fix(ci): Changed GitLab CI Build Tool to Kaniko for Rootless Runners

.github/gitlab/ci.yaml

 # Author: Kabir Kwatra <kabir@kwatra.me>
 
-image: docker:19
-services: ["docker:19-dind"]
-variables:
-  DOCKER_TLS_CERTDIR: "/certs"
-
 stages: [build]
 
-before_script:
-  - docker info
-  - echo -n $CI_JOB_TOKEN | docker login -u gitlab-ci-token --password-stdin $CI_REGISTRY
-
 build:
   stage: build
+  image:
+    name: gcr.io/kaniko-project/executor:debug
+    entrypoint: [""]
   script:
-    - docker pull $CI_REGISTRY_IMAGE:latest || true
+    - mkdir -p /kaniko/.docker
+    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
     - >
       for containerfile_path in $(ls .github/containerfiles/*.Containerfile); do
         containerfile_name=${containerfile_path##*/}
         container_tag=${containerfile_name%%.*}
         container_fulltag="$CI_REGISTRY_IMAGE:$container_tag"
         echo "Building $containerfile_name with tag $container_fulltag"
-        docker build \
+        /kaniko/executor \
+          --context $CI_PROJECT_DIR \
+          --dockerfile $containerfile_path \
           --build-arg BUILD_DATE=`date -u +"%Y-%m-%dT%H:%M:%SZ"` \
           --build-arg VCS_REF=`git rev-parse --short HEAD` \
           --build-arg OCI_SRC_URL=$CI_PROJECT_URL \
-          --cache-from $container_fulltag \
-          -f $containerfile_path \
-          -t $container_fulltag \
-          .
-        docker push $container_fulltag
+          --destination $container_fulltag
       done