<#import "/templates/guide.adoc" as tmpl>
<#import "/templates/kc.adoc" as kc>
<#import "/templates/links.adoc" as links>

<@tmpl.guide
title="Configuring Keycloak"
summary="Understand how to configure and start Keycloak">

This {section} explains the configuration methods for Keycloak and how to start and apply the preferred configuration. It includes configuration guidelines for optimizing Keycloak for faster startup and low memory footprint.

== Configuring sources for Keycloak
Keycloak loads the configuration from four sources, which are listed here in order of application. 

. Command-line parameters
. Environment variables
. Options defined in a user-created configuration file.
. Options defined in the `conf/keycloak.conf` file.

When an option is set in more than one source, the one that comes first in the list determines the value for that option. For example, the value for an option set by a command-line parameter has a higher priority than an environment variable for the same option.

=== Example: Configuring the db-url-host parameter

The following example shows how the `db-url` value is set in three configuration sources:

|===
|*Source* | *Format*

|Command line parameters
|`--db-url=cliValue`

|Environment variable
|`KC_DB_URL=envVarValue`

|Configuration file
|`db-url=confFileValue`
|===

Based on the priority of application, the value that is used at startup is `cliValue`, because the command line is the highest priority.

If `--db-url=cliValue` had not been used, the applied value would be `KC_DB_URL=envVarValue`. If the value were not applied by either the command line or an environment variable, `db-url=confFileValue` would be used. However, if this value had been set in a user defined configuration file, that value would take precedence over the `conf/keycloak.conf` file.

== Formats for configuration
The configuration uses a _unified-per-source_ format, which simplifies translation of a key/value pair from one configuration source to another.

Command-line parameter format:: Values for the command-line use the `--_<key-with-dashes>_=_<value>_` format. For some values, an `-_<abbreviation>_=_<value>_` shorthand also exists.

Environment variable format:: Values for environment variables use the uppercased `KC++_++__<key_with_underscores>__=_<value>_` format.

Configuration file format:: Values that go into the configuration file use the `_<key-with-dashes>_=_<value>_` format.

At the end of each configuration {section}, look for the _Relevant
options_ heading, which defines the applicable configuration
formats. For all configuration options, see <@links.server
id="all-config"/>.  Choose the configuration source and format that applies to your use case.

=== Example - Alternative formats based on configuration source
The following example shows the configuration format for `db-url-host` for three configuration sources:

.command-line parameter
<@kc.start parameters="--db-url-host=mykeycloakdb"/>

.environment variable
[source]
----
export KC_DB_URL_HOST=mykeycloakdb
----

.conf/keycloak.conf
[source]
----
db-url-host=mykeycloakdb
----

=== Formats for command-line parameters

Keycloak is packed with many command line parameters for configuration. To see the available configuration formats, enter the following command:

<@kc.start parameters="--help"/>

Alternatively, see <@links.server id="all-config"/> for all server options.

=== Formats for environment variables
You can use placeholders to resolve an environment specific value from environment variables inside the `keycloak.conf` file by using the `${r"++${ENV_VAR}++"}` syntax:

[source]
----
db-url-host=${r"${MY_DB_HOST}"}
----

In case the environment variable cannot be resolved, you can specify a fallback value. Use a `:` (colon) as shown here before  `mydb`:
[source, bash]
----
db-url-host=${r"${MY_DB_HOST:mydb}"}
----

=== Format to include a specific configuration file

By default, the server always fetches configuration options from the `conf/keycloak.conf` file. For a new installation, this file holds only commented settings as an idea of what you want to set when running in production.

You can also specify an explicit configuration file location using the `[-cf|--config-file]` option by entering the following command:

<@kc.start rootParameters="--config-file=/path/to/myconfig.conf"/>

=== Format for raw Quarkus properties
In most cases, the available configuration options should suffice to configure the server. 
However, for a specific behavior or capability that is missing in the Keycloak configuration, you can use properties from the underlying Quarkus framework.

If possible, avoid using properties directly from Quarkus, because they are unsupported by Keycloak. If your need is essential, consider opening an https://github.com/keycloak/keycloak/issues/new?assignees=&labels=kind%2Fenhancement%2Cstatus%2Ftriage&template=enhancement.yml[enhancement request] first.  This approach helps us improve the configuration of Keycloak to fit your needs.

If an enhancement request is not possible, you can configure the server using raw Quarkus properties:

. Create a `quarkus.properties` file in the `conf` directory.
. Define the required properties in that file.
+
You can use only a https://github.com/keycloak/keycloak/blob/main/quarkus/runtime/pom.xml#L17[subset] of the Quarkus extensions that are defined in the https://quarkus.io/guides/all-config[Quarkus documentation]. Also, note these differences for Quarkus properties:

* A lock icon for a Quarkus property in the https://quarkus.io/guides/all-config[Quarkus documentation] indicates a build time property.  You run the `build` command to apply this property. For details about the build command, see the subsequent sections on optimizing Keycloak.
* No lock icon for a property in the Quarkus guide indicates a runtime property for Quarkus and Keycloak. 

. Use the `[-cf|--config-file]` command line parameter to include that file.

Note that some Quarkus properties are already mapped in the Keycloak configuration, such as `quarkus.http.port` and similar essential properties. If the property is used by Keycloak, defining that property key in `quarkus.properties` has no effect. The Keycloak configuration value takes precedence over the Quarkus property value.

== Starting Keycloak
You can start Keycloak in `development mode` or `production mode`. Each mode offers different defaults for the intended environment.

=== Starting Keycloak in development mode
Use development mode to try out Keycloak for the first time to get it up and running quickly. This mode offers convenient defaults for developers, such as for developing a new Keycloak theme.

To start in development mode, enter the following command:

<@kc.startdev parameters=""/>

.Defaults
Development mode sets the following default configuration:

* HTTP is enabled
* Strict hostname resolution is disabled
* Cache is set to local (No distributed cache mechanism used for high availability)
* Theme-caching and template-caching is disabled

=== Starting Keycloak in production mode
Use production mode for deployments of Keycloak in production environments. This mode follows a _secure by default_ principle.

To start in production mode, enter the following command:

<@kc.start parameters=""/>

Without further configuration, this command will not start Keycloak and show you an error instead. This response is done on purpose, because Keycloak follows a _secure by default_ principle. Production mode expects a hostname to be set up and an HTTPS/TLS setup to be available when started.

.Defaults
Production mode sets the following defaults:

* HTTP is disabled as transport layer security (HTTPS) is essential
* Hostname configuration is expected
* HTTPS/TLS configuration is expected

Before deploying Keycloak in a production environment, make sure to follow the steps outlined in <@links.server id="configuration-production"/>.

By default, example configuration options for the production mode are commented out in the default `conf/keycloak.conf` file. These options give you an idea about the main configuration to consider when running Keycloak in production.

== Creating the initial admin user
You can create the initial admin user by using the web frontend, which you access using a local connection (localhost). You can instead create this user by using environment variables. Set `KEYCLOAK_ADMIN=_<username>_` for the initial admin username and `KEYCLOAK_ADMIN_PASSWORD=_<password>_` for the initial admin password.

Keycloak parses these values at first startup to create an initial user with administrative rights.
Once the first user with administrative rights exists, you can use the Admin Console or the command line tool `kcadm.[sh|bat]` to create additional users.

If the initial administrator already exists and the environment variables are still present at startup, an error message stating the failed creation of the initial administrator is shown in the logs. Keycloak ignores the values and starts up correctly.

== Optimize the Keycloak startup
We recommend optimizing Keycloak to provide faster startup and better memory consumption before deploying Keycloak in a production environment. This section describes how to apply Keycloak optimizations for the best performance and runtime behavior.

=== Creating an optimized Keycloak build
By default, when you use the `start` or `start-dev` command, Keycloak runs a `build` command under the covers for convenience reasons.  

This `build` command performs a set of optimizations for the startup and runtime behavior. The build process can take a few seconds. Especially when running Keycloak in containerized environments such as Kubernetes or OpenShift, startup time is important. To avoid losing that time, run a `build` explicity before starting up, such as a separate step in a CI/CD pipeline.

==== First step: Run a build explicitly
To run a `build`, enter the following command:

<@kc.build parameters="<build-options>"/>

This command shows `build options` that you enter. Keycloak distinguishes between **build options**, that are usable when running the `build` command, and **configuration options**, that are usable when starting up the server.

For a non-optimized startup of Keycloak, this distinction has no effect. However, if you run a build before the startup,  only a subset of options is available to the build command. The restriction is due to the build options getting persisted into an optimized Keycloak image. For example, configuration for credentials such as `db-password` must not get persisted for security reasons.

Build options are marked in <@links.server id="all-config"/> with a tool icon.
To find available build options, see https://www.keycloak.org/server/all-config?f=build[All configuration page with build options selected] or enter the following command:

<@kc.build parameters="--help"/>

.Example: Run a `build` to set the database to PostgreSQL before startup
<@kc.build parameters="--db=postgres"/>

==== Second step: Start Keycloak using `--optimized`
After a successful build, you can start Keycloak and turn off the default startup behavior by entering the following command:

<@kc.start parameters="--optimized <configuration-options>"/>

The `--optimized` parameter tells Keycloak to assume a pre-built, already optimized Keycloak image is used. As a result, Keycloak avoids checking for and running a build directly at startup, which saves time.

You can enter all configuration options at startup; these options are the ones in <@links.server id="all-config"/> that are **not** marked with a tool icon.

* If a build option is found at startup with a value that is equal to the value used when entering the `build`, that option gets silently ignored when you use the `--optimized` parameter.
* If that option has a different value than the value used when a build was entered, a warning appers in the logs and the previously built value is used. For this value to take effect, run a new `build` before starting.

.Create an optimized build

The following example shows the creation of an optimized build followed by the use of the `--optimized` parameter when starting Keycloak.

. Set the build option for the PostgreSQL database vendor using the build command
+
    <@kc.build parameters="--db=postgres"/>

. Set the runtime configuration options for postgres in the `conf/keycloak.conf` file.
+
[source]
----
db-url-host=keycloak-postgres
db-username=keycloak
db-password=change_me
hostname=mykeycloak.acme.com
https-certificate-file
----

. Start the server with the optimized parameter
+
    <@kc.start parameters="--optimized"/>

You can achieve most optimizations to startup and runtime behavior by using the `build` command. Also, by using the `keycloak.conf` file as a configuration source, you avoid some steps at startup that would otherwise require command line parameters, such as initializing the CLI itself. As a result, the server starts up even faster.

== Underlying concepts
This section gives an overview of the underlying concepts Keycloak uses, especially when it comes to optimizing the startup.

Keycloak uses the Quarkus framework and a re-augmentation/mutable-jar approach under the covers. This process is started when a `build` command is run.

The following are some optimizations performed by the `build` command:

* A new closed-world assumption about installed providers is created, meaning that no need exists to re-create the registry and initialize the factories at every Keycloak startup.
* Configuration files are pre-parsed to reduce I/O when starting the server.
* Database specific resources are configured and prepared to run against a certain database vendor.
* By persisting build options into the server image, the server does not perform any additional step to interpret configuration options and (re)configure itself.

You can read more at the specific https://quarkus.io/guides/reaugmentation[Quarkus guide]

</@tmpl.guide>
