Escher-request NPM

escher-request

We wanted to make it easier to work with escher requests. This package provides an alternative to using packages like escher-suiteapi-js, escher-auth, escher-keypool and koa-escher-auth.

Setup

For escher-request to work, you should set ESCHER_INTEGRATIONS environment variable set with all your escher related config.

For compatibility reasons ESCHER_KEY_POOL and SUITE_ESCHER_KEY_POOL variables are also supported for storing config.

process.env.ESCHER_INTEGRATIONS = `[
  {
    "keyId": "test_test-sender_v1",
    "secret": "code"
  }
  {
    "keyId": "test_test-target_v1",
    "secret": "secret",
    "serviceUrl": "http://www.example.com:8080",
    "credentialScope": "eu/test-target/ems_request"
  }
]`;

For each service you want to communicate with include an object in the array with these params:

keyId sent with outgoing request, used during authentication to look up the matching secret
secret used to generate and validate the signature
serviceUrl (optional) base url of the service (needed for outgoing requests)
credentialScope (optional) will be set in auth header when sending a request towards the service (needed for outgoing requests)
acceptOnly (optional, default false) makes it easier to rotate your keys. When it's true it will only be used to validate incoming requests, and you can have a second entry for this service with the new secret, version two (..._v2) key id and acceptOnly as false which will be used for outgoing ones.

API

Making a request

Request API is intended to be as close to axios API as possible.

// Send a POST request
escherRequest.request({
  method: 'post',
  url: 'http://somewhere.com/user/12345',
  data: {
    firstName: 'Fred',
    lastName: 'Flintstone'
  }
})

The main difference is that only absolute url work, as the origin part of the url will be used to look up the escher keyId and secret set up in ESCHER_INTEGRATIONS for signing the request.

There is also an extra escherKeyId option, which lets you make calls with relative urls. In this case this keyId will be used to look up the serviceUrl of the target which will be prepended to the url.

escherRequest.get('/hello', { escherKeyId: 'test_test-target' })

Omit version information from the end of the key for this config (eg: key instead of key_v1)).

This allows you to write environment independent code more easily. You only have to change the value of the ESCHER_INTEGRATIONS environment variable between environments, and your requests will go to the correct destination signed with the correct credentials.

If you would like to use the package without ESCHER_INTEGRATIONS environment variable, you can explicitly pass in escherCredentialScope and escherSecret in config, which will be used to generate the authentication headers. For this special use case version information have to be included in the key, and only absolue url can be used.

escherRequest.get('http://localhost:45345/hello', {
  escherKeyId: 'test_test-target_v1',
  escherCredentialScope: 'eu/hap/ems_request',
  escherSecret: 'secret'
});

The plan is to support most of axios's config options. url, method, headers, data, params and paramsSerializer options are pre-processed, since they have direct impact on the escher signature to be generated. All other options are passed down to axios unchanged.

One noticeable difference from the default options of axios is the default value for timeout option. It is 25052 ms, while in axios it is 0 (no timeout).

Request method aliases

escherRequest.get(url, config)
escherRequest.delete(url, config)
escherRequest.head(url, config)
escherRequest.options(url, config)
escherRequest.post(url[, data, config])
escherRequest.put(url[, data, config])
escherRequest.patch(url[, data, config])

Pre-signing an URL

Pre-signs an url with given expiration (in second, by default it is 86400 secs, aka 24 hours). Mostly useful for ui handshake requests or integrating an iframe into a front-end.

escherRequest.preSignUrl(
  'http://www.example.com/etwas?a=4',
  { expires: 300 }
)

escherRequest.preSignUrl(
  '/etwas?a=4',
  { expires: 300, escherKeyId: 'test_test-target' }
)

Authenticate

When passed in the credentialScope of the service and parameters of a received request, returns whether it passes authentication or not (correct credentialScope, keyId, secret, etc is used).

const { authenticated, message } = escherRequest.authenticate(
  'eu/test-target/ems_request',
  {
    method: 'POST',
    url: '/puty',
    headers: {
      'content-type': 'application/json',
      host: 'localhost:9193',
      'x-ems-date': '20190616T183748Z',
      'x-ems-auth': 'EMS-HMAC-SHA256 Credential=test_test-target_v1 ...'
    },
    body: '{"duckling":4}'
  }
)

autheticated is boolean, shows whether it passed authentication or not, message contains a reason if it did not.

Usually you want to wrap this method in a middlaware that handles the specifics of your favorite framework.

See examples for ideas how this could be done: koa, koa-with-badyparser, express, express-with-bodyparser