Automate container creation on release (#304)

This is based on the Dockerfile provided at #284 with some
tweaks.

Makefile is adjusted to allow easy experimentation, but the
primary work here uses github actions.

The container is built any time a tag that looks like a
semver is pushed. This is in alignment with the existing
release handling.

.github/workflows/docker.yaml

@@ -0,0 +1,43 @@
+name: docker
+
+
+on:
+  push:
+    tags:
+      - '[2-9].[0-9]+.[0-9]+'
+
+
+jobs:
+  push_to_registry:
+    name: Push Docker image to Docker Hub
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: cdent/gabbi
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+
+      
+      - name: Build and push Docker image
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          build-args:
+            GABBI_VERSION=${{steps.meta.outputs.version}}

Dockerfile

@@ -0,0 +1,9 @@
+FROM python:3-alpine
+MAINTAINER Chris Dent <cdent@anticdent.org>
+
+ARG GABBI_VERSION
+RUN python -m venv /app
+COPY . /app/
+RUN cd /app && PBR_VERSION=${GABBI_VERSION} /app/bin/pip --no-cache-dir install .
+
+ENTRYPOINT ["/app/bin/python", "-m", "gabbi.runner"]

Makefile

@@ -1,6 +1,8 @@
 # simple Makefile for some common tasks
 .PHONY: clean test dist release pypi tagv docs
 
+gabbi-version := $(shell python -c 'import gabbi; print gabbi.__version__')
+
 clean:
 	find . -name "*.pyc" |xargs rm || true
 	rm -r dist || true
@@ -12,9 +14,7 @@ clean:
 	rm -r gabbi.egg-info || true
 
 tagv:
-	git tag -s \
-		-m `python -c 'import gabbi; print gabbi.__version__'` \
-		`python -c 'import gabbi; print gabbi.__version__'`
+	git tag -s -m ${gabbi-version} ${gabbi-version}
 	git push origin main --tags
 
 cleanagain:
@@ -41,3 +41,6 @@ release: clean test cleanagain tagv pypi
 pypi:
 	python3 setup.py sdist bdist_wheel
 	twine upload -s dist/*
+
+docker:
+	docker build --build-arg GABBI_VERSION=${gabbi-version} -t gabbi:${gabbi-version} .

docs/source/index.rst

@@ -125,4 +125,11 @@ Python 3 comes with a built-in tool to create virtual environments::
 This way we can later use ``deactivate`` and safely remove the ``venv``
 directory, thus erasing any trace of gabbi from the system.
 
+If you prefer to not install gabbi, or perhaps want to use it in a dynamic
+fashion in a CI setting, there is an official container image hosted at
+`docker hub`_ as ``cdent/gabbi``. It allows running :doc:`gabbi-run <runner>`
+with any arguments you might need, providing tests on STDIN of via a mounted
+volume.
+
+.. _docker hub: https://hub.docker.com/repository/docker/cdent/gabbi
 .. _virtualenv: https://virtualenv.pypa.io