ci: add automatic docker image building

.gitlab/ci/getRegistryBranch.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+
+# script returns string with everything after the last colon of $1 input
+echo -n $1 | grep -oE '[^:]+$'

.gitlab/ci/getRegistryTag.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env sh
+
+# script returns semantical versioning string linke 2.0.0 (if $1 is v2.0.0) or $1
+if echo -n $1 | grep -Eq 'v[0-9]+\.[0-9]+\.[0-9]+'; then 
+  echo $(echo -n "$1" | cut -c 2-);
+else 
+  echo $1;
+fi

.gitlab/ci/pushAsLatestVersion.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env sh
+
+# If this is a pipeline of a version tag, also push this version 
+# as latest to the registry alias $2:latest
+if echo -n $1 | grep -Eq 'v[0-9]+\.[0-9]+\.[0-9]+'; then
+  docker push $2:latest;
+fi

.gitlab/ci/testCIScripts.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env sh
+
+# test all CI scripts
+
+SCRIPT_DIR=$(dirname "$0")
+
+TAG_VERSION=$(sh $SCRIPT_DIR/getRegistryTag.sh "v1.0.0")
+TAG_TEST=$(sh $SCRIPT_DIR/getRegistryTag.sh "TEST")
+BRANCH_NAME=$(sh $SCRIPT_DIR/getRegistryBranch.sh "very:first:test")
+
+# Leaving out pushAsLatestVersion.sh as its controll flow
+# is based on the same condition as getRegistryTag.sh
+
+if [ $TAG_VERSION != "1.0.0" ]; then
+	echo "ERROR in CI SCRIPT: $SCRIPT_DIR/getRegistryTag.sh"
+	return 1
+fi
+
+if [ $TAG_TEST != "TEST" ]; then
+	echo "ERROR in CI SCRIPT: $SCRIPT_DIR/getRegistryTag.sh"
+	return 2
+fi
+
+if [ $BRANCH_NAME != "test" ]; then
+	echo "ERROR in CI SCRIPT: $SCRIPT_DIR/getRegistryBranch.sh"
+	return 3
+fi
+
+return 0