With the demise of Openshift Online and its free tier, I was looking for somewhere else to host my blog. Even though it's a Jekyll blog, it does some image resizing, so I can't use Github's native builder. I should be able to use Travis CI though, then push them to another Github repository for Pages hosting.

The Travis instructions for Github Pages instructions suggest you use Github personal access tokens for authentication, but that seems to give write access to all of my Github repositories - which I don't want to do.

You will need the command line client installed and logged in.

  1. Generate a key pair for Travis to use when pushing

     ssh-keygen -t rsa -b 4096 -f travis-key

    Don't commit the generated files!

  2. Create a repository on Github for the generated site to be pushed to. In that repository, go to Settings, Deploy keys, then Add deploy key. Copy in travis-key.pub which you generated in the previous step, check "Enable write access", then add the key.

  3. The private key should be encrypted. From the blog repository:

     travis encrypt-file -r 33d/blog travis-key

    where travis-key is one of the files created earlier by ssh-keygen.

    This command will suggest you add a line to your before_install section - do that.

  4. Put at the end of .travis.yml's before_install, to stop ssh-add complaining about the key's permissions:

     - chmod 400 ../travis-key
  5. Add this to .travis.yml, to perform the Git push:

     - eval "$(ssh-agent -s)"
     - ssh-add ../travis-key
     - git clone git@github.com:33d/blog-pages.git target
     - cp -pr _site/* target
     - git -C target checkout -b gh-pages
     - git -C target add .
     - git -C target commit -m "$( date --utc --iso-8601=seconds )"
     - git -C target push --force origin gh-pages

    I use a different repository for this, because I don't want the build artifacts clogging the blog repository.

You can see my completed .travis.yml file.