[gimp/wip/schumaml/add-ci-prepare-stage] build: try to add a custom docker image prepare stage

[Michael Schumacher <schumaml src gnome org>]

commit 23db27e4bf1e62595146e25a31a346b714945ac7
Author: Michael Schumacher <schumaml gmx de>
Date:   Fri May 29 15:40:53 2020 +0200

    build: try to add a custom docker image prepare stage

 .gitlab-ci.yml | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 0d74c2803b..20f4c96a66 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,6 +1,7 @@
 image: debian:testing
 
 stages:
+  - prepare
   - dependencies
   - gimp
   - analysis
@@ -11,10 +12,30 @@ variables:
   INSTALL_PREFIX: "${CI_PROJECT_DIR}/${INSTALL_DIR}"
   APT_CACHE: "${CI_PROJECT_DIR}/apt-cache"
 
+## prepare docker images ##
+
+build-image:
+  stage: prepare
+  variables:
+    GIT_STRATEGY: none
+  cache: {}
+  image:
+    name: gcr.io/kaniko-project/executor:debug
+    entrypoint: [""]
+  script:
+    - mkdir -p /kaniko/.docker
+    - echo 
"{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" 
> /kaniko/.docker/config.json
+    - echo "FROM debian/testing" > Dockerfile
+    - echo "RUN apt-get install -y --no-install-recommends \\" >> Dockerfile
+    - echo "at-spi2-core build-essential desktop-file-utils ffmpeg ghostscript git glib-networking 
gobject-introspection graphviz-dev gtk-doc-tools hicolor-icon-theme intltool iso-codes libappstream-glib-dev 
libbz2-dev libdbus-glib-1-dev libexif-dev libgexiv2-dev libgirepository1.0-dev libgtk-3-bin libgtk-3-dev 
libgudev-1.0-dev libjson-glib-dev liblcms2-dev liblzma-dev libmng-dev libmypaint-dev libopenexr-dev 
libpoppler-glib-dev libraw-dev libraw19 librsvg2-dev libspiro-dev libsuitesparse-dev libtiff-dev libtiff5-dev 
libtool libumfpack5 libwebp-dev libwmf-dev libxmu-dev libxpm-dev luajit meson mypaint-brushes poppler-data 
python3 valac xauth xvfb" >> Dockerfile
+
+    - /kaniko/executor --context $CI_PROJECT_DIR --dockerfile $CI_PROJECT_DIR/Dockerfile --destination 
$CI_REGISTRY_IMAGE:build-debian-latest --cache=true --cache-ttl=120h
+
 ## GNU/Linux 64-bit CIs ##
 
 deps-debian/testing:
   stage: dependencies
+  image: $CI_REGISTRY_IMAGE:build-debian-latest
   cache:
     paths:
     - apt-cache
@@ -68,6 +89,7 @@ deps-debian/testing:
 
 .gimp-debian/testing-base:
   stage: gimp
+  image: $CI_REGISTRY_IMAGE:build-debian-latest
   dependencies:
     - deps-debian/testing
   cache: