How to speed up Gitlab CI job with cache and artifacts - rust

Question

I wish Gitlab test job for my project on Rust run faster.
Locally it rebuilds pretty fast, but in gitlab job, avery build runs slow as a first one.
Looking for a way to use artifacts or cache from previous pipline to speed up rust test and build processe.
# .gitlab-ci.yml
stages:
- test
test:
stage: test
image: rust:latest
script:
- cargo test

Answer 1

Gitlab CI/CD supports caching between CI jobs using the cache key in your .gitlab-ci.yml. It is only able to cache files in the project directory so you need to use the environment variable CARGO_HOME if you also want to cache the cargo registry.
You can add a cache setting at the top level to setup a cache for all jobs that don't have a cache setting themselves and you can add it below a job definition to setup a cache configuration for this kind of job.
See the keyword reference for all possible configuration options.
Here is one example configuration that caches the cargo registry and the temporary build files and configures the clippy job to only use the cache but not write to it:
stages:
- test
cache: &global_cache # Default cache configuration with YAML variable
# `global_cache` pointing to this block
key: ${CI_COMMIT_REF_SLUG} # Share cache between all jobs on one branch/tag
paths: # Paths to cache
- .cargo/bin
- .cargo/registry/index
- .cargo/registry/cache
- target/debug/deps
- target/debug/build
policy: pull-push # All jobs not setup otherwise pull from
# and push to the cache
variables:
CARGO_HOME: ${CI_PROJECT_DIR}/.cargo # Move cargo data into the project
# directory so it can be cached
# ...
test:
stage: test
image: rust:latest
script:
- cargo test
# only for demonstration, you can remove this block if not needed
clippy:
stage: test
image: rust:latest
script:
- cargo clippy # ...
only:
- master
needs: []
cache:
<<: *global_cache # Inherit the cache configuration `&global_cache`
policy: pull # But only pull from the cache, don't push changes to it
If you want to use cargo publish from CI, you should then add .cargo to your .gitignore file. Otherwise cargo publish will show an error that there is an uncommitted directory .cargo in your project directory.