Can Travis CI cache docker images? - caching

Question

Is it possible to add a setting to cache my docker image anywhere in the travis configuration ? Mine is a bigger docker image and it takes a while for it to download.
Any suggestions ?

Answer 1

Simplest solution today (October 2019) is to add the following to .travis.yml:
cache:
directories:
- docker_images
before_install:
- docker load -i docker_images/images.tar || true
before_cache:
- docker save -o docker_images/images.tar $(docker images -a -q)

Answer 2

See Caching Docker Images on Build #5358
for the answer(s). For Docker 1.12 available now on Travis, it is recommended to manually cache the images. For the Docker 1.13, you could use its --cache-from when it is on Travis.
Save:
before_cache:
# Save tagged docker images
- >
mkdir -p $HOME/docker && docker images -a --filter='dangling=false' --format '{{.Repository}}:{{.Tag}} {{.ID}}'
| xargs -n 2 -t sh -c 'test -e $HOME/docker/$1.tar.gz || docker save $0 | gzip -2 > $HOME/docker/$1.tar.gz'
Load:
before_install:
# Load cached docker images
- if [[ -d $HOME/docker ]]; then ls $HOME/docker/*.tar.gz | xargs -I {file} sh -c "zcat {file} | docker load"; fi
Also need to declare a cache folder:
cache:
bundler: true
directories:
- $HOME/docker

Answer 3

Docker images are not recommended to be cached regard to Travis document here
https://docs.travis-ci.com/user/caching/#things-not-to-cache

Answer 4

I just found the following approach as discussed in this article.
services:
- docker
before_script:
- docker pull myorg/myimage || true
script:
- docker build --pull --cache-from myorg/myimage --tag myorg/myimage .
- docker run myorg/myimage
after_script:
- docker images
before_deploy:
- echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
deploy:
provider: script
script: docker push myorg/myimage
on:
branch: master

Answer 5

This works for me:
Update the desired docker image name instead of <IMAGE_NAME_HERE> (3 places).
You can also use the same configuration for multiple images, docker save can handle multiple images, just make sure to pull them before trying to save them.
services:
- docker
cache:
directories:
- docker-cache
before_script:
- |
filename=docker-cache/saved_images.tar
if [[ -f "$filename" ]]; then docker load < "$filename"; fi
mkdir -p docker-cache
docker pull <IMAGE_NAME_HERE>
docker save -o "$filename" <IMAGE_NAME_HERE>
script:
- docker run <IMAGE_NAME_HERE>...