Ditch builder and base Docker images

This should make dependency upgrades easier and bring more clarity to the CI pipelines

.drone.yml

@@ -15,16 +15,18 @@ trigger:
 
 steps:
   - name: install-lint-test
-    image: git.wtf-eg.de/kompetenzinventar/builder:1.0.2
+    image: python:3.8.18-alpine
+    env:
+      PYROOT: '/pyroot'
+      PYTHONUSERBASE: '/pyroot'
     commands:
+      - apk add --no-cache gcc g++ musl-dev python3-dev
+      - pip3 install pipenv
       - pipenv install --dev
       - pipenv run flake8
       - pipenv run reuse lint
       - pipenv run python -m unittest discover ki
 
-image_pull_secrets:
-  - dockerconfig
-
 ---
 kind: pipeline
 type: docker
@@ -91,8 +93,13 @@ trigger:
 
 steps:
   - name: install-lint-test
-    image: git.wtf-eg.de/kompetenzinventar/builder:1.0.2
+    image: python:3.8.18-alpine
+    env:
+      PYROOT: '/pyroot'
+      PYTHONUSERBASE: '/pyroot'
     commands:
+      - apk add --no-cache gcc g++ musl-dev python3-dev
+      - pip3 install pipenv
       - pipenv install --dev
       - pipenv run flake8
       - pipenv run reuse lint

Dockerfile

@@ -2,7 +2,17 @@
 #
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
-FROM git.wtf-eg.de/kompetenzinventar/builder:1.0.2 as builder
+FROM python:3.8.18-alpine as builder
+
+ENV PYROOT /pyroot
+ENV PYTHONUSERBASE $PYROOT
+
+RUN apk add --no-cache \
+    gcc \
+    g++ \
+    musl-dev \
+    python3-dev && \
+    pip3 install pipenv
 
 COPY Pipfile* ./
 
@@ -10,7 +20,10 @@ RUN PIP_USER=1 PIP_IGNORE_INSTALLED=1 pipenv install --system --deploy --ignore-
 RUN pip3 uninstall --yes pipenv
 
 
-FROM git.wtf-eg.de/kompetenzinventar/base:1.0.2 as ki-backend
+FROM python:3.8.18-alpine as ki-backend
+
+ENV PYROOT /pyroot
+ENV PYTHONUSERBASE $PYROOT
 
 # Install six explicitly. Otherwise Python complains about it missing.
 RUN pip3 install six