Cocoapods binary cache

A plugin that helps to reduce the build time of Xcode projects which use Cocoapods by prebuilding pod frameworks and cache them in a remote repository to share across multiple machines.

Demo project and benchmark

To compare build time, we created a demo project with some popular pods added:

AFNetworking
SDWebImage
Alamofire
MBProgressHUD
Masonry
SwiftyJSON
SVProgressHUD
MJRefresh
CocoaLumberjack
Realm
SnapKit
Kingfisher

To try it:

$ cd PodBinaryCacheExample
$ sh BuildBenchMark.sh

And the results:

The result will vary depends on your machine and network condition. This is the spec of the machine we used to test the demo project:

MacBook Pro (15-inch, 2018)
Mac OS 10.14.6
Processor 2.6 GHz Intel Core i7
Memory 16 GB 2400 MHz DDR4

In our real project with around 15% of swift/ObjC code from vendor pods. After applied this technique and monitored on the CI system, we found that overall, it helped to reduce 10% of build time.

Installation

Install ruby 2.x version and python 3.x (which are usually available on most developers machine!).
To install the plugin, our preferred way is using Bundler. If you're not familiar with it, please take a look at Learn how to set it up here.
Just add a line to your Gemfile:

gem 'coccoapods-binary-cache', :path => 'https://github.com/grab/cocoapods-binary-cache.git', :tag => '0.0.3'

Then run:

$ bundle install

Usage

Cache config: At the same directory with your Podfile, add a json file and name it PodBinaryCacheConfig.json (the name is fixed) and content similar to this:

{
  "prebuilt_cache_repo": "<Link to your git repo which will store built frameworks>", // can be https or ssh.
  "cache_path": "~/Library/Caches/CocoaPods/<your_cache_dir>" // can be any directory, we recommend to cache frameworks to ~/Library/Caches/ then it's convenience to reuse across multiple projects.
}

On top of your Podfile add one line below to enable the plugin, it will hook to pod pre-install, post-install to do the build, cache stuffs:

plugin 'cocoapods-binary-cache'

Declare pods which need to be prebuilt by adding a flag :binary => true:

pod 'Alamofire', :binary => true

Run a pod command for the first time adding this plugin, and every time you add/upgrade a pod:

$ pod binary-cache --cmd=prebuild

It will build frameworks and push to the cache repo and also install prebuilt frameworks to your project. Then just open the Xcode project and build as normal.

Other members in your team don't need to build again, they just need to fetch prebuilt frameworks from cache and use the project as normal:

$ pod binary-cache --cmd=fetch
$ bundle exec pod install

Automate prebuild frameworks on CI

You can set up to run prebuild frameworks automatically on your CI. Eg. If your project is using gitlab CI, you just need to create a scheduled job (daily) which call the prebuild command:

// In .gitlab-ci.yml file
prebuild_pod:
  script:
    - $ pod binary-cache --cmd=prebuild
  only:
    variables:
      - $IS_PREBUILD_DEVPOD_JOB == "true"

How it works

Terms:

Cache-hit: a pod framework is prebuilt and has same version with the one in Pod lock file.
Cache-miss: a pod framework is not prebuilt or has different version with the on in Pod lock file.

1. Prebuild pod frameworks to binary and push to cache

With an added flag (:binary => true) to your pod in the Podfile, in the pod pre-install hook, It filters all pods which need to be built, then creates a separated Pod sandbox and generates a Pod.xcproject. We are using cocoapods-binary for this process.
Then it builds frameworks in the generated project above using cocoapods-rome. The products are frameworks and a Manifest file.
Compresses all built frameworks to zips and commit to the cache repo.

2. Fetch and use cached frameworks

It fetches built frameworks from cache repo and unzip them.
In pod pre-install hook, it reads Manifest.lock and Podfile.lock to compare prebuilt lib's version with the one in Podfile.lock, if they're matched -> add to the cache-hit dictionary, otherwise, add to the cache-miss dictionary. Then the plugin intercepts pod install-source flow and base on generated cache hit/miss dictionaries to decide using cached frameworks or source code.

Because we don't upgrade vendor pods every day, even once in a few months, the cache hit rate will likely be 100% most of the time.

Notes

Caching development pod will be supported in the future.
A git repo is used as the cache, but we can change to other storages such as S3, FTP server with some modifications to push/fetch cache task.

License

The cocoapods-binary-cache plugin is available as open-source under the terms of the MIT License. It uses cocoapods-rome and cocoapods-binary internally, which are also under MIT License.

lixiaoyu/cocoapods-binary-cache