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How does the Docker build cache work and when not to use it?

How does the Docker build cache work and when not to use it?

$ docker build -t print -date-time –no-cache. The no-cache argument will completely discard the cache, always executing all steps of the Dockerfile. The FROM instruction is the only line that is not affected by the no-cache argument. If the base image is present in the machine, it won’t be pulled again.

Which is the best way to build images in Docker?

This document covers recommended best practices and methods for building efficient images. Docker builds images automatically by reading the instructions from a Dockerfile — a text file that contains all commands, in order, needed to build a given image.

Is there a way to break up long lines in Docker?

There’s no magic or special things happening here. Using a backslash is the standard way to break up long lines into multiple lines on Unix-like operating systems. Since most Docker images are built using some form of Linux base image, then the backslash strategy works here as well.

Where does the dockerfile go when issuing a command?

When you issue a docker build command, the current working directory is called the build context. By default, the Dockerfile is assumed to be located here, but you can specify a different location with the file flag ( -f ).

How to create a docker image for a node?

To list images, simply run the images command. You should see at least two images listed. One for the base image node:12.18.1 and the other for our image we just build node-docker:latest. An image name is made up of slash-separated name components. Name components may contain lowercase letters, digits and separators.

Why is Docker not using cache for Gemfile?

Aside node : It is working perfectly on my local machine. Looking at the Docker documentation Leverage build cache doesn’t seem to explain the behaviour here as nor the Dockerfile, nor the Gemfile have changed, so the cache should be used. What could make Docker not using the cache for the Gemfile?

When to run NPM install in Docker build?

When dockerizing it (docker build .) the longest phase is the RUN npm install. The RUN npm install instruction runes on every small server code change, impacting the productivity by making the developer wait for the build to finish each time.