Pin the Docker image version & upgrade Poetry (#296)

* Pin the Docker image version & upgrade Poetry

* Add a docker build step to CI to make sure this keeps working

* Checkout the code so we have something to build

.github/workflows/ci.yml

@@ -88,3 +88,16 @@ jobs:
     - name: Run ${{ matrix.toxenv }}
       run: |
         tox -vv -e ${{ matrix.toxenv }}
+  docker:
+    name: Build Docker Image
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f
+      name: Checkout the repo
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@94ab11c41e45d028884a99163086648e898eed25
+      with:
+        install: true
+    - name: Build
+      run: |
+        docker build .

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3-alpine as base
+FROM python:3-alpine3.14 as base
 
 WORKDIR /app
 
@@ -7,7 +7,7 @@ FROM base as builder
 ENV PIP_DEFAULT_TIMEOUT=100 \
     PIP_DISABLE_PIP_VERSION_CHECK=1 \
     PIP_NO_CACHE_DIR=1 \
-    POETRY_VERSION=1.1.2
+    POETRY_VERSION=1.1.12
 
 RUN apk add --no-cache cargo gcc libffi-dev musl-dev openssl-dev rust libgit2-dev
 RUN pip --no-cache-dir install "poetry==$POETRY_VERSION"