fix(backend): improve Dockerfile multistep build (#1727)

* fix(backend): improve Dockerfile multistep build

* chore: update Dockerfile and entrypoint script to setup poetry correctly

* refactor: update Dockerfile to change working directory

---------

Co-authored-by: Gustavo Flores <gustavo.flores@profusion.mobi>

Author: AmadeusK525

backend/Dockerfile

@@ -1,50 +1,67 @@
 # syntax=docker/dockerfile:1
 
-# Create server docker image (all non-code dependencies)
-FROM alpine:3.20 as backend-base
-
-WORKDIR /
-
-ENV POETRY_HOME=/opt/poetry
+# Build stage: Install dependencies and build the application
+FROM alpine:3.20 as builder
+WORKDIR /backend
 
-RUN apk update \
-    && apk add --no-cache \
+RUN apk update && \
+    apk add --no-cache \
         python3 \
         python3-dev \
         gcc \
         libffi-dev \
         libc-dev \
         libpq-dev \
-        postgresql \
-        curl \
-    && python3 -m venv $POETRY_HOME \
-    && $POETRY_HOME/bin/pip install poetry==1.8.3 \
-    && ln -s $POETRY_HOME/bin/poetry /bin/poetry
-
-FROM backend-base
-COPY . /backend
-COPY ./utils/docker/entrypoint.sh /entrypoint.sh
-WORKDIR /backend
+        curl
+
+COPY pyproject.toml poetry.lock /backend/
+
+ENV POETRY_HOME=/opt/poetry \
+    POETRY_VIRTUALENVS_IN_PROJECT=1
+
+RUN python3 -m venv $POETRY_HOME
+RUN $POETRY_HOME/bin/pip install poetry==1.8.3
 
 ARG INSTALL_DEV_DEPS=false
 RUN if [ "$INSTALL_DEV_DEPS" = "true" ]; then \
-        poetry install --no-interaction; \
+        $POETRY_HOME/bin/poetry install --no-interaction; \
     else \
-        poetry install --no-interaction --only main; \
+        $POETRY_HOME/bin/poetry install --no-interaction --only main; \
     fi
 
-ENV DJANGO_APP="kernelCI"
+# Copy application code
+COPY . /backend/
 
 # Precompile Python modules
 RUN O='0 1 2' \
-        PY_MAJMIN=`poetry run python -c "import sys; print('%s.%s'%sys.version_info[0:2])"` \
-        PY_D=`poetry env info --path` \
-        D="$PY_D $DJANGO_APP"; \
+        PY_MAJMIN=`$POETRY_HOME/bin/poetry run python -c "import sys; print('%s.%s'%sys.version_info[0:2])"`  \
+        PY_D=`$POETRY_HOME/bin/poetry env info --path` \
+        D="$PY_D kernelCI"; \
         for N in $O; do \
             echo "compile python $PY_MAJMIN byte code at -O$N: $D"; \
-            PYTHONOPTIMIZE=$N poetry run python -m compileall -q $D || exit 1; \
+            PYTHONOPTIMIZE=$N $POETRY_HOME/bin/poetry run python -m compileall -q $D || exit 1; \
         done
 
+# Runtime stage: Create a clean image with only runtime dependencies
+FROM alpine:3.20 as app
+WORKDIR /backend
+
+# Install only runtime dependencies (no build tools)
+RUN apk update && \
+    apk add --no-cache \
+        python3 \
+        libpq \
+        postgresql-client \
+        curl
+
+COPY --from=builder /opt/poetry /opt/poetry
+COPY --from=builder /backend/.venv /backend/.venv
+
+ENV PATH="/backend/.venv/bin:/opt/poetry/bin:$PATH"
+
+COPY --from=builder /backend /backend
+COPY --from=builder /backend/utils/docker/entrypoint.sh /entrypoint.sh
+
 ARG BACKEND_VOLUME_DIR
 ENV BACKEND_VOLUME_DIR=${BACKEND_VOLUME_DIR}
 RUN echo "Building with volume on: $BACKEND_VOLUME_DIR"

backend/utils/docker/entrypoint.sh

@@ -2,7 +2,6 @@
 export PYTHONOPTIMIZE=${PYTHONOPTIMIZE:-2}
 export PYTHONUNBUFFERED=${PYTHONUNBUFFERED:-1}
 
-source $(poetry env info -C ./backend --path)/bin/activate
 set -e
 
 # usage: file_env VAR [DEFAULT]