Continuous Integration in Yaydoc using GitHub webhook API

In Yaydoc,  Travis is used for pushing the documentation for each and every commit. But this leads us to rely on a third party to push the documentation and also in long run it won’t allow us to implement new features, so we decided to do the continuous documentation pushing on our own. In order to build the documentation for each and every commit we have to know when the user is pushing code. This can be achieved by using GitHub webhook API. Basically we have to register our api to specific GitHub repository, and then GitHub will send a POST request to our API on each and every commit.

“auth/ci” handler is used to get access of the user. Here we request user to give access to Yaydoc such as accessing the public repositories , read organization details and write permission to write webhook to the repository and also I maintaining state by keeping the ci session as true so that I can know that this callback is for gh-pages deploy or ci deployOn

On callback I’m keeping the necessary informations like username, access_token, id and email in session. Then based on ci session state, I’m redirecting to the appropriate handler. In this case I’m redirecting to “ci/register”.After redirecting to the “ci/register”, I’m getting all the public repositories using GitHub API and then I’m asking the users to choose the repository on which users want to integrate Yaydoc CI

After redirecting to the “ci/register”, I’m getting all the public repositories using GitHub API and then I’m asking the users to choose the repository on which users want to integrate Yaydoc CI

router.post('/register', function (req, res, next) {
      request({
        url: `https://api.github.com/repos/${req.session.username}/${repositoryName}/hooks?access_token=${req.session.token}`,
        method: 'POST',
        json: {
          name: "web",
          active: true,
          events: [
            "push"
          ],
          config: {
            url: process.env.HOSTNAME + '/ci/webhook',
            content_type: "json"
          }
        }
      }, function(error, response, body) {
        repositoryModel.newRepository(req.body.repository,
          req.session.username,
          req.session.githubId,
          crypter.encrypt(req.session.token),
          req.session.email)
          .then(function(result) {
            res.render("index", {
              showMessage: true,
              messages: `Thanks for registering with Yaydoc.Hereafter Documentation will be pushed to the GitHub pages on each commit.`
            })
          })
      })
    }
  })

After user choose the repository, they will send a POST request to “ci/register” and then I’m registering the webhook to the repository and I’m saving the repository, user details in the database, so that it can be used when GitHub send request to push the documentation to the GitHub Pages.

router.post('/webhook', function(req, res, next) {
  var event = req.get('X-GitHub-Event')
  if (event == 'Push') {
      repositoryModel.findOneRepository(
        {
          githubId: req.body.repository.owner.id,
          name: req.body.repository.name
        }
      ).
      then(function(result) {
        var data = {
          email: result.email,
          gitUrl: req.body.repository.clone_url,
          docTheme: "",
        }
        generator.executeScript({}, data, function(err, generatedData) {
            deploy.deployPages({}, {
              email: result.email,
              gitURL: req.body.repository.clone_url,
              username: result.username,
              uniqueId: generatedData.uniqueId,
              encryptedToken: result.accessToken
            })
        })
      })
      res.json({
        status: true
      })
   }
})

After you register on webhook, GitHub will send a request to the url which we registered on the repository. In our case “https:/yaydoc.herokuapp.com/ci/auth” is the url. The type of the event can be known by reading ‘X-GitHub-Event’ header. Right now I’m registering only for the push event. So we’ll only be getting the push event. GitHub also gives us the repository details in the request body.

When the user makes a commit to the repository, GitHub will send a POST request to the Yaydoc’s server. Then, we’ll get the repository name and Github’s user ID from the request body. By use of this, I’ll retrieve the access token from the database which we already registered while the user registers the repository to the CI. The documentation will be generated using generate script and pushed to GitHub pages using deploy script.

Now Yaydoc generates documentation on every push when the user commits to the repository and also it will enable us to integrate new features in our own custom environment. We also plan to build a full featured CI platform.

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