CircleCI for iOS - caching cocoapods dependencies - ios

Question

I'm trying to run my iOS testsuite in CircleCI using fastlane scan. Running the tests is working great, but the total time is increased a lot by installing dependencies from cocoapods.
I've tried to cache the Pods directory by doing the following, however, the checksum is changing between the restore_cache step and the save_cache step:
- restore_cache:
key: 1-pods-{{ checksum "Podfile.lock" }}
- run:
name: Install Pods
command: pod install
- save_cache:
key: 1-pods-{{ checksum "Podfile.lock" }}
paths:
- ./Pods
Essentially, the pod install causes the checksum to change even if none of the pods have changed. As such, the key under which it's saved in cache never lines up with what's trying to be restored from cache.
Is there a better way to do this?

Answer 1

Yes, there is a way to make this work. restore_cache accepts key prefixes (https://circleci.com/docs/2.0/configuration-reference/#restore_cache). So to fall back to an earlier cache you can use something like this:
- restore_cache:
keys:
- 1-pods-{{ checksum "Podfile.lock" }}
- 1-pods-
There are some more specific guidelines here: https://circleci.com/docs/2.0/ios-migrating-from-1-2/#installing-cocoapods

Answer 2

These are the complete steps.
- restore_cache:
key: 1-pods-{{ checksum "Podfile.lock" }}
- run:
name: Install CocoaPods
command: |
if [ ! -d "Pods" ]
then
curl https://cocoapods-specs.circleci.com/fetch-cocoapods-repo-from-s3.sh | bash -s cf
bundle exec pod install
fi
- save_cache:
key: 1-pods-{{ checksum "Podfile.lock" }}
paths:
- ./Pods
First step is to restore cache.
Second step, if cache is not found, update the pods repo from circleci mirror and install pods. This step takes around 5 minutes so you better skip it if unnecessary.
Third step, save cache if key is still not occupied
source: https://medium.com/wandercodes/how-to-save-time-in-circleci-when-using-pods-4e00cd419ad8

Answer 3

OK, after running into this exact issue I solved it for myself. I'll leave solution here in case this ends up being the same for others.
What?
When trying to cache and restore cocoapod dependencies on circleci the checksum being used for my cache key is different at restore when compared to save; resulting in never finding a cache key match.
Why?
When circleci was adding my repo as a source it was including the .git extension to my repo. However, when I added the repo to my own machine (i.e., pod repo add <name> <url> I did not include the extension. So, on my local machine when I'd run pod install my Podfile.lock would list my private repo without the .git, which of course factors into the generation of the checksum. Then on circleci, it would go through the same process, but generate a Podfile.lock which did include the .git extension, in turn causing a different checksum, and ultimately a different cache key.
Solution
Remove the private repo from my local machine (i.e., pod repo remove <name>) and add it back again, being sure to include the .git extension as part of the url (i.e., pod repo add <name> https://my-vcs.com/path-to/repo.git).
One note regarding using the fallback method mentioned above. This actually resulted in a Sandbox out of sync error, because the old caches contained pods that were no longer aligned with the current state of the app. So I'd probably avoid using this technique.