Recently I needed to dockerize an application for a virtual onprem. However, at the end of my project I ended up with a docker image that was 8.4 GB. This is HUGE in terms of size for a container. Thus, I went on a short journey to minimize the image using the following techniques.
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Prevent APT from installing recommended packages by adding the following parameter to every apt-get install command:
--no-install-recommends. -
Added a
.dockerignorefile. This allows one to define a list of folders/file globs to ignore when building your Dockerfile. -
Reduced the amount of layers by merging related commands.
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Clean up apt cache via:
&& rm -rf /var/lib/apt/lists/*. -
Used dive to inspect my image layers to analyze and remove extra unused packages/files.
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I stumbled across a tool docker-slim that can supposedly reduce a container's size by up to 30x.
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Check your base image. Think about running an alpine version of the container if you haven't already.
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Use multistage builds.
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Use your layers wisely. Put commands that are more likely to change towards the bottom.
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Lint your Dockerfile using FromLatest
Sources:
- https://ubuntu.com/blog/we-reduced-our-docker-images-by-60-with-no-install-recommends
- https://towardsdatascience.com/slimming-down-your-docker-images-275f0ca9337e
Originally Posted on dev.to