[[_providers]]

== Service Provider Interfaces (SPI)

{project_name} is designed to cover most use-cases without requiring custom code, but we also want it to be customizable.
To achieve this {project_name} has a number of Service Provider Interfaces (SPI) for which you can implement your own providers.

[[_implementing_spi]]
=== Implementing an SPI

To implement an SPI you need to implement its ProviderFactory and Provider interfaces. You also need to create a service configuration file.

For example, to implement the Theme Selector SPI you need to implement ThemeSelectorProviderFactory and ThemeSelectorProvider and also provide the file
`META-INF/services/org.keycloak.theme.ThemeSelectorProviderFactory`.

Example ThemeSelectorProviderFactory:

[source,java]
----
package org.acme.provider;

import ...

public class MyThemeSelectorProviderFactory implements ThemeSelectorProviderFactory {

    @Override
    public ThemeSelectorProvider create(KeycloakSession session) {
        return new MyThemeSelectorProvider(session);
    }

    @Override
    public void init(Config.Scope config) {
    }

    @Override
    public void postInit(KeycloakSessionFactory factory) {
    }

    @Override
    public void close() {
    }

    @Override
    public String getId() {
        return "myThemeSelector";
    }
}
----

It is recommended that your provider factory implementation returns unique id by method `getId()`. However
there can be some exceptions to this rule as mentioned below in the <<_override_builtin_providers,Overriding providers>> section.

NOTE: {project_name} creates a single instance of provider factories which makes it possible to store state for multiple requests.
Provider instances are created by calling create on the factory for each request so these should be light-weight object.

Example ThemeSelectorProvider:

[source,java]
----
package org.acme.provider;

import ...

public class MyThemeSelectorProvider implements ThemeSelectorProvider {

    public MyThemeSelectorProvider(KeycloakSession session) {
    }


    @Override
    public String getThemeName(Theme.Type type) {
        return "my-theme";
    }

    @Override
	public void close() {
    }
}
----

Example service configuration file (`META-INF/services/org.keycloak.theme.ThemeSelectorProviderFactory`):

[source]
----
org.acme.provider.MyThemeSelectorProviderFactory
----

To configure your provider, see the link:https://www.keycloak.org/server/configuration-provider[Configuring Providers] guide.

For example, to configure a provider you can set options as follows:

[source,bash]
----
bin/kc.[sh|bat] --spi-theme-selector-my-theme-selector-enabled=true --spi-theme-selector-my-theme-selector-theme=my-theme
----

Then you can retrieve the config in the `ProviderFactory` init method:

[source,java]
----
public void init(Config.Scope config) {
    String themeName = config.get("theme");
}
----

Your provider can also look up other providers if needed. For example:

[source,java]
----
public class MyThemeSelectorProvider implements ThemeSelectorProvider {

    private KeycloakSession session;

    public MyThemeSelectorProvider(KeycloakSession session) {
        this.session = session;
    }

    @Override
    public String getThemeName(Theme.Type type) {
        return session.getContext().getRealm().getLoginTheme();
    }
}
----

[[_override_builtin_providers]]
==== Override built-in providers

As mentioned above, it is recommended that your `ProviderFactory` implementations use unique ID. However at the same time, it can be useful to override one of the {project_name} built-in providers.
The recommended way for this is still ProviderFactory implementation with unique ID and then for instance set the default provider as
specified in the link:https://www.keycloak.org/server/configuration-provider[Configuring Providers] guide. On the other hand, this may not be always possible.

For instance when you need some customizations to default OpenID Connect protocol behaviour and you want to override
default {project_name} implementation of `OIDCLoginProtocolFactory` you need to preserve same providerId. As for example admin console, OIDC protocol well-known endpoint and various other things rely on
the ID of the protocol factory being `openid-connect`.

For this case, it is highly recommended to implement method `order()` of your custom implementation and make sure that it has higher order than the built-in implementation.

[source,java]
----
public class CustomOIDCLoginProtocolFactory extends OIDCLoginProtocolFactory {

    // Some customizations here

    @Override
    public int order() {
        return 1;
    }
}
----

In case of multiple implementations with same provider ID, only the one with highest order will be used by {project_name} runtime.

[[_providers_admin_console]]
==== Show info from your SPI implementation in the Admin Console

Sometimes it is useful to show additional info about your Provider to a {project_name} administrator. You can show provider build time information (for example, version of
custom provider currently installed), current configuration of the provider (e.g. url of remote system your provider talks to) or some operational info
(average time of response from remote system your provider talks to). {project_name} Admin Console provides Server Info page to show this kind of information.

To show info from your provider it is enough to implement `org.keycloak.provider.ServerInfoAwareProviderFactory` interface in your `ProviderFactory`.

Example implementation for `MyThemeSelectorProviderFactory` from previous example:

[source,java]
----
package org.acme.provider;

import ...

public class MyThemeSelectorProviderFactory implements ThemeSelectorProviderFactory, ServerInfoAwareProviderFactory {
    ...

    @Override
    public Map<String, String> getOperationalInfo() {
        Map<String, String> ret = new LinkedHashMap<>();
        ret.put("theme-name", "my-theme");
        return ret;
    }
}
----

[[_use_available_providers]]
=== Use available providers

In your provider implementation, you can use other providers available in {project_name}. The existing providers can be typically retrieved with the
usage of the `KeycloakSession`, which is available to your provider as described in the section <<_implementing_spi,Implementing an SPI>>.

{project_name} has two provider types:

* *Single-implementation provider types* - There can be only a single active implementation of the particular provider type in {project_name} runtime.
+
For example `HostnameProvider` specifies the hostname to be used by {project_name} and that is shared for the whole {project_name} server.
Hence there can be only single implementation of this provider active for the {project_name} server. If there are multiple provider implementations available to the server runtime,
one of them needs to be specified as the default one.

For example such as:
[source,bash]
----
bin/kc.[sh|bat] build --spi-hostname-provider=default
----

The value `default` used as the value of `default-provider` must match the ID returned by the `ProviderFactory.getId()` of the particular provider factory implementation.
In the code, you can obtain the provider such as `keycloakSession.getProvider(HostnameProvider.class)`

* *Multiple implementation provider types* - Those are provider types, that allow multiple implementations available and working together
in the {project_name} runtime.
+
For example `EventListener` provider allows to have multiple implementations available and registered, which means
that particular event can be sent to all the listeners (jboss-logging, sysout etc). In the code, you can obtain a specified instance of the provider
for example such as `session.getProvider(EventListener.class, "jboss-logging")` . You need to specify `provider_id` of the provider as the second argument
as there can be multiple instances of this provider type as described above.
+
The provider ID must match the ID returned by the `ProviderFactory.getId()` of the
particular provider factory implementation. Some provider types can be retrieved with the usage of `ComponentModel` as the second argument and some (for example `Authenticator`) even
need to be retrieved with the usage of `KeycloakSessionFactory`. It is not recommended to implement your own providers this way as it may be deprecated in the future.

=== Registering provider implementations

Providers are registered with the server by simply copying them to the `providers` directory.

If your provider needs additional dependencies not already provided by Keycloak copy these to the `providers` directory.

After registering new providers or dependencies Keycloak needs to be re-built with the `kc.[sh|bat] build` command.

==== Disabling a provider

You can disable a provider by setting the enabled attribute for the provider to false.
For example to disable the Infinispan user cache provider use:

[source,bash]
----
bin/kc.[sh|bat] build --spi-user-cache-infinispan-enabled=false
----

[[_script_providers]]
=== JavaScript providers

{project_name} has the ability to execute scripts during runtime in order to allow administrators to customize specific functionalities:

* Authenticator
* JavaScript Policy
* OpenID Connect Protocol Mapper
* SAML Protocol Mapper

==== Authenticator

Authentication scripts must provide at least one of the following functions:
`authenticate(..)`, which is called from `Authenticator#authenticate(AuthenticationFlowContext)`
`action(..)`, which is called from `Authenticator#action(AuthenticationFlowContext)`

Custom `Authenticator` should at least provide the `authenticate(..)` function.
You can use the `javax.script.Bindings` script within the code.

`script`::
the `ScriptModel` to access script metadata
`realm`::
the `RealmModel`
`user`::
the current `UserModel`
`session`::
the active `KeycloakSession`
`authenticationSession`::
the current `AuthenticationSessionModel`
`httpRequest`::
the current `org.jboss.resteasy.spi.HttpRequest`
`LOG`::
a `org.jboss.logging.Logger` scoped to `ScriptBasedAuthenticator`

NOTE: You can extract additional context information from the `context` argument passed to the `authenticate(context)` `action(context)` function.

[source,javascript]
----
AuthenticationFlowError = Java.type("org.keycloak.authentication.AuthenticationFlowError");

function authenticate(context) {

  LOG.info(script.name + " --> trace auth for: " + user.username);

  if (   user.username === "tester"
      && user.getAttribute("someAttribute")
      && user.getAttribute("someAttribute").contains("someValue")) {

      context.failure(AuthenticationFlowError.INVALID_USER);
      return;
  }

  context.success();
}
----

==== Create a JAR with the scripts to deploy

NOTE: JAR files are regular ZIP files with a `.jar` extension.

In order to make your scripts available to {project_name} you need to deploy them to the server. For that, you should create
a `JAR` file with the following structure:

[source]
----
META-INF/keycloak-scripts.json

my-script-authenticator.js
my-script-policy.js
my-script-mapper.js
----

The `META-INF/keycloak-scripts.json` is a file descriptor that provides metadata information about the scripts you want to deploy. It is a JSON file with the following structure:

```json
{
    "authenticators": [
        {
            "name": "My Authenticator",
            "fileName": "my-script-authenticator.js",
            "description": "My Authenticator from a JS file"
        }
    ],
    "policies": [
        {
            "name": "My Policy",
            "fileName": "my-script-policy.js",
            "description": "My Policy from a JS file"
        }
    ],
    "mappers": [
        {
            "name": "My Mapper",
            "fileName": "my-script-mapper.js",
            "description": "My Mapper from a JS file"
        }
    ],
    "saml-mappers": [
        {
            "name": "My Mapper",
            "fileName": "my-script-mapper.js",
            "description": "My Mapper from a JS file"
        }
    ]
}
```

This file should reference the different types of script providers that you want to deploy:

* `authenticators`
+
For OpenID Connect Script Authenticators. You can have one or multiple authenticators in the same JAR file
+
* `policies`
+
For JavaScript Policies when using {project_name} Authorization Services. You can have one or multiple policies in the same JAR file
+
* `mappers`
+
For OpenID Connect Script Protocol Mappers. You can have one or multiple mappers in the same JAR file
+
* `saml-mappers`
+
For SAML Script Protocol Mappers. You can have one or multiple mappers in the same JAR file

For each script file in your `JAR` file, you need a corresponding entry in `META-INF/keycloak-scripts.json` that maps your scripts files to a specific provider type. For that you should provide the following properties for each entry:

* `name`
+
A friendly name that will be used to show the scripts through the {project_name} Administration Console. If not provided, the name
of the script file will be used instead
+
* `description`
+
An optional text that better describes the intend of the script file
+
* `fileName`
+
The name of the script file. This property is *mandatory* and should map to a file within the JAR.

==== Deploy the script JAR

Once you have a JAR file with a descriptor and the scripts you want to deploy, you just need to copy the JAR to the {project_name} `providers/` directory, then run `bin/kc.[sh|bat] build`.

=== Available SPIs

If you want to see list of all available SPIs at runtime, you can check `Server Info` page in Admin Console as described in <<_providers_admin_console,Admin Console>> section.
