Add gitlab CI

* Add a pipeline that runs a yocto build:
  * setup the executor with ssh keys and install repo tool
  * checkout the manifest and get the layers
  * update the meta-guf layer that triggered the pipeline to the
  triggering commit
  * run a yocto build
  * copy build artifacts to the artifacts dir on the host

.gitlab-ci-template.yml

+image:
+  name: "crops/poky:ubuntu-20.04"
+  # Override entrypoint so we can pass --id to set the UID and GID for the user that is created in the container.
+  # This is a feature of the crops/poky images. See poky-entry.py for details.
+  entrypoint: ["/usr/bin/distro-entry.sh", "/usr/bin/dumb-init", "--", "/usr/bin/poky-entry.py", "--id=118:998"]
+
+stages:
+  - prepare
+  - build
+  - deploy
+
+variables:
+    GIT_STRATEGY: none
+    MANIFEST_URL: "git@gitlab.com:garz-fricke/yocto/manifest.git"
+    REPODIR: ${CI_PROJECT_DIR}/.repo
+
+.setup_ssh: &setup_ssh
+    # setup ssh key to access private repos, see https://docs.gitlab.com/ee/ci/ssh_keys/#ssh-keys-when-using-the-docker-executor
+    - eval $(ssh-agent -s)
+    - echo "$JENKINSGUF_SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
+    - mkdir -p ~/.ssh
+    - chmod 700 ~/.ssh
+    # add content of variable SSH_KNOWN_HOSTS to known hosts, see https://docs.gitlab.com/ee/ci/ssh_keys/#verifying-the-ssh-host-keys
+    - echo "$SSH_KNOWN_HOSTS" >> ~/.ssh/known_hosts
+    - chmod 644 ~/.ssh/known_hosts
+
+.repo_install: &repo_install
+    # install repo tool
+    - cd ~
+    - wget "https://raw.githubusercontent.com/GerritCodeReview/git-repo/v2.8/repo"
+    - chmod a+x repo
+
+.repo_checkout: &repo_checkout
+    # setup build dir
+    - cd ${CI_PROJECT_DIR}
+    - ~/repo init -u ${MANIFEST_URL} -b ${CI_DEFAULT_BRANCH}
+    - ~/repo sync --force-sync
+
+.checkout_commit: &checkout_commit
+    # checkout the commit that triggered the pipeline
+    - cd ${CI_PROJECT_DIR}/sources/${CI_PROJECT_NAME}
+    - git fetch origin
+    - git checkout ${CI_COMMIT_SHA}
+
+.repo_tag: &repo_tag
+    # create a manifest containing all fixed revisions
+    - ~/repo manifest -r > ${REPODIR}/manifests/default.xml.tagged
+
+prepare_environment:
+  tags:
+    - builds
+  stage: prepare
+  before_script:
+    - *setup_ssh
+  script:
+    - *repo_install
+    - *repo_checkout
+    - *checkout_commit
+    - *repo_tag
+  artifacts:
+    expire_in: 3h
+    paths:
+      - "*"
+  cache:
+    untracked: false
+    key:
+      files:
+        - .repo/manifests/default.xml
+      prefix: layers
+    paths:
+      - "sources/*/{[^.git]}*/*"
+
+.build:
+  tags:
+    - builds
+  stage: build
+  variables:
+    SETUPSCRIPT: "setup-environment"
+    IMAGEPATH: "tmp/deploy/images"
+    INSTALLSCRIPT: "fng-install.sh"
+  before_script:
+    - *setup_ssh
+  script:
+    # setup build environment
+    - export MACHINE="${CI_PARAM_MACHINE}"
+    - export DISTRO="${CI_PARAM_DISTRO}"
+    - source ./"${SETUPSCRIPT}" build
+    # start build
+    - echo -e "section_start:`date +%s`:bitbake_run\r\e[0KBitbake Log"
+    - bitbake "${CI_PARAM_IMAGE}"
+    - echo -e "section_end:`date +%s`:bitbake_run\r\e[0K"
+    # print install instructions
+    - |-
+        if [[ -f "${IMAGEPATH}/${CI_PARAM_MACHINE}/${INSTALLSCRIPT}" ]]; then
+          echo -e "Install the image:"
+          echo -e "export TFTP=\"${CI_SERVER_URL}/${CI_PROJECT_NAMESPACE}/${CI_PROJECT_NAME}/-/jobs/${CI_JOB_ID}/artifacts/raw/build/tmp/deploy/images/${CI_PARAM_MACHINE}\""
+          echo -e "curl \$TFTP/${INSTALLSCRIPT} | sh"
+        fi
+  parallel:
+    matrix:
+      - CI_PARAM_MACHINE: [imx6guf]
+        CI_PARAM_DISTRO: [guf-wayland]
+        CI_PARAM_IMAGE: [guf-image]
+  artifacts:
+    paths:
+      - "build/tmp/deploy/images/**/*"
+
+deploy_local:
+  tags:
+    - builds
+  stage: deploy
+  variables:
+    GIT_STRATEGY: none
+  script:
+    - mkdir -p /artifacts/${CI_PIPELINE_ID}/
+    - ls -al ${CI_PROJECT_DIR}
+    - cp -a build/tmp/deploy/images/* /artifacts/${CI_PIPELINE_ID}/
+    - echo -e "Artifacts are stored at http://${CI_RUNNER_DESCRIPTION##builds@}/gitlab_artifacts/${CI_PIPELINE_ID}/"

.gitlab-ci.yml

+include:
+  - local: '.gitlab-ci-template.yml'
+
+# use the .build template and specify which MACHINE/IMAGE/DISTO matrix to build
+build:
+  extends: .build
+  parallel:
+    matrix:
+      - CI_PARAM_MACHINE: [imx6guf]
+        CI_PARAM_DISTRO: [guf-wayland]
+        CI_PARAM_IMAGE: [guf-image]