@unleash/proxy

The Unleash Proxy (Open-Source)

Usage no npm install needed!

<script type="module">
  import unleashProxy from 'https://cdn.skypack.dev/@unleash/proxy';
</script>

README

Build & Tests npm Docker Pulls

The Unleash Proxy

The Unleash Proxy simplifies integration with frontend & native applications running in the context of a specific user. The Unleash proxy sits between the proxy SDK and the Unleash API and ensures that you internal feature toggle configuration is not exposed to the world.

The proxy offers:

  • High performance - a single proxy instance can handle thousands req/s, and can be horizontally scaled.
  • Privacy for end-users - Your end users are not exposed to the unleash API and can be hosted by you This ensures no user data (userId, IPs, etc) is shared.
  • Secure - It is controlled by you, and can hosted on your domain. In addition no feature toggle configuration is shared with the user, only evaluated toggles.

You can read more about the proxy in our documentation

Run The Unleash Proxy

The Unleash proxy is a small stateless HTTP application you run. The only requirement is that it needs to be able to talk with the Unleash API (either Unleash OSS or Unleash Hosted).

Run with Docker

The easies way to run Unleash is via Docker. We have published a docker image on docker hub.

Step 1: Pull

docker pull unleashorg/unleash-proxy

Step 2: Start

docker run \
   -e UNLEASH_PROXY_SECRETS=some-secret \
   -e UNLEASH_URL=https://app.unleash-hosted.com/demo/api/ \
   -e UNLEASH_API_TOKEN=56907a2fa53c1d16101d509a10b78e36190b0f918d9f122d \
   -p 3000:3000 \
   unleashorg/unleash-proxy

You should see the following output:

Unleash-proxy is listening on port 3000!

Step 3: verify

In order to verify the proxy you can use curl and see that you get a few evaluated feature toggles back:

curl http://localhost:3000/proxy -H "Authorization: some-secret"  

Expected output would be something like:

{
    "toggles": [{
        "name": "demo",
        "enabled": true,
        "variant": {
            "name": "disabled",
            "enabled": false
        }
    }, {
        "name": "demoApp.step1",
        "enabled": true,
        "variant": {
            "name": "disabled",
            "enabled": false
        }
    }]
}

Health endpoint

The proxy will try to synchronize with the Unleash API at startup, until it has successfully done that the proxy will return HTTP 503 - Not Read? for all request. You can use the health endpoint to validate that the proxy is ready to recieve requests:

curl http://localhost:3000/proxy/health -I
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Access-Control-Expose-Headers: ETag
Content-Type: text/html; charset=utf-8
Content-Length: 2
ETag: W/"2-eoX0dku9ba8cNUXvu/DyeabcC+s"
Date: Fri, 04 Jun 2021 10:38:27 GMT
Connection: keep-alive
Keep-Alive: timeout=5

Available options

Option Environment Variable Default value Required Description
unleashUrl UNLEASH_URL n/a yes API Url to the Unleash instance to connect to
unleashApiToken UNLEASH_API_TOKEN n/a yes API token (client) needed to connect to Unleash API.
clientKeys UNLEASH_PROXY_CLIENT_KEYS n/a yes List of client keys that the proxy should accept. When querying the proxy, Proxy SDKs must set the request's client keys header to one of these values. The default client keys header is Authorization.
proxySecrets UNLEASH_PROXY_SECRETS n/a no Deprecated alias for clientKeys. Please use clientKeys instead.
proxyPort PORT 3000 no The port where the proxy should listen.
proxyBasePath PROXY_BASE_PATH "" no The base path to run the proxy from. "/proxy" will be added at the end. For instance, if proxyBasePath is "base/path", the proxy will run at /base/path/proxy.
unleashAppName UNLEASH_APP_NAME "unleash-proxy" no App name to used when registering with Unleash
unleashInstanceId UNLEASH_INSTANCE_ID generated no Unleash instance id to used when registering with Unleash
refreshInterval UNLEASH_FETCH_INTERVAL 5000 no How often the proxy should query Unleash for updates, defined in ms.
metricsInterval UNLEASH_METRICS_INTERVAL 30000 no How often the proxy should send usage metrics back to Unleash, defined in ms.
environment UNLEASH_ENVIRONMENT undefined no If set this will be the environment used by the proxy in the Unleash Context. It will not be possible for proxy SDKs to override the environment if set.
projectName UNLEASH_PROJECT_NAME undefined no The projectName (id) to fetch feature toggles for. The proxy will only return know about feature toggles that belongs to the project, if specified.
logger n/a SimpleLogger no Register a custom logger.
logLevel LOG_LEVEL "warn" no Used to set logLevel. Supported options: "debug", "info", "warn", "error" and "fatal"
customStrategies UNLEASH_CUSTOM_STRATEGIES_FILE [] no Use this option to inject implementation of custom activation strategies. If you are using UNLEASH_CUSTOM_STRATEGIES_FILE you need to provide a valid path to a javascript files which exports an array of custom activation strategies and the SDK will automatically load these
trustProxy TRUST_PROXY false no By enabling the trustProxy option, Unleash Proxy will have knowledge that it's sitting behind a proxy and that the X-Forwarded-* header fields may be trusted, which otherwise may be easily spoofed. The proxy will automatically enrich the ip address in the Unleash Context. Can either be true/false (Trust all proxies), trust only given IP/CIDR (e.g. '127.0.0.1') as a string. May be a list of comma separated values (e.g. '127.0.0.1,192.168.1.1/24'
namePrefix UNLEASH_NAME_PREFIX undefined no Used to filter features by using prefix when requesting backend values.
tags UNLEASH_TAGS undefined no Used to filter features by using tags set for features. Format should be tagName:tagValue,tagName2:tagValue2
clientKeysHeaderName CLIENT_KEY_HEADER_NAME "authorization" no The name of the HTTP header to use for client keys. Incoming requests must set the value of this header to one of the Proxy's clientKeys to be authorized successfully.

Experimental options

Some functionality is under validation and introduced as experimental, to allow us to test new functionality early. You should expect these to change in any future feature release.

Option Environment Variable Default value Required Description
expBootstrap n/a n/a no Where the Proxy can bootstrap configuration from. See Node.js SDK for details.
expBootstrap.url EXP_BOOTSTRAP_URL n/a no Url where the Proxy can bootstrap configuration from. See Node.js SDK for details.
expBootstrap.urlHeaders.Authorization EXP_BOOTSTRAP_AUTHORIZATION n/a no Authorization header value to be used when bootstrapping
expServerSideSdkConfig.tokens EXP_SERVER_SIDE_SDK_CONFIG_TOKENS n/a no API tokens that can be used by Server SDKs (and proxies) to read feature toggle configuration from this Proxy instance.
### Run with Node.js:

STEP 1: Install dependency

 npm install @unleash/proxy

STEP 2: use in your code

const port = 3000;

const { createApp } = require('@unleash/proxy');


const app = createApp({
    unleashUrl: 'https://app.unleash-hosted.com/demo/api/',
    unleashApiToken: '56907a2fa53c1d16101d509a10b78e36190b0f918d9f122d',
    clientKeys: ['proxy-secret', 'another-proxy-secret', 's1'],
    refreshInterval: 1000,
    // logLevel: 'info',
    // projectName: 'order-team',
    // environment: 'development',
});

app.listen(port, () =>
    // eslint-disable-next-line no-console
    console.log(`Unleash Proxy listening on http://localhost:${port}/proxy`),
);

Proxy clients

To make the integration simple we have developed proxy client SDKs. You can find them all in our documentation: