Use standard m2 repository cacheing

.gitlab-ci.yml

@@ -2,17 +2,28 @@ image:
   maven:3.3.9-jdk-8
 
 variables:
-  # This will supress any download for dependencies and plugins or upload messages which would clutter the console log.
-  # `showDateTime` will show the passed time in milliseconds. You need to specify `--batch-mode` to make this work.
-  #MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
-  # This variant is compatible with GitLab 9.0.0 with the 9.0.0 runner,
-  # as explicit path cacheing seems to be temporarily broken in that release
-  MAVEN_OPTS: "-Dmaven.repo.local=/cache/inc-mda/.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
+  #
+  # maven.repo.local points Maven at a local repository, which will
+  # be cached across runs.
+  #
+  # `showDateTime` will show the passed time in milliseconds. You need to
+  # specify `--batch-mode` to make this work.
+  #
+  # The other two defines will supress any download for dependencies and
+  # plugins or upload messages which would clutter the console log.
+  #
+  MAVEN_OPTS: "-Dmaven.repo.local=.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
   # As of Maven 3.3.0 instead of this you may define these options in `.mvn/maven.config` so the same config is used
   # when running from the command line.
   # `installAtEnd` and `deployAtEnd`are only effective with recent version of the corresponding plugins.
   MAVEN_CLI_OPTS: "--batch-mode --errors --fail-at-end --show-version -DinstallAtEnd=true -DdeployAtEnd=true"
 
+# Cache the Maven repository across runs.
+cache:
+  key: ${CI_BUILD_REF_NAME}
+  paths:
+    - .m2
+
 test:
   tags:
     - linux