backend: Migrate build system to poetry

Since Poetry has better support for dependency management than using a
simple pip requirements file, Poetry is now used to fetch dependencies.
Also the versions are now more stricly given, since sometimes the most
up-to-date versions are not compatible with other up-to-date versions.

This happens with the new flask version 2.0.0, which came out this week
and break the build, since flask-restx is not working correctly with
flask 2.0.0

See python-restx/flask-restx#308

backend/Dockerfile

@@ -1,10 +1,22 @@
 FROM python:3.8-slim-buster
 WORKDIR /app
 
-COPY requirements.txt /app/requirements.txt
-RUN pip3 install -r requirements.txt
+ENV PYTHONFAULTHANDLER=1 \
+  PYTHONUNBUFFERED=1 \
+  PYTHONHASHSEED=random \
+  PIP_NO_CACHE_DIR=off \
+  PIP_DISABLE_PIP_VERSION_CHECK=on \
+  PIP_DEFAULT_TIMEOUT=100 \
+  POETRY_VERSION=1.1.6 \
+  GUNICORN_VERSION=20.1.0
 
-RUN pip3 install gunicorn
+RUN pip install poetry==$POETRY_VERSION gunicorn==$GUNICORN_VERSION
+
+# copy requirements first for caching
+COPY poetry.lock pyproject.toml /app/
+
+RUN poetry config virtualenvs.create false \
+ && poetry install --no-dev --no-interaction --no-ansi
 
 COPY . /app/backend
 CMD ["gunicorn", "--bind=0.0.0.0:5000", "backend.wsgi:app"]

backend/README.md

@@ -1,10 +1,15 @@
 # Backend service
 
 ## Setup dev environment
+Requirements:
+ - Python > 3.8 is installed
+ - Poetry is installed (https://python-poetry.org/docs/)
+
 ```
 pip3 install virtualenv
 virtualenv venv
-pip3 install -r requirements.txt
+source venv/bin/activate
+poetry install
 ```
 
 ## Startup in development

backend/pyproject.toml

@@ -0,0 +1,21 @@
+[tool.poetry]
+name = "openenergize-backend"
+version = "0.1.0"
+description = ""
+authors = ["Jan Bucher <jan@bucher.cloud>"]
+
+[tool.poetry.dependencies]
+python = "^3.8"
+Flask = "^1.1.4"
+flask-restx = "^0.4.0"
+requests = "^2.25.1"
+PyYAML = "^5.4.1"
+pymodbus = "^2.5.2"
+cachetools = "^4.2.2"
+
+[tool.poetry.dev-dependencies]
+pytest = "^6.2.4"
+
+[build-system]
+requires = ["poetry-core>=1.0.0"]
+build-backend = "poetry.core.masonry.api"