Generating rustdoc for github pages (Drone OS)

Written on May 17, 2020

Tags: DroneOS (1) Rust (1)

I’ve been playing with DroneOS and created a crate with some utility functions for the STM32F4xx series of processors. Unfortunately, the way that Drone OS builds, you can’t call cargo doc directly. It needs to be invoked from the drone program, which means that I couldn’t take advantage of

This blog post describes what I needed to do to get a second github pages site setup and have travis generate the documentation for me.

This blog ( is currently hosted as a github pages repository.

My crate is found in this repository.

Step 1 - Goto your domain name service provider and add a CNAME DNS entry which redirects to Now I have both and both redirecting to

I put this as the first step since it takes a few minutes for this to filter through through the DNS servers.

Step 2 - Generate a github acces token here. Make sure you record the token before closing the window, since you won’t be able to retrieve/view it once the window is closed.

Step 3 - Activate your repository on travis.

Step 4 - Goto your travis repository (mine was and click on More Options -> Settings (or add settings to your repository URL). Add an environment variable called GITHIB_TOKEN and paste in the value from Step 2 in. I also set “Only available on the master branch” and made sure “Display Value in build log” is NOT set.

Step 5 - Create your .travis.yml file. Mine looks like this:

language: rust
- stable
cache: cargo
- cargo +stable install just
- cat rust-toolchain
- rustup install $(cat rust-toolchain)
- rustup toolchain install $(cat rust-toolchain) -c rust-src -c llvm-tools-preview -t thumbv7em-none-eabihf
- cargo +$(cat rust-toolchain) install drone
- just doc
- echo > target/thumbv7em-none-eabihf/doc/CNAME
- cp index.html target/thumbv7em-none-eabihf/doc
  local_dir: target/thumbv7em-none-eabihf/doc
  provider: pages
  skip_cleanup: true
  github_token: "$GITHUB_TOKEN"
  keep_history: true
    branch: master

The before_install: section installs just using the stable version of the rust toolchain. Then it installs the appropriate nightly toolchain and the required dependencies needs for cargo doc to work. Finally it installs the drone CLI tool.

The script: uses the just doc command to build the actual documentation. The generated documnetation (for the STM32F4xx) winds up in the target tree: target/thumbv7em-none-eabihf/doc. This directory tree will wind up getting checked into the gh-pages branch of your repository. We need to create a text file called CNAME which matches the CNAME entry that was created in Step 1. cargo doc crates the crate documentation in a directory with the name from your Cargo.toml file, but with dashes replaced by underscores. I generated a redirection HTML file using this online generator. This way when the user browses your custom URL ( then it will redirect the user into the appropriate subdirectory.

The deploy: section tells travis to put the generated HTML files into the gh-pages branch of your repository (this is where the token generated in step 2 is used).

Step 6 - Verify that GitHub Pages is setup. Goto the Settings for your github repository and scroll down to the github pages section. Ensure that the pages is set to use the gh-pages branch, and that the Custom domain is filled in.

Step 7 - Push your changes to github (adding the .travis.yml and the generated index.html file). This should trigger travis to build the documentation.

If you can ping your custom URL ( and get back an IP address then you know that the DNS changes have been propogated. You should then be able to browse to that URL and see your generated documentation.