docker: Add a new image for the gst-indent job

This is meant run GNU indent along with the gstreamer wrapper
through the codebase and error out for missconfigured code.

Part of https://gitlab.freedesktop.org/gstreamer/gstreamer-project/issues/33

.gitlab-ci.yml

@@ -73,6 +73,18 @@ alpine amd64 manifest builder docker:
       - 'docker/build_manifest/*'
       - 'gitlab/build_manifest.py'
 
+gst-indent amd64 docker:
+  stage: "build docker"
+  variables:
+    ARCH: "amd64"
+    TAG: "gst-indent"
+    CONTEXT_DIR: "docker/indent/"
+    DOCKERFILE: "docker/indent/Dockerfile"
+  extends: .base
+  only:
+    changes:
+      - 'docker/indent/*'
+
 fedora amd64 docker:
   stage: "build docker"
   variables:

docker/indent/Dockerfile

@@ -0,0 +1,5 @@
+FROM debian:stretch-slim
+
+RUN apt update -yqq \
+    && apt install -y curl indent git findutils \
+    && rm -R /var/lib/apt/ /var/log/apt/