Fix Docker build

Author: Programie

.gitlab-ci.yml

@@ -24,6 +24,13 @@ stages:
     - php composer.phar install
     - vendor/bin/phpunit --coverage-text --colors=never
 
+.docker:
+  image: docker:18.09.7
+  services:
+    - docker:18.09.7-dind
+  before_script:
+    - echo -n $CI_JOB_TOKEN | docker login -u gitlab-ci-token --password-stdin $CI_REGISTRY
+
 test:7.3:
   extends: .tests
   image: php:7.3
@@ -51,12 +58,11 @@ build_package:
       - README.md
 
 Docker Build:
-  image: docker:18
+  extends: .docker
   stage: build_image
   dependencies:
   - build_package
   script:
-    - echo -n $CI_JOB_TOKEN | docker login -u gitlab-ci-token --password-stdin $CI_REGISTRY
     # fetches the latest image (not failing if image is not found)
     - docker pull $CI_REGISTRY_IMAGE:latest || true
     # builds the project and passes vcs vars for LABEL
@@ -76,7 +82,7 @@ Docker Build:
 
 # Here, the goal is to tag the "master" branch as "latest"
 Push Docker latest:
-  image: docker:18
+  extends: .docker
   variables:
     # We are just playing with Docker here.
     # We do not need GitLab to clone the source code.
@@ -86,7 +92,6 @@ Push Docker latest:
     # Only "master" should be tagged "latest"
     - master
   script:
-    - echo -n $CI_JOB_TOKEN | docker login -u gitlab-ci-token --password-stdin $CI_REGISTRY
     # Because we have no guarantee that this job will be picked up by the same runner
     # that built the image in the previous step, we pull it again locally
     - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
@@ -98,7 +103,7 @@ Push Docker latest:
 # Finally, the goal here is to Docker tag any Git tag
 # GitLab will start a new pipeline everytime a Git tag is created, which is pretty awesome
 Push Docker tag:
-  image: docker:18
+  extends: .docker
   variables:
     # Again, we do not need the source code here. Just playing with Docker.
     GIT_STRATEGY: none
@@ -107,7 +112,6 @@ Push Docker tag:
     # We want this job to be run on tags only.
     - tags
   script:
-    - echo -n $CI_JOB_TOKEN | docker login -u gitlab-ci-token --password-stdin $CI_REGISTRY
     - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA
     - docker tag $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
     - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME