set version for the docker build (#574)

Author: mr-c

.github/workflows/quay-publish.yml

@@ -13,6 +13,8 @@ jobs:
         id: image_tags
         run: |
           echo -n ::set-output name=IMAGE_TAGS::${GITHUB_REF#refs/*/}
+      - name: record schema-salad version
+        run: pip install setuptools_scm[toml] && python -m setuptools_scm
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
       - name: Login to Quay.io

schema_salad.Dockerfile

@@ -1,16 +1,18 @@
-FROM python:3.9-alpine as builder
+FROM alpine:latest as builder
 
 RUN apk add --no-cache git gcc python3-dev libc-dev
-
 WORKDIR /schema_salad
 COPY . .
 
-RUN pip install toml -rmypy-requirements.txt "$(grep ruamel requirements.txt)"
-RUN SCHEMA_SALAD_USE_MYPYC=1 MYPYPATH=mypy-stubs python3 setup.py bdist_wheel --dist-dir=/wheels
-RUN pip wheel -r requirements.txt --wheel-dir=/wheels
-RUN pip install --force-reinstall --no-index --no-warn-script-location --root=/pythonroot/ /wheels/*.whl
+RUN python3 -m venv env3
+RUN source env3/bin/activate && python3 -m pip install -U pip setuptools wheel build
+RUN export SETUPTOOLS_SCM_PRETEND_VERSION=$(grep __version__ schema_salad/_version.py  | awk -F\' '{ print $2 }') ; source env3/bin/activate && SCHEMA_SALAD_USE_MYPYC=1 MYPYPATH=mypy-stubs python3 -m build --wheel --outdir=/wheels
+RUN source env3/bin/activate && python3 -m pip wheel -r requirements.txt --wheel-dir=/wheels
+RUN source env3/bin/activate && python3 -m pip install --force-reinstall --no-index --no-warn-script-location --root=/pythonroot/ /wheels/*.whl
 
-FROM python:3.9-alpine as module
+FROM alpine:latest as module
 LABEL maintainer [email protected]
 
+RUN apk add --no-cache py3-six
+
 COPY --from=builder /pythonroot/ /