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How to build BitBucket Cloud add-on in Rails → accessing BitBucket API from the server

06 Jun 2016

The last thing I want to mention is how to make a call to BitBucket REST API from the server. This is something I struggled for. Seems the official documentation hasn't been updated and you need to figure it out on your own.

This article is Part 7 in a 7-Part Series.

Enable this plugin for your BitBucket Cloud account!

As the user already allowed the plugin to access his account it doesn't make sense to do an additional OAuth dance. So BitBucket Cloud OAuth supports a special JWT Grant that you can use from the add-on to get the access token.

Here's how I get the access token:

def get_access_token
  unless current_jwt_auth
    raise 'Missing Authentication context'
  end

  # Expiry for the JWT token is 3 minutes from now
  issued_at = Time.now.utc.to_i
  expires_at = issued_at + 180

  jwt = JWT.encode({
                       iat: issued_at,
                       exp: expires_at,
                       iss: current_jwt_auth.addon_key,
                       sub: current_jwt_auth.client_key
                   }, current_jwt_auth.shared_secret)

  response = HTTParty.post("#{current_jwt_auth.base_url}/site/oauth2/access_token", {
      body: {grant_type: 'urn:bitbucket:oauth2:jwt'},
      headers: {
          'Content-Type' => 'application/x-www-form-urlencoded',
          'Authorization' => 'JWT ' + jwt
      }
  })

  if response.code == 200
    Response.new(200, response.parsed_response)
  else
    Response.new(response.code)
  end
end

You don't need qsh here. You need to use application/x-www-form-urlencoded, JSON is not allowed.

The returned token will not have a refresh token, to refresh it call get_access_token again with JWT token.

Once you get the access token you can call BitBucket REST API with Authorization: Bearer token as you would normally do with any OAuth 2.0 service.

I hope you enjoyed the tutorial. If you have any questions feel free to contact me.

Get the source code