How to clear docker cache and possible DevOps issue related to docker

Dmytro Tus

Full Stack Web developer

DevOps teams often encounter issues related to Continuous Deployment (CD) and Continuous Integration (CI) in various Git applications, such as GitLab, GitHub, or Bitbucket.

Let’s examine some common examples.

Imagine you have CD/CI pipelines set up in GitLab. For running the worker, you typically use Docker on your local machine.

This means that with your local Docker environment and hardware, you are running an executor. In the case of GitLab, this is referred to as the GitLab Runner.

You use this setup primarily for the following tasks:

• Running tests
• Deployment scripts
• Build images

Occasionally, everything may appear to be working fine, but suddenly, you encounter an unexpected error:

Need to get 66.6 MB of archives.
After this operation, 254 MB of additional disk space will be used.
E: You don't have enough free space in /var/cache/apt/archives/.
Cleaning up project directory and file based variables
00:00
ERROR: Job failed: exit code 1

You may encounter this error in your GitLab pipeline.

This error indicates that there isn't enough space on your local machine, as it is being used to execute tasks.

Fixing the issue of Missing cache in Docker

First, you can check how much space your local Docker is currently using.

user@MacBookPro ~ % docker system df

TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          26        11        9.42GB    7.79GB (82%)
Containers      14        14        14.48MB   0B (0%)
Local Volumes   32        4         3.693GB   2.891GB (78%)
Build Cache     64        0         0B        0B

If you space is almost full you can run the commands

The simplest command but you need to be carefull with it

docker system prune

WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all dangling images
  - unused build cache

Are you sure you want to continue? [y/N] y

Deleted build cache objects:
....
f4ntwdma4mzvqiwo7322jj1u9
uz0xfj9170zhhucp6aq1ikgue

Total reclaimed space: 32.52GB

Another command when we will delete only build cache:

docker builder prune

WARNING! This will remove all dangling build cache. Are you sure you want to continue? [y/N] y
Total:	0B

After clear the docker cache you gitlab runner will work as expected ✅

Happy coding 🥳