= Infinispan marshalling changes

Marshalling is the process of converting Java objects into bytes to send them across the network between {project_name} servers.
With {project_name} 26, the marshalling library has changed from JBoss Marshalling to Infinispan Protostream.
The libraries are not compatible between each other and, it requires some steps to ensure the session data is not lost.

WARNING: JBoss Marshalling and Infinispan Protostream are not compatible with each other and incorrect usage may lead to data loss.
Consequently, all caches are cleared when upgrading to this version.

To prevent losing user sessions upgrade to Keycloak 25 first and enable the persistent sessions feature as outlined in the migration guide for {project_name} 25.

= Operator no longer defaults to proxy=passthrough

The Operator will no longer default to the hostname v1 setting of proxy=passthrough. This allows deployments using hostname v2 for a fixed edge hostname to work as desired without additional options.

= New method in `ClusterProvider` API

The following method was added to `org.keycloak.cluster.ClusterProvider`:

* `void notify(String taskKey, Collection<? extends ClusterEvent> events, boolean ignoreSender, DCNotify dcNotify)`

When multiple events are sent to the same `taskKey`, this method batches events and just perform a single network call.
This is an optimization to reduce traffic and network related resources.

In {project_name} 26, the new method has a default implementation to keep backward compatibility with custom implementation.
The default implementation performs a single network call per an event, and it will be removed in a future version of {project_name}.

= Group-related events no longer fired when removing a realm

With the goal of improving the scalability of groups, they are now removed directly from the database when removing a realm.
As a consequence, group-related events like the `GroupRemovedEvent` are no longer fired when removing a realm.

If you have extensions handling any group-related event when a realm is removed, make sure to use the `RealmRemovedEvent` instead
to perform any cleanup or custom processing when a realm, and their groups, are removed.

The `GroupProvider` interface is also updated with a new `preRemove(RealmModel)` method to force implementations to properly
handle the removal of groups when a realm is removed.

= Operator scheduling defaults

Keycloak Pods will now have default affinities to prevent multiple instances from the same CR from being deployed on the same node, and all Pods from the same CR will prefer to be in the same zone to prevent stretch cache clusters.

= Operator's default CPU and memory limits/requests

In order to follow the best practices, the default CPU and memory limits/requests for the Operator were introduced. It affects both non-OLM and OLM installs. To override the default values for the OLM install, edit the `resources` section in the operator's https://github.com/operator-framework/operator-lifecycle-manager/blob/master/doc/design/subscription-config.md#resources[subscription].

= Deprecations in `keycloak-common` module

The following items have been deprecated for removal in upcoming {project_name} versions with no replacement:

- `org.keycloak.common.util.reflections.Reflections.newInstance(java.lang.Class<T>)`
- `org.keycloak.common.util.reflections.Reflections.newInstance(java.lang.Class<?>, java.lang.String)`
- `org.keycloak.common.util.reflections.SetAccessiblePrivilegedAction`
- `org.keycloak.common.util.reflections.UnSetAccessiblePrivilegedAction`

= Consistent usage of UTF-8 charset for URL encoding

`org.keycloak.common.util.Encode` now always uses the `UTF-8` charset for URL encoding instead relying implicitly on the `file.encoding` system property.

= Configuring the LDAP Connection Pool

In this release, the LDAP connection pool configuration relies solely on system properties. The main
reason is that the LDAP connection pool configuration is a JVM-level configuration rather than specific to an individual
realm or LDAP provider instance.

Compared to previous releases, any realm configuration related to the LDAP connection pool will be ignored.
If you are migrating from previous versions where any of the following settings are set to your LDAP provider(s), consider using system properties instead:

* `connectionPoolingAuthentication`
* `connectionPoolingInitSize`
* `connectionPoolingMaxSize`
* `connectionPoolingPrefSize`
* `connectionPoolingTimeout`
* `connectionPoolingProtocol`
* `connectionPoolingDebug`

For more details, see link:{adminguide_link}#_ldap_connection_pool[Configuring the connection pool].

= Custom Footer in Login Theme

This release introduced the capability to easily add a custom footer to the login pages for the `base/login` and `keycloak.v2/login` theme.
In order to use a custom footer, create a `footer.ftl` file in your custom login theme with the desired content.

For more details, see link:{developerguide_link}#_theme_custom_footer[Adding a custom footer to a login theme].

= Persisting revoked access tokens across restarts

In this release, revoked access tokens are written to the database and reloaded when the cluster is restarted by default when using the embedded caches.

To disable this behavior, use the SPI option `spi-single-use-object-infinispan-persist-revoked-tokens` as outlined in the https://www.keycloak.org/server/all-provider-config[All provider configuration] {section}.

The SPI behavior of `SingleUseObjectProvider` has changed that for revoked tokens only the methods `put` and `contains` must be used.
This is enforced by default, and can be disabled using the SPI option `spi-single-use-object-infinispan-persist-revoked-tokens`.

= Highly available multi-site deployments

{project_name} 26 introduces significant improvements to the recommended HA multi-site architecture, most notably:

- {project_name} deployments on each site are now able to handle user requests simultaneously, therefore active/active
setups are now supported, while previous configurations which leveraged active/passive loadbalancer will continue to work.

- The loadbalancer blueprint has been updated to use the AWS Global Accelerator as this avoids prolonged fail-over times
caused by DNS caching by clients.

- Persistent user sessions are now a requirement of the architecture. Consequently, user sessions will be kept
on {project_name} or {jdgserver_name} upgrades.

- External {jdgserver_name} request handling has been improved to reduce memory usage and request latency.

As a consequence of the above changes, the following changes are required to your existing {project_name} deployments.

. `distributed-cache` definitions provided by a cache configuration file are ignored when the `multi-site` feature is enabled,
so you must configure the connection to the external {jdgserver_name} deployment via the `cache-remote-*` command line arguments
or Keycloak CR as outlined in the blueprints. If a `remote-store` configuration is detected in the cache configuration file,
then a warning will be raised in the {project_name} logs.

. Review your current cache configurations in the external {jdgserver_name} and update them with those outlined in the latest version of the {project_name}'s documentation.

. While previous LoadBalancer configurations will continue to work with {project_name}, consider upgrading
an existing Route53 configurations to avoid prolonged failover times due to client side DNS caching.

= Admin Bootstrapping and Recovery

It used to be difficult to regain access to a {project_name} instance when all admin users were locked out. The process required multiple advanced steps, including direct database access and manual changes. In an effort to improve the user experience, {project_name} now provides multiple ways to bootstrap a new admin account, which can be used to recover from such situations.

Consequently, the environment variables `KEYCLOAK_ADMIN` and `KEYCLOAK_ADMIN_PASSWORD` have been deprecated. You should use `KC_BOOTSTRAP_ADMIN_USERNAME` and `KC_BOOTSTRAP_ADMIN_PASSWORD` instead. These are also general options, so they may be specified via the cli or other config sources, for example `--bootstrap-admin-username=admin`. For more information, see the new https://www.keycloak.org/server/bootstrap-admin-recovery[Bootstrap admin and recovery] guide.

= Deprecations in `keycloak-services` module

The class `UserSessionCrossDCManager` is deprecated and planned to be removed in a future version of {project_name}.
Read the `UserSessionCrossDCManager` Javadoc for the alternative methods to use.

= Identity Providers no longer available from the realm representation

As part of the improvements around the scalability of realms and organizations when they have many identity providers, the realm representation
no longer holds the list of identity providers. However, they are still available from the realm representation
when exporting a realm.

To obtain the query the identity providers in a realm, prefer using the `/realms/{realm}/identity-provider/instances` endpoint.
This endpoint supports filters and pagination.

= CLI import placeholder replacement

The CLI command `kc.[sh|bat] import` now has placeholder replacement enabled. Previously placeholder replacement was only enabled for realm import at startup.

If you wish to disable placeholder replacement for the `import` command, add the system property `-Dkeycloak.migration.replace-placeholders=false`

= New Java API to search realms by name

The `RealmProvider` Java API now contains a new method `Stream<RealmModel> getRealmsStream(String search)` which allows searching for a realm by name.
While there is a default implementation which filters the stream after loading it from the provider, implementations are encouraged to provide this with more efficient implementation.

= Keystore and trust store default format change

{project_name} now determines the format of the keystore and trust store based on the file extension. If the file extension is `.p12`, `.pkcs12` or `.pfx`, the format is PKCS12. If the file extension is `.jks`, `.keystore` or `.truststore`, the format is JKS. If the file extension is `.pem`, `.crt` or `.key`, the format is PEM.

You can still override automatic detection by specifying the `https-key-store-type` and `https-trust-store-type` explicitly. The same applies to the management interface and its `https-management-key-store-type`. Restrictions for the FIPS strict mode stay unchanged.

NOTE: The `+spi-truststore-file-*+` options and the truststore related options `+https-trust-store-*+` are deprecated, we strongly recommend to use System Truststore. For more details refer to the relevant https://www.keycloak.org/server/keycloak-truststore[guide].

= Improving performance for selection of identity providers

New indexes were added to the `IDENTITY_PROVIDER` table to improve the performance of queries that fetch the IDPs associated with an organization, and fetch IDPs that are available for login (those that are `enabled`, not `link_only`, not marked as `hide_on_login`).

If the table currently contains more than 300.000 entries,
{project_name} will skip the creation of the indexes by default during the automatic schema migration, and will instead log the SQL statements
on the console during migration. In this case, the statements must be run manually in the DB after {project_name}'s startup.

Also, the `kc.org` and `hideOnLoginPage` configuration attributes were migrated to the identity provider itself, to allow for more efficient queries when searching for providers. As such, API clients should use the `getOrganizationId/setOrganizationId` and `isHideOnLogin/setHideOnLogin` methods in the `IdentityProviderRepresentation`, and avoid setting these properties using the legacy config attributes that are now deprecated.

= Removal of GELF logging handler

GELF support has been deprecated for a while now, and with this release it has been finally removed from {project_name}.
Other log handlers are available and fully supported to be used as a replacement of GELF, for example Syslog. For details
see the https://www.keycloak.org/server/logging[Logging guide].

= Paths for `common` theme resources have changed

Some of the paths for the `common` resources of the `keycloak` theme have changed, specifically the resources for third-party libraries. Make sure to update your custom themes accordingly:

- `node_modules/patternfly/dist` is now `vendor/patternfly-v3`
- `node_modules/@patternfly/patternfly` is now `vendor/patternfly-v4`
- `node_modules/@patternfly-v5/patternfly` is now `vendor/patternfly-v5`
- `node_modules/rfc4648/lib` is now `vendor/rfc4648`

Additionally, the following resources have been removed from the `common` theme:

- `node_modules/alpinejs`
- `node_modules/jquery`

If you previously used any of the removed resources in your theme, make sure to add them to your own theme resources instead.

= Additional datasources now require using XA

{project_name} by default does not use XA datasources. However, this is considered unsafe if more than one datasource is used.
Starting with this release, you need to use XA datasources if you are adding additional datasources to {project_name}.
If the default datasource supports XA, you can do this by setting the `--transaction-xa-enabled=true` option. For additional datasources, you need to use
the `quarkus.datasource.<your-datasource-name>.jdbc.transactions=xa` option in your `quarkus.properties` file.
At most one datasource can be non-XA.
Recovery isn't supported when you don't have persistent storage for the transaction store.

= Hostname v1 feature removed

The deprecated hostname v1 feature was removed. This feature was deprecated in {project_name} 25 and replaced by hostname v2. If you are still using this feature, you must migrate to hostname v2. For more details, see the https://www.keycloak.org/server/hostname[Configuring the hostname (v2)] and https://www.keycloak.org/docs/latest/upgrading/#new-hostname-options[the initial migration guide].

= Proxy option removed

The deprecated `proxy` option was removed. This option was deprecated in {project_name} 24 and replaced by the `proxy-headers` option in combination with hostname options as needed. For more details, see https://www.keycloak.org/server/reverseproxy[using a reverse proxy] and https://www.keycloak.org/docs/latest/upgrading/index.html#deprecated-proxy-option[the initial upgrading guide].
