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Configuration and activation

Railgun is configured in /etc/railgun/railgun.conf (GNU/Linux). The most important directives are wan.port, which specifies the port Railgun listens on, memcached.servers, a space separated list of host:port memcached instances for Railgun to utilize. It is also possible to specify the full path to a single socket file for memcached. Using a socket file is recommended for best performance if your memcached does not require network communication. Make sure at least one memcached instance is defined. Full details on the available options can be found in the Railgul Execution docs.

If you will be using Railgun in combination with a website hosted behind the same NAT scheme, then you will also need to configure static IP mapping. In other words, if your website and Railgun node are running behind the same router or firewall, there are extra configuration steps necessary to properly route requests. More details in the Potential problems and common issues section. Contact support for assistance, or you can use the examples in /etc/railgun/railgun-nat.conf to define one yourself.

Railgun requires an activation step before usage. To activate, you will need to update the configuration file with the external IP address or a hostname which resolves to the external IP of your Railgun instance for activation.public_ip and your activation token for activation.token. You can determine the external IP address of a server with the following command:

$ curl

By default, Railgun will listen on all interfaces. It is best practice to specify the interface you would like Railgun to use. You can do that by setting the wan.ip option to the IP address of the interface you would like Railgun to listen on. This is especially important if you have a local link IPv6 address, as Railgun will prefer that to an IPv4 address and may not work as a result.

Business and Enterprise users can find the Railgun activation token listed on the Account Settings page. Details on this page can be found in the Administration documentation. Optimized Partners must use the init API method to acquire an activation token (rtkn). Business and Enterprise users should add a Railgun on the listing page, if you haven’t already. It can be named anything you like. After adding a Railgun, the token will be listed on the page and you can toggle the Railgun to ‘On.’ The token is a 32 character hash of numbers and letters. Copy this hash into the activation.token option in your Railgun configuration file. If your public IP and activation token are properly configured, the first time you start Railgun it will register and download a newly generated SSL certificate to encrypt traffic. To make sure that activation works properly, check your logs for a successful activation response when starting Railgun:

$  tail -f /var/log/messagesOct 27 22:29:41 www rg-listener: [Activation] Activation POST completed.Oct 27 22:29:41 www rg-listener: [Activation] Assigned Railgun ID: 1Oct 27 22:29:41 www rg-listener: [Activation] Acquired cert from server

If there is a certificate error in the system log or during startup, ensure that the necessary certificate bundle is installed as described in Preparing the Environment so that Railgun may connect securely back to Cloudflare’s activation servers.

As an example, we are going to use domain The newly generated certificate is signed against the domain and our system will automatically set your new subdomain to resolve to the IP specified by activation.public_ip. You can use this hostname to test Railgun without enabling the service for all users. More details are in the Testing Railgun section below.

Starting the service

You should start the service in the manner that your operating system recommends. This is likely either by using the init script directly, or by invoking the service command:

(GNU/Linux)$ /etc/init.d/railgun startStarting railgun:                                          [  OK  ]
$ service railgun startStarting railgun:                                          [  OK  ]

After running the init script, there should be an rg-listener process listening on the configured port (2408 by default). You can use netstat to make sure:

(GNU/Linux)$ netstat -plnt | grep 2408tcp        0      0 :::2408                     :::*                        LISTEN      2981/rg-listener

Provided that your port is open to Cloudflare traffic, it’s time for testing. If you don’t see the process running, then there may be an issue with activation or your configuration. The Railgun panic log, which is written to /var/log/railgun/panic.log by default, may contain more information. You can also attempt to start Railgun without the init script to see if any errors are present at start:

(GNU/Linux)$ sudo -u railgun /usr/bin/rg-listener -config=/etc/railgun/railgun.conf

Testing Railgun

Once you have configured Railgun, you can test its operation using the Test button on the Cloudflare dashboard found in Speed > Optimization > scroll down to Railgun > Test. This will indicate whether a request to your web server uses Railgun.

The log file can also be used to monitor results. By default, we log only errors. For testing, you need to raise the log.level option from 0 to 5 in your Railgun configuration and then restart the service. You can then tail the logs to watch the requests being processed:

$  tail -f /var/log/messagesOct 27 23:35:57 www railgun[]: Handling new WAN connectionOct 27 23:35:57 www railgun[]: Rx [0000000000... FnPing 2012-10-27 23:37:55.872617 +0000 UTC]Oct 27 23:35:57 www railgun[]: Tx [0000000000... FnPong 2012-10-27 23:37:55.872617 +0000 UTC]Oct 27 23:35:57 www railgun[]: Transmit time: 550usOct 27 23:36:06 www railgun[]: Rx [ab18927f79... FnBegin ab18927f79... FnRequest HEAD HTTP/1.1  ab18927f79... FnData DENone 374   ab18927f79... FnPush]Oct 27 23:36:06 www railgun[]: ab18927f79... waiting for requestOct 27 23:36:06 www railgun[]: ab18927f79... HEAD HTTP/1.1 []Oct 27 23:36:06 www railgun[]: ab18927f79... Starting connection to LANOct 27 23:36:06 www railgun[]: ab18927f79... connected to 27 23:36:06 www railgun[]: ab18927f79... Request sent to serverOct 27 23:36:06 www railgun[]: ab18927f79... waiting for responseOct 27 23:36:06 www railgun[]: ab18927f79... Response is readyOct 27 23:36:06 www railgun[]: ab18927f79... Received responseOct 27 23:36:06 www railgun[]: ab18927f79... Forcing wantedDeltaOct 27 23:36:06 www railgun[]: ab18927f79... HTTP/1.1 301 Moved PermanentlyOct 27 23:36:06 www railgun[]: Tx [ab18927f79... FnData DENone 328  ]Oct 27 23:36:06 www railgun[]: ab18927f79... completed (0 body bytes in 0.001572 seconds/0)#012Oct 27 23:36:06 www railgun[]: ab18927f79... waiting for requestOct 27 23:36:06 www railgun[]: Transmit time: 88usOct 27 23:36:06 www railgun[]: Tx [ab18927f79... FnPush]Oct 27 23:36:06 www railgun[]: Transmit time: 48us

Railgun will produce 5xx messages when the rg-listener service is unable to reach the origin web server. Checking that the route between the Railgun server and the web server is clear is essential before contacting support. The easiest way of checking that is by performing a curl command from the Railgun server to the origin web server. If Railgun and the web server are both run on the same physical server, check that it allows loopback HTTP connections on ports 80 and 443 in its firewall settings. Please ensure the correct port is open and contact support if errors persist.

Going live

It is recommended that you consult the Testing Railgun section before enabling Railgun for all visitors to your site.

When you wish to go live, Enterprise and Business users should select the desired Railgun for your domain on the Cloudflare Settings page from the drop-down and then toggle the switch to ‘On’. Optimized Partners should use the conn_set with mode set to 0 or conn_setmode_enabled method to enable Railgun. Railgun may take up to five minutes to fully activate, after which you should see the CF-Railgun HTTP header present in responses from all your active Cloudflare DNS records.