[Madoshakalaka#75] add initial CI config

still needs rules to run on scheduled/manual triggers

Signed-off-by: Bryant Finney <finneybp@gmail.com>

.gitlab/ci/main.yml

@@ -0,0 +1,35 @@
+# -------------------------------------------------------------------------------------
+# Summary: Define the root CI configuration for the project.
+# Created: 2021-11-06 22:17:22
+# Author:  Bryant Finney (https://bryant-finney.github.io/about)
+# -------------------------------------------------------------------------------------
+workflow:
+  # avoid duplicate/detached pipelines for merge requests
+  rules:
+    - if: $CI_MERGE_REQUEST_ID
+      when: never
+    - when: always
+
+update python images:
+  after_script: [docker logout $CI_REGISTRY]
+
+  before_script:
+    - docker login $CI_REGISTRY -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD
+
+  image: docker:20.10
+  needs: []
+
+  parallel:
+    matrix:
+      - PY_MAJOR: 3
+        PY_MINOR: [6, 7, 8]
+
+  script:
+    - docker pull $DOCKER_IMAGE
+    - docker tag $DOCKER_IMAGE $CI_REGISTRY_IMAGE/$DOCKER_IMAGE
+    - docker push $CI_REGISTRY_IMAGE/$DOCKER_IMAGE
+
+  services: ["docker:20.10-dind"]
+  stage: build
+  variables:
+    DOCKER_IMAGE: python:${PY_MAJOR}.${PY_MINOR}