This directory includes scripts and tools for setting up Flutter's continuous integration environments. ## Cirrus Linux Flutter's Linux tasks run on a custom Docker image. The `Dockerfile` for this image can be found at [/dev/ci/docker_linux/Dockerfile](https://github.com/flutter/flutter/blob/master/dev/ci/docker_linux/Dockerfile). On each new change to this `Dockerfile`, Cirrus will build a new version of the Docker image as a dependency to any Linux tests. It is no longer necessary to manually build and push the Docker image locally. There are some factors external to the actual `Dockerfile` that would necessitate rebuilding the Docker image, such as upstream code changes, (Linux distribution) repository updates or a file that gets `COPY`ied into the image changing. In this case, a trivial `Dockerfile` change (such as a comment) would invalidate the cache and trigger a rebuild.