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🎁 cargo plugin for quickly fetching dependencies πŸ¦€
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Jake-Shadle Refactor to use Backend trait (#11)
Also fixes up s3 url parsing and some other bugs 
in the s3 impl (as far as I can tell without testing)
Latest commit dd0bfbc Oct 28, 2019

🎁 cargo-fetcher

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Alternative to cargo fetch for use in CI or other "clean" environments that you want to quickly bootstrap with the necessary crates to compile/test etc your project(s).


  • You run CI jobs inside of GCP and you want faster and git downloads so that your compute resources can be spent on the things that you actually care about.

Why not?

  • You don't run CI inside of GCP. Currently cargo-fetcher only supports storing crates/git snapshots inside of GCS which means they can be located closer to the compute resources your CI is running on. PRs are of course welcome for adding additional storage backends though!
  • cargo-fetcher should not be used in a typical user environment as it completely disregards various safety mechanisms that are built into cargo, such as file-based locking.
  • You project doesn't have a Cargo.lock file. cargo-fetcher only works with Cargo.lock files (due to how cargo fetch works), so library crates without checked in lock files won't be able to use cargo-fetcher.



The gcs feature enables the use of Google Cloud Storage as a backend.

  • Must provide a url to the -u | --url parameter with the gsutil syntax gs://<bucket_name>(/<prefix>)?
  • Must provide GCP service account credentials either with --credentials or via the GOOGLE_APPLICATION_CREDENTIALS environment variable


The s3 feature enables the use of Amazon S3 as a backend.

  • Must provide a url to the -u | --url parameter, it must of the form http(s)?://<bucket>.s3(-<region>).<host>(/<prefix>)?
  • Must provide AWS credentials by the default mechanism(s) described here


This is an example from our CI for an internal project.


  • 424 crates: cached - 38MB, unpacked - 214MB
  • 13 crates source from 10 git repositories: db - 27MB, checked out - 38MB


The following CI jobs are run in parallel, each in a Kubernetes Job running on GKE. The container base is roughly the same as the official rust:1.36.0-slim image.

  • Build modules for WASM
  • Build modules for native
  • Build host client for native

~ wait for all jobs to finish ~

  • Run the tests for both the WASM and native modules from the host client


All 3 build jobs take around 1m2s each to do cargo fetch --target x86_64-unknown-linux-gnu


All 3 build jobs take 2-3s each to do cargo fetcher --include-index mirror followed by 6s to do cargo fetch --target x86_64-unknown-linux-gnu. The 6s can probably be further reduced.


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