fix: use wheel-based build to fix bytecode staleness

The sidecar uses a read-only filesystem which prevents Python from
creating bytecode at runtime. The previous approach pre-compiled
bytecode in a separate base image, but timestamps were corrupted
when files were copied between Docker stages, causing Python to
mark the bytecode as stale and recompile on every invocation.

This change builds Python dependencies as wheels in a pythonbuilder
stage using BuildKit cache mounts, then installs them in the final
python:3.13-slim-trixie stage using a bind mount. Wheels include
pre-compiled bytecode with correct timestamps. The bind mount keeps
wheels out of final layers, and the distroless complexity is
eliminated.

After wheel installation, we run compileall to ensure all Python
bytecode is freshly compiled with correct timestamps, preventing
any stale bytecode from remaining in the final image.

The separate barmanbase image, its workflow, and related Renovate
configuration are no longer needed and have been removed.

Closes #711
Closes #735

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>

.github/workflows/barman-base-image.yml

@@ -1,38 +0,0 @@
-name: Barman Base Image
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: "0 0 * * 0"
-  push:
-    branches:
-      - main
-    paths:
-      - 'containers/sidecar-requirements.txt'
-
-permissions: read-all
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    permissions:
-      packages: write
-      contents: write
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v6
-      - name: Install QEMU static binaries
-        uses: docker/setup-qemu-action@v3
-      - name: Install Task
-        uses: arduino/setup-task@v2
-      - name: Install Dagger
-        env:
-          # renovate: datasource=github-tags depName=dagger/dagger versioning=semver
-          DAGGER_VERSION: 0.19.10
-        run: |
-          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=$HOME/.local/bin sh
-      - name: Publish a barman-base
-        env:
-          REGISTRY_USER: ${{ github.actor }}
-          REGISTRY_PASSWORD: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          task publish-barman-base

Taskfile.yml

@@ -381,34 +381,6 @@ tasks:
         build --dir . --file containers/Dockerfile.sidecar --platform linux/amd64 --platform linux/arm64
         publish --ref {{.SIDECAR_IMAGE_NAME}} --tags {{.IMAGE_VERSION}}
 
-  publish-barman-base:
-    desc: Build and publish a barman-cloud base container image
-    vars:
-      BARMAN_BASE_IMAGE_NAME: ghcr.io/{{.GITHUB_REPOSITORY}}-base{{if not (hasPrefix "refs/heads/main" .GITHUB_REF)}}-testing{{end}}
-      BARMAN_VERSION:
-        sh: grep "^barman" containers/sidecar-requirements.in | sed -E 's/.*==([^ ]+)/\1/'
-      BUILD_DATE:
-        sh: date +"%Y%m%d%H%M"
-    requires:
-      # We expect this to run in a GitHub workflow, so we put a few GitHub-specific vars here
-      # to prevent running this task locally by accident.
-      vars:
-        - CI
-        - GITHUB_REPOSITORY
-        - GITHUB_REF
-        - GITHUB_REF_NAME
-        - REGISTRY_USER
-        - REGISTRY_PASSWORD
-    env:
-      # renovate: datasource=git-refs depName=docker lookupName=https://github.com/purpleclay/daggerverse currentValue=main
-      DAGGER_DOCKER_SHA: ee12c1a4a2630e194ec20c5a9959183e3a78c192
-    cmds:
-      - >
-        dagger call -m github.com/purpleclay/daggerverse/docker@${DAGGER_DOCKER_SHA}
-        --registry ghcr.io --username $REGISTRY_USER --password env:REGISTRY_PASSWORD
-        build --dir . --file containers/Dockerfile.barmanbase --platform linux/amd64 --platform linux/arm64
-        publish --ref {{.BARMAN_BASE_IMAGE_NAME}} --tags "{{.BARMAN_VERSION}}-{{.BUILD_DATE}}"
-
   controller-gen:
     desc: Run controller-gen
     run: once

containers/Dockerfile.barmanbase

@@ -1,7 +0,0 @@
-FROM python:3.13-slim-bookworm
-COPY containers/sidecar-requirements.txt .
-RUN apt-get update && \
-    apt-get install -y postgresql-common build-essential && \
-    /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh -y && \
-    apt-get install -y libpq-dev && \
-    pip install -r sidecar-requirements.txt

containers/Dockerfile.sidecar

@@ -2,7 +2,7 @@
 # The container needs to provide and build two components:
 # * barman-cloud
 # * instance plugin
-# Both components are built before going into a distroless container
+# Both components are built before going into the final container
 
 # Build the manager binary
 FROM --platform=$BUILDPLATFORM golang:1.25.6 AS gobuilder
@@ -33,19 +33,27 @@ COPY ../internal/ internal/
 RUN --mount=type=cache,target=/go/pkg/mod --mount=type=cache,target=/root/.cache/go-build \
     CGO_ENABLED=0 GOOS=${TARGETOS:-linux} GOARCH=${TARGETARCH} go build -a -o manager cmd/manager/main.go
 
-# Use plugin-barman-cloud-base to get the dependencies.
-# pip will build everything inside /usr, so we copy every file into a new
-# destination that will then be copied into the distroless container
-FROM ghcr.io/cloudnative-pg/plugin-barman-cloud-base:3.17.0-202601131704 AS pythonbuilder
-# Prepare a new /usr/ directory with the files we'll need in the final image
-RUN mkdir /new-usr/ && \
-    cp -r --parents /usr/local/lib/ /usr/lib/*-linux-gnu/ /usr/local/bin/ \
-    /new-usr/
+# Build wheel files for Python dependencies
+FROM python:3.13-slim-trixie AS pythonbuilder
+WORKDIR /build
 
-# Joint process
-# Now we put everything that was build from the origin into our
-# distroless container
-FROM gcr.io/distroless/python3-debian12:nonroot
+# Install build dependencies
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        postgresql-common \
+        build-essential && \
+    /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh -y && \
+    apt-get install -y --no-install-recommends libpq-dev
+
+# Copy requirements
+COPY containers/sidecar-requirements.txt .
+
+# Build wheels with pip cache mount
+RUN --mount=type=cache,target=/root/.cache/pip \
+    pip wheel --wheel-dir=/wheels -r sidecar-requirements.txt
+
+# Final sidecar image
+FROM python:3.13-slim-trixie
 
 ENV SUMMARY="CloudNativePG Barman plugin" \
     DESCRIPTION="Container image that provides the barman-cloud sidecar"
@@ -60,7 +68,23 @@ LABEL summary="$SUMMARY" \
       version="" \
       release="1"
 
-COPY --from=pythonbuilder /new-usr/* /usr/
+# Install runtime dependencies
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        postgresql-common && \
+    /usr/share/postgresql-common/pgdg/apt.postgresql.org.sh -y && \
+    apt-get install -y --no-install-recommends libpq5 && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+# Install wheels using bind mount (wheels not included in final layers)
+# and ensure all Python bytecode is freshly compiled with correct timestamps
+RUN --mount=type=bind,from=pythonbuilder,source=/wheels,target=/wheels \
+    pip install --no-cache-dir /wheels/*.whl && \
+    python -m compileall -q
+
+# Copy Go manager binary
 COPY --from=gobuilder /workspace/manager /manager
+
 USER 26:26
 ENTRYPOINT ["/manager"]

renovate.json5

@@ -79,12 +79,6 @@
     enabled: false,
   },
   packageRules: [
-    {
-      matchPackageNames: [
-       'ghcr.io/cloudnative-pg/plugin-barman-cloud-base',
-      ],
-      versioning: 'loose',
-    },
     {
       matchDatasources: [
         'go',