Change mechanics of Docker image build and usage

- Introduce a GH Action to build Docker image for docs generation every time the Dockerfile is changed
- Trigger docs generation when a new Docker image was built
- Minor fix in Dockerfile to avoid outdated apt database

Signed-off-by: Peter Goetz <pego@amazon.com>

.github/workflows/build-docker-image-docs.yml

@@ -0,0 +1,26 @@
+name: Build Docker image (docs)
+
+on:
+  push:
+    branches: [main]
+    paths: ['docs/Dockerfile']
+  pull_request:
+    branches: [main]
+    paths: ['docs/Dockerfile']
+
+jobs:
+  build-and-push-docker-image:
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+    steps:
+      - uses: actions/checkout@v2
+        name: Checkout repository
+
+      - uses: pmorelli92/github-container-registry-build-push@2.0.0
+        name: Build and Publish latest service image
+        with:
+          github-push-secret: ${{secrets.GITHUB_TOKEN}}
+          docker-image-name: dowhy-docs-generation
+          docker-image-tag: latest # optional
+          dockerfile-path: ./docs/Dockerfile # optional

.github/workflows/docs.yml

@@ -3,12 +3,16 @@ on:
   push:
     branches:
       - main
+  workflow_run:
+    workflows: [ "Build Docker image used for docs generation" ]
+    types:
+      - completed
+
 jobs:
   docs:
     runs-on: ubuntu-latest
     container:
-      image: darthtrevino/dowhy-docs
-      
+      image: "ghcr.io/${{ github.repository_owner }}/dowhy-docs-generation:latest"
     steps:
       - uses: actions/checkout@main
         with:

docs/Dockerfile

@@ -2,9 +2,9 @@
 # This dockerfile was used to generate darthtrevino/dowhy-docs, used in the 
 # build-and-publish-docs.yml workflow
 #
-FROM pego/dowhy-examples-notebooks-deps
+FROM ghcr.io/py-why/dowhy-example-notebooks-deps
 
 RUN apt update
 RUN DEBIAN_FRONTEND=noninteractive apt install --yes --quiet curl
 RUN curl -sSL https://install.python-poetry.org | python3 - --version 1.2.1
-ENV PATH=$PATH:/root/.local/share/pypoetry/venv/bin
+ENV PATH=$PATH:/root/.local/share/pypoetry/venv/bin