Refactoring/improve comments and readme (#15)

* Explain why PR trigger event does not push new container image to registry

* Update README

* Specify explicitly push and eventFilterForPush for educational purposes

.github/workflows/lint-format-typecheck.yaml

@@ -42,6 +42,11 @@ jobs:
       uses: devcontainers/[email protected]
       with:
         imageName: ghcr.io/${{ secrets.GH_DOCKER_REGISTRY_NAMESPACE }}/${{ vars.CONTAINER_IMAGE_NAME }}
+        # Push new container image if `eventFilterForPush` and `refFilterForPush` (by default allow all branches to trigger a push of the container image) are true
+        push: filter
+        # Push new image only if event name that triggered this workflow matches `push`
+        # If a pull request triggered it, then skip pushing new container image to registry
+        eventFilterForPush: push
         runCmd: |
           poetry run ruff check --fix
           poetry run ruff format .

.github/workflows/pytest.yaml

@@ -41,5 +41,7 @@ jobs:
       uses: devcontainers/[email protected]
       with:
         imageName: ghcr.io/${{ secrets.GH_DOCKER_REGISTRY_NAMESPACE }}/${{ vars.CONTAINER_IMAGE_NAME }}
+        push: filter
+        eventFilterForPush: push
         runCmd: |
           poetry run pytest

README.md

@@ -48,8 +48,8 @@ Note that in step 3, the devcontainer is not rebuilt, but reused from the latest
 
 ### 2. Open a PR with a new feature
 
-Similar to scenario 1, but pushing new devcontainer image is _skipped_ because the code changes are not merged to main ([see specification of](https://github.com/devcontainers/ci/blob/main/docs/github-action.md#inputs) `push` and `eventFilterForPush` inputs for `devcontainer/ci` action).
+Similar to scenario 1, but pushing new devcontainer image is _skipped_ because the workflow has not been triggered by a push to main, rather a PR event (for more [see specification of](https://github.com/devcontainers/ci/blob/main/docs/github-action.md#inputs) `push`, `refFilterForPush`, and `eventFilterForPush` (default) inputs for `devcontainer/ci` action).
 
 ### 3. Add new Python libraries to the list of existing dependencies
 
-If we were to add a new Python library as part of our development, in step 4 of scenario 1 we would not get the virtual environment from the cache, but we would use the newly created one with the additional library and _push_ it to the cache.
+If we were to add a new Python library as part of our development, in step 4 of scenario 1 we would not get the virtual environment from the cache, but we would use the newly created one with the additional library and _push_ it to the cache.