use --no-cache-dir flag to pip in dockerfiles to save space (robu…

…sta-dev#531)

using the "--no-cache-dir" flag in pip install, make sure downloaded packages
by pip don't cache on the system. This is a best practice that makes sure
to fetch from a repo instead of using a local cached one. Further, in the case
of Docker Containers, by restricting caching, we can reduce image size.
In terms of stats, it depends upon the number of python packages
multiplied by their respective size. e.g for heavy packages with a lot
of dependencies it reduces a lot by don't cache pip packages.

Further, more detailed information can be found at

https://medium.com/sciforce/strategies-of-docker-images-optimization-2ca9cc5719b6

Signed-off-by: Pratik Raj <rajpratik71@gmail.com>

Signed-off-by: Pratik Raj <rajpratik71@gmail.com>

Dockerfile

@@ -14,7 +14,7 @@ ENV ENV_TYPE=DEV
 
 # we install the project requirements and install the app in separate stages to optimize docker layer caching
 RUN mkdir /app
-RUN pip3 install --upgrade pip
+RUN pip3 install --no-cache-dir --upgrade pip
 RUN curl -sSL https://install.python-poetry.org | python3 -
 RUN /root/.local/bin/poetry config virtualenvs.create false
 COPY pyproject.toml poetry.lock /app/
@@ -23,19 +23,19 @@ WORKDIR /app
 # Install gcc to compile rumal.yaml.clib, wheel is missing.
 RUN apt-get update \
     && apt-get install -y --no-install-recommends gcc \
-    && pip3 install ruamel.yaml.clib \
+    && pip3 install --no-cache-dir ruamel.yaml.clib \
     && apt-get purge -y --auto-remove gcc \
     && rm -rf /var/lib/apt/lists/*
 
 RUN /root/.local/bin/poetry install --no-root --extras "all"
 
 COPY src/ /app/src
 
-RUN pip3 install .
+RUN pip3 install --no-cache-dir .
 
 COPY playbooks/ /etc/robusta/playbooks/defaults
 
-RUN python3 -m pip install /etc/robusta/playbooks/defaults
+RUN python3 -m pip install --no-cache-dir /etc/robusta/playbooks/defaults
 
 # -u disables stdout buffering https://stackoverflow.com/questions/107705/disable-output-buffering
-CMD [ "python3", "-u", "-m", "robusta.runner.main"]
+CMD [ "python3", "-u", "-m", "robusta.runner.main"]