFILE: "Dockerfile"
   stage: build
@@ -14,6 +14,7 @@ stages:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
   only:
+    refs:
       - master
   script:
     - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
@@ -23,6 +24,7 @@ stages:
   stage: deploy
   image: gcr.io/triggermesh/tm@sha256:e3ee74db94d215bd297738d93577481f3e4db38013326c90d57f873df7ab41d5
   only:
+    refs:
       - master
   environment: development
   script:
@@ -37,3 +39,10 @@ stages:
    - tm -n "$KUBE_NAMESPACE" set registry-auth gitlab-registry --registry "$CI_REGISTRY" --username "$CI_REGISTRY_USER" --password "$CI_JOB_TOKEN" --push
    - tm -n "$KUBE_NAMESPACE" set registry-auth gitlab-registry --registry "$CI_REGISTRY" --username "$CI_DEPLOY_USER" --password "$CI_DEPLOY_PASSWORD" --pull
    - tm -n "$KUBE_NAMESPACE" deploy --wait
+
+deploy-functions:
+  extends: .serverless:deploy:functions
+  environment: production
+  only:
+    variables:
+      - $CI_COMMIT_MESSAGE =~ /\[serverless deploy-functions\]/