Container build without Docker

With this MR we use Kaniko instead of Docker to build our images. This way, we can also build and push them without Docker-in-Docker.

.gitlab-ci.yml

@@ -4,6 +4,10 @@ stages:
   - check
   - deploy
 
+default:
+  tags:
+    - exec-docker
+
 .dind:
   tags:
     - exec-dind
@@ -19,11 +23,10 @@ stages:
 
 lint-helm:
   stage: check
+  needs: []
   image:
     name: alpine/helm:3.5.2
     entrypoint: [""]
-  tags:
-    - exec-docker
   script: helm lint helm/
 
 
@@ -31,8 +34,6 @@ lint-helm:
 
 .benchmarks:
   image: openjdk:11-jdk
-  tags:
-    - exec-docker
   variables:
     GRADLE_OPTS: "-Dorg.gradle.daemon=false"
   cache:
@@ -217,8 +218,6 @@ deploy-uc4-load-generator:
   image:
     name: ghcr.io/graalvm/native-image:java11-21.1.0
     entrypoint: [""]
-  tags:
-    - exec-docker
   variables:
     GRADLE_OPTS: "-Dorg.gradle.daemon=false"
   cache:
@@ -320,10 +319,11 @@ deploy-theodolite-kaniko:
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
+  before_script:
+    - mkdir -p /kaniko/.docker
+    - echo "{\"auths\":{\"${CR_HOST}\":{\"auth\":\"$(printf "%s:%s" "${CR_USER}" "${CR_PW}" | base64 | tr -d '\n')\"}}}" > /kaniko/.docker/config.json
   script:
     - DOCKER_TAG_NAME=$(echo $CI_COMMIT_REF_SLUG- | sed 's/^master-$//')
-    - mkdir -p /kaniko/.docker
-    - echo "{\"auths\":{\"$CR_HOST\":{\"username\":\"$CR_USER\",\"password\":\"$CR_PW\"}}}" > /kaniko/.docker/config.json
     - /kaniko/executor --context $PWD --dockerfile $PWD/src/main/docker/Dockerfile.jvm -d $CR_HOST/$CR_ORG/theodolite:${DOCKER_TAG_NAME}latest-kaniko
   rules:
     - if: "$CR_HOST && $CR_ORG && $CR_USER && $CR_PW && $CI_COMMIT_TAG"
@@ -341,9 +341,8 @@ deploy-theodolite-kaniko:
 
 test-slo-checker-lag-trend:
   stage: test
+  needs: []
   image: python:3.7-slim
-  tags:
-    - exec-docker
   script:
     - cd slo-checker/record-lag
     - pip install -r requirements.txt
@@ -352,9 +351,8 @@ test-slo-checker-lag-trend:
 
 test-slo-checker-dropped-records-kstreams:
   stage: test
+  needs: []
   image: python:3.7-slim
-  tags:
-    - exec-docker
   script:
     - cd slo-checker/dropped-records
     - pip install -r requirements.txt