by Jordan Kasper So, you’ve probably used it before: key authentication. The basic idea is simple, to authenticate your app or client with a given service you send a key to identify (and authorize) yourself. Also, this is not intended for individual users necessarily, but rather for systems talking to each other. (Just to be clear, for users authenticating themselves you might want to look into OAuth2, something Express Gateway also offers.) In this article I’ll be showing you how to get up and running with key authentication quickly and easily with Express Gateway (EG). We’ll talk about setting up and configuring your gateway, creating credentials, and sending authenticated requests. This is a brief introduction, so be sure to read the documentation and test things before you deploy your API gateway! Creating and Configuring the Gateway Your first step might be to generate a new Express Gateway instance. (Feel free to skip this step if you’ve already done this.) You’ll want to first install the package and then generate a new gateway: express-gateway ~$ npm i -g express-gateway

~$ eg gateway create ? What's the name of your Express Gateway? widget-factory ? Where would you like to install your Express Gateway? widget-factory ? What type of Express Gateway do you want to create? Getting Started with Express Gateway created package.json created server.js

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To start widget-factory, run the following commands: cd widget-factory &amp;&amp; npm start Great! Before we start up our gateway for the first time, let’s go ahead and configure it. Gateway Configuration Express Gateway has two primary configuration files (plus model configuration) in the directory of your new project: the file and the file. The system config file is where you will set up things like database access (for the gateway, not your individual microservices) and certain security settings for things like OAuth2. We won’t be working in that file today (which also means our for this example). /config gateway.config.yml system.config.yml users and credentials will not be saved The gateway configuration file is where you configure HTTP, endpoints, policies (like key authentication), and pipelines (which are just a series of policies applied to some endpoints). The default generated config file creates one API endpoint for the gateway at and proxies those requests to – you’ll want to change that later, but we’ll leave it for now. What we need to do is add a policy to the “api-basic” pipeline (the only one in there). /ip https://httpbin.org/ip Find your “pipelines” block in the file and make it look like this: gateway.config.yml pipelines: - name: api-basic apiEndpoints: - api policies: - key-auth: ## This line is new!! - proxy: - action: serviceEndpoint: httpbin changeOrigin: true Notice that we added our “key-auth” policy the “proxy” policy. The policies in each pipeline are , so be sure to put them in the order you want them to execute. In our case, we should proxy the API request if the authentication fails. before ordered not Believe it or not, that’s the change you need to make to our demo gateway to enable key authentication! You can test this out by starting up the gateway and making a simple request to (or any other endpoint really): only GET /ip ~/widget-factory$ npm start You can test the HTTP request using cURL, or a tool like (which I highly recommend for API development). Here is the response you might get using cURL: Postman ~$ curl -D - "http://localhost:8080/ip" HTTP/1.1 401 Unauthorized X-Powered-By: Express Content-Type: text/html; charset=utf-8 Content-Length: 9 ETag: W/"9-PatfYBLj4Um1qTm5zrukoLhNyPU" Date: Sun, 16 Jul 2017 19:37:52 GMT Connection: keep-alive

Forbidden Notice that our response code was because we did send an API key. We’ll talk more about these status codes later, but for now let’s make an API key. 401 not Generating Key Credentials Our first step to create an API key is to create a “user” in the system. Open up another terminal window and navigate to your gateway project directory. Now we can use the same command we used to generate the gateway to create credentials: eg ~/widget-factory$ eg users create ? Enter username [required]: jordan ? Enter firstname [required]: Jordan ? Enter lastname [required]: Kasper ? Enter email: jordan@widgets-r-us.com ? Enter redirectUri: ✔ Created jordan I’ve left the blank here because we are not using it in key authentication, but you might need for other schemes. Now that we have a user, can either create an “app” for that user and then “credentials”, or we can just create the “credentials” for the user themselves. I’ll do the second option for now: redirectUri ~/widget-factory$ eg credentials create -c jordan -t key-auth ✔ Created { "isActive": true, "createdAt": "Sun Jul 16 2017 15:48:48 GMT-0400 (EDT)", "updatedAt": "Sun Jul 16 2017 15:48:48 GMT-0400 (EDT)", "keyId": "0J6961Lhn8JgxYybTXFdRg", "keySecret": "23BfI6QVqgdxP3ty8F4Jx3", "scopes": null, "consumerId": "jordan" } That’s it! Notice that the output above shows us out and . These two pieces together create our final API key for the system. "keyId" "keySecret" Sending Authenticated Requests Now that we have some credentials we can send some more requests to our API (through our gateway). ~$ curl -H "Authorization: apiKey 0J6961Lhn8JgxYybTXFdRg:23BfI6QVqgdxP3ty8F4Jx3" -I "http://localhost:8080/ip" HTTP/1.1 200 OK x-powered-by: Flask connection: close server: meinheld/0.6.1 date: Sun, 16 Jul 2017 19:54:49 GMT content-type: text/html; charset=utf-8 content-length: 12793 access-control-allow-origin: * access-control-allow-credentials: true x-processed-time: 0.00561594963074 via: 1.1 vegur There are two points of note above: first, we got a response! That’s great, that means our auth check passed! So how did we do that? We sent the header with our key in it. Remember, our key is made up of two parts. So you can see above that the header value is actually two pieces of information separated by a colon (“:”). Additionally, we prefix that value with our header scheme: “apiKey”. 200 Authorization Authorization Authorization: apiKey 0J6961Lhn8JgxYybTXFdRg:23BfI6QVqgdxP3ty8F4Jx3

header name : scheme keyId : keySecret Status Codes As you see above, we got a response status code, meaning success! That status code actually came from our API service (in this case httpbin.org) from our gateway. If you request a resource that doesn’t exist on that service you should receive a , for example. The gateway will send back a when the key is not authenticated – or missing entirely. But it could also send back a if the user is authenticated, but not authorized for the given resource. This could happen if you are using “scopes”. 200 not 404 401 403 What’s a Scope? We won’t get deep into scopes in this blog post, but the scopes are the main entities for specifying authorizations within Express Gateway. A scope is simply a pre-defined string added to your gateway configuration (both on an API endpoint and then again on a policy in a pipeline for that endpoint). API endpoints are secured by specifying scopes. To be authorized for an API endpoint that is secured by a scope, a consumer must have a credential containing the scope listed on the API endpoint. In other words, the scopes on the endpoint have to match the scopes on the user’s (or app’s) key credentials. Additional Configuration There are more options you can add to your gateway “key-auth” policy to secure it further or simply customize it. For example, by default the gateway will accept keys in both the headers and query string as well. You can easily disable this with the option: disableQueryParam pipelines: - name: api-basic apiEndpoints: - api policies: - key-auth: - disableQueryParam: true ## Disable API keys in the query string - proxy: - action: serviceEndpoint: httpbin changeOrigin: true You can also change the header used for authentication (although this would break with current standards) or the scheme used: pipelines: - name: api-basic apiEndpoints: - api policies: - key-auth: - apiKeyHeader: "X-My-Auth-Header" - apiKeyHeaderScheme: "key-pair" - proxy: - action: serviceEndpoint: httpbin changeOrigin: true If you used the configuration above you would need to modify the header you send in all authenticated API requests like so: ~$ curl -H "X-My-Auth-Header: key-pair 0J6961Lhn8JgxYybTXFdRg:23BfI6QVqgdxP3ty8F4Jx3" -I "http://localhost:8080/ip" Managing Key Credentials Our last topic for this post has to do with managing those keys you’ve generated. You will probably find a time when you need to deactivate a user’s access. This is easily accomplished on the command line by deactivating their credentials: ~$ eg credentials deactivate -t key-auth 0J6961Lhn8JgxYybTXFdRg ✔ Deactivated 0J6961Lhn8JgxYybTXFdRg After performing this action, the given will no longer be authenticated in the gateway. This is a permanent action, and the credentials can easily be reactivated with the companion sub command: keyId not activate ~$ eg credentials activate -t key-auth 0J6961Lhn8JgxYybTXFdRg ✔ Activated 0J6961Lhn8JgxYybTXFdRg Wrapping Up One of the biggest things an API gateway can do for you is centralize the authentication for your various microservices. And Express Gateway makes this process extremely straight forward. Take a look at the and give it a try! documentation Check out the to become a contributor or maintainer to this new open source API gateway built entirely on Express.js. Express Gateway

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