Making use of the existing layer cache as frequently as possible is key to speeding up Docker image builds. The less work we have to redo across builds, the faster our builds will be. By Kyle Galbraith.
In this post, we will look at reducing the overall image size, to improve build time and reduce the amount of data transferred in each image. We will use a popular open-source project, dive, to help analyze a Docker image, stepping through each individual layer to see what files it adds to the image and how it impacts the total image size.
The article consists of the following parts:
diveinto a Docker image- Reducing image size
- Make use of .dockerignore
- Use smaller base images
- Leverage multi-stage builds
- Smaller images where possible
A multi-stage build allows you to specify multiple FROM statements in a single Dockerfile, and each of them represents a new stage in a build. You can also copy files from one stage to another. Files not copied from an earlier stage are discarded in the final image, resulting in a smaller image size. Nice one!
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