Distributed environments frequently require the use of a reverse proxy. {project_name} offers several options to securely integrate with such environments.
== Configure the reverse proxy headers
{project_name} will parse the reverse proxy headers based on the `proxy-headers` option which accepts several values:
* By default if the option is not specified, no reverse proxy headers are parsed.
* `forwarded` enables parsing of the `Forwarded` header as per https://www.rfc-editor.org/rfc/rfc7239.html[RFC7239].
* `xforwarded` enables parsing of non-standard `X-Forwarded-*` headers, such as `X-Forwarded-For`, `X-Forwarded-Proto`, `X-Forwarded-Host`, and `X-Forwarded-Port`.
WARNING: If either `forwarded` or `xforwarded` is selected, make sure your reverse proxy properly sets and overwrites the `Forwarded` or `X-Forwarded-*` headers respectively. To set these headers, consult the documentation for your reverse proxy. Misconfiguration will leave {project_name} exposed to security vulnerabilities.
Take extra precautions to ensure that the client address is properly set by your reverse proxy via the `Forwarded` or `X-Forwarded-For` headers.
If this header is incorrectly configured, rogue clients can set this header and trick {project_name} into thinking the client is connected from a different IP address than the actual address. This precaution can be more critical if you do any deny or allow listing of IP addresses.
{project_name} assumes it is exposed through the reverse proxy under the same context path as {project_name} is configured for. By default {project_name} is exposed through the root (`/`), which means it expects to be exposed through the reverse proxy on `/` as well.
You can use a full URL for the `hostname` option in these cases, for example using `--hostname=https://my.keycloak.org/auth` if {project_name} is exposed through the reverse proxy on `/auth`.
For more details on exposing {project_name} on different hostname or context-path incl. Administration REST API and Console, see <@links.server id="hostname"/>.
Alternatively you can also change the context path of {project_name} itself to match the context path for the reverse proxy using the `http-relative-path` option, which will change the context-path of {project_name} itself to match the context path used by the reverse proxy.
Typical cluster deployment consists of the load balancer (reverse proxy) and 2 or more {project_name} servers on private network.
For performance purposes, it may be useful if load balancer forwards all requests related to particular browser session to the same {project_name} backend node.
The reason is, that {project_name} is using Infinispan distributed cache under the covers for save data related to current authentication session and user session.
The Infinispan distributed caches are configured with limited number of owners. That means that session related data are stored only in some cluster nodes and the other nodes need to lookup the data remotely if they want to access it.
For example if authentication session with ID 123 is saved in the Infinispan cache on node1, and then node2 needs to lookup this session, it needs to send the request to node1 over the network to return the particular session entity.
It is beneficial if particular session entity is always available locally, which can be done with the help of sticky sessions. The workflow in the cluster environment with the public frontend load balancer and two backend {project_name} nodes can be like this:
* This request is served by the frontend load balancer, which forwards it to some random node (eg. node1). Strictly said, the node doesn't need to be random, but can be chosen according to some other criteria (client IP address etc). It all depends on the implementation and configuration of underlying load balancer (reverse proxy).
* Infinispan distributed cache assigns the primary owner of the session based on the hash of session ID. See Infinispan documentation for more details around this. Let's assume that Infinispan assigned node2 to be the owner of this session.
From this point, it is beneficial if load balancer forwards all the next requests to the node2 as this is the node, who is owner of the authentication session with ID 123 and hence Infinispan can lookup this session locally. After authentication is finished, the authentication session is converted to user session, which will be also saved on node2 because it has same ID 123 .
The sticky session is not mandatory for the cluster setup, however it is good for performance for the reasons mentioned above. You need to configure your loadbalancer to sticky over the AUTH_SESSION_ID cookie. How exactly do this is dependent on your loadbalancer.
If your proxy supports session affinity without processing cookies from backend nodes, you should set the `spi-sticky-session-encoder-infinispan-should-attach-route` option
to `false` in order to avoid attaching the node to cookies and just rely on the reverse proxy capabilities.
To ensure that proxy headers are used only from proxies you trust, set the `proxy-trusted-addresses` option to a comma separated list of IP addresses (IPv4 or IPv6) or Classless Inter-Domain Routing (CIDR) notations.
When the proxy is configured as a TLS termination proxy the client certificate information can be forwarded to the server through specific HTTP request headers and then used to authenticate
clients. You are able to configure how the server is going to retrieve client certificate information depending on the proxy you are using.
The server supports some of the most commons TLS termination proxies such as:
The NGINX SSL/TLS module does not expose the client certificate chain. {project_name}'s NGINX certificate lookup provider rebuilds it by using the {project_name} truststore.
