Docker Layer Caching (DLC) is a great feature to use if building Docker images is a regular part of your CI/CD process. DLC will save image layers created within your jobs, rather than impact the actual container used to run your job.
There are some limitations to the availability of these cached layers. The DLC volumes are deleted after 3 days of not being used in a job. Additionally, CircleCI will create a maximum of 50 DLC volumes per project, so a maximum of 50 concurrent
machine or Remote Docker jobs per project can have access to DLC.
In-depth documentation for
docker_layer_caching can be found here: https://circleci.com/docs/2.0/docker-layer-caching/