travis-ci.com webhook authentication middleware.

See https://docs.travis-ci.com/user/notifications/#Configuring-webhook-notifications for more information about webhooks.

In brief:

• Configure travis-ci.com to send webhook notifications to your WAI-based web server (such as warp).
• Use the authenticate middleware to reject requests that don't originate from travis-ci.com.

For example,

-- In .travis.yml
notifications:
  webhooks: http://my-domain.com/my-webhook-path

-- In code
TravisCI.authenticate ["my-webhook-path"]

See the bottom of this module for a longer example.

{-# language OverloadedStrings #-}

import Network.Wai                    -- wai
import Network.Wai.Handler.Warp (run) -- warp
import Network.HTTP.Types             -- http-types

import qualified Network.Wai.Middleware.TravisCI as TravisCI

main :: IO ()
main =
  run 8000 (middleware app)

middleware :: Middleware
middleware =
  TravisCI.authenticate ["travis"]         -- (1)

app :: Application
app request respond =
  case pathInfo request of
    ["travis"] -> do                       -- (2)
      payload <- TravisCI.payload request  -- (3)
      print payload
    _ -> pure ()
  respond (responseLBS status200 [] "")

Above is a minimal WAI application that authenticates POSTs to /travis, then prints out the parsed payload (an aeson Value).

• At (1), we define the middleware, which authenticates every POST to /travis.
• At (2), we handle these POSTs in our application.
• At (3), we parse the JSON payload, whose schema is, unsurprisingly, barely defined at all. See https://docs.travis-ci.com/user/notifications/#Webhooks-Delivery-Format for more information.