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Chapter 12. Switch back to the primary site

These procedures switch back to the primary site back after a failover or switchover to the secondary site. In a setup as outlined in Concepts for active-passive deployments together with the blueprints outlined in Building blocks active-passive deployments.

12.1. When to use this procedure
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These procedures bring the primary site back to operation when the secondary site is handling all the traffic. At the end of the chapter, the primary site is online again and handles the traffic.

This procedure is necessary when the primary site has lost its state in Data Grid, a network partition occurred between the primary and the secondary site while the secondary site was active, or the replication was disabled as described in the Switch over to the secondary site chapter.

If the data in Data Grid on both sites is still in sync, the procedure for Data Grid can be skipped.

See the Multi-site deployments chapter for different operational procedures.

12.2. Procedures
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12.2.1. Data Grid Cluster
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For the context of this chapter, Site-A is the primary site, recovering back to operation, and Site-B is the secondary site, running in production.

After the Data Grid in the primary site is back online and has joined the cross-site channel (see Deploy Data Grid for HA with the Data Grid Operator#verifying-the-deployment on how to verify the Data Grid deployment), the state transfer must be manually started from the secondary site.

After clearing the state in the primary site, it transfers the full state from the secondary site to the primary site, and it must be completed before the primary site can start handling incoming requests.

Warning

Transferring the full state may impact the Data Grid cluster perform by increasing the response time and/or resources usage.

The first procedure is to delete any stale data from the primary site.

  1. Log in to the primary site.

  2. Shutdown Red Hat build of Keycloak. This action will clear all Red Hat build of Keycloak caches and prevents the state of Red Hat build of Keycloak from being out-of-sync with Data Grid.

    When deploying Red Hat build of Keycloak using the Red Hat build of Keycloak Operator, change the number of Red Hat build of Keycloak instances in the Red Hat build of Keycloak Custom Resource to 0.

  3. Connect into Data Grid Cluster using the Data Grid CLI tool:

    Command:

    oc -n keycloak exec -it pods/infinispan-0 -- ./bin/cli.sh --trustall --connect https://127.0.0.1:11222
    Copy to Clipboard Toggle word wrap

    It asks for the username and password for the Data Grid cluster. Those credentials are the one set in the Deploy Data Grid for HA with the Data Grid Operator chapter in the configuring credentials section.

    Output:

    Username: developer
Password:
[infinispan-0-29897@ISPN//containers/default]>
    Copy to Clipboard Toggle word wrap

    Note

    The pod name depends on the cluster name defined in the Data Grid CR. The connection can be done with any pod in the Data Grid cluster.

  4. Disable the replication from primary site to the secondary site by running the following command. It prevents the clear request to reach the secondary site and delete all the correct cached data.

    Command:

    site take-offline --all-caches --site=site-b
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "offlineClientSessions" : "ok",
  "authenticationSessions" : "ok",
  "sessions" : "ok",
  "clientSessions" : "ok",
  "work" : "ok",
  "offlineSessions" : "ok",
  "loginFailures" : "ok",
  "actionTokens" : "ok"
}
    Copy to Clipboard Toggle word wrap

  5. Check the replication status is offline.

    Command:

    site status --all-caches --site=site-b
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "status" : "offline"
}
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    If the status is not offline, repeat the previous step.

    Warning

    Make sure the replication is offline otherwise the clear data will clear both sites.

  6. Clear all the cached data in primary site using the following commands:

    Command:

    clearcache actionTokens
clearcache authenticationSessions
clearcache clientSessions
clearcache loginFailures
clearcache offlineClientSessions
clearcache offlineSessions
clearcache sessions
clearcache work
    Copy to Clipboard Toggle word wrap

    These commands do not print any output.

  7. Re-enable the cross-site replication from primary site to the secondary site.

    Command:

    site bring-online --all-caches --site=site-b
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "offlineClientSessions" : "ok",
  "authenticationSessions" : "ok",
  "sessions" : "ok",
  "clientSessions" : "ok",
  "work" : "ok",
  "offlineSessions" : "ok",
  "loginFailures" : "ok",
  "actionTokens" : "ok"
}
    Copy to Clipboard Toggle word wrap

  8. Check the replication status is online.

    Command:

    site status --all-caches --site=site-b
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "status" : "online"
}
    Copy to Clipboard Toggle word wrap

Now we are ready to transfer the state from the secondary site to the primary site.

  1. Log in into your secondary site.

  2. Connect into Data Grid Cluster using the Data Grid CLI tool:

    Command:

    oc -n keycloak exec -it pods/infinispan-0 -- ./bin/cli.sh --trustall --connect https://127.0.0.1:11222
    Copy to Clipboard Toggle word wrap

    It asks for the username and password for the Data Grid cluster. Those credentials are the one set in the Deploy Data Grid for HA with the Data Grid Operator chapter in the configuring credentials section.

    Output:

    Username: developer
Password:
[infinispan-0-29897@ISPN//containers/default]>
    Copy to Clipboard Toggle word wrap

    Note

    The pod name depends on the cluster name defined in the Data Grid CR. The connection can be done with any pod in the Data Grid cluster.

  3. Trigger the state transfer from the secondary site to the primary site.

    Command:

    site push-site-state --all-caches --site=site-a
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "offlineClientSessions" : "ok",
  "authenticationSessions" : "ok",
  "sessions" : "ok",
  "clientSessions" : "ok",
  "work" : "ok",
  "offlineSessions" : "ok",
  "loginFailures" : "ok",
  "actionTokens" : "ok"
}
    Copy to Clipboard Toggle word wrap

  4. Check the replication status is online for all caches.

    Command:

    site status --all-caches --site=site-a
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "status" : "online"
}
    Copy to Clipboard Toggle word wrap

  5. Wait for the state transfer to complete by checking the output of push-site-status command for all caches.

    Command:

    site push-site-status --cache=actionTokens
site push-site-status --cache=authenticationSessions
site push-site-status --cache=clientSessions
site push-site-status --cache=loginFailures
site push-site-status --cache=offlineClientSessions
site push-site-status --cache=offlineSessions
site push-site-status --cache=sessions
site push-site-status --cache=work
    Copy to Clipboard Toggle word wrap

    Output:

    {
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
{
  "site-a" : "OK"
}
    Copy to Clipboard Toggle word wrap

    Check the table in this section for the Cross-Site Documentation for the possible status values.

    If an error is reported, repeat the state transfer for that specific cache.

    Command:

    site push-site-state --cache=<cache-name> --site=site-a
    Copy to Clipboard Toggle word wrap

  6. Clear/reset the state transfer status with the following command

    Command:

    site clear-push-site-status --cache=actionTokens
site clear-push-site-status --cache=authenticationSessions
site clear-push-site-status --cache=clientSessions
site clear-push-site-status --cache=loginFailures
site clear-push-site-status --cache=offlineClientSessions
site clear-push-site-status --cache=offlineSessions
site clear-push-site-status --cache=sessions
site clear-push-site-status --cache=work
    Copy to Clipboard Toggle word wrap

    Output:

    "ok"
"ok"
"ok"
"ok"
"ok"
"ok"
"ok"
"ok"
    Copy to Clipboard Toggle word wrap

  7. Log in to the primary site.

  8. Start Red Hat build of Keycloak.

    When deploying Red Hat build of Keycloak using the Red Hat build of Keycloak Operator, change the number of Red Hat build of Keycloak instances in the Red Hat build of Keycloak Custom Resource to the original value.

Both Data Grid clusters are in sync and the switchover from secondary back to the primary site can be performed.

12.2.2. AWS Aurora Database
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Assuming a Regional multi-AZ Aurora deployment, the current writer instance should be in the same region as the active Red Hat build of Keycloak cluster to avoid latencies and communication across availability zones.

Switching the writer instance of Aurora will lead to a short downtime. The writer instance in the other site with a slightly longer latency might be acceptable for some deployments. Therefore, this situation might be deferred to a maintenance window or skipped depending on the circumstances of the deployment.

To change the writer instance, run a failover. This change will make the database unavailable for a short time. Red Hat build of Keycloak will need to re-establish database connections.

To fail over the writer instance to the other AZ, issue the following command: 

aws rds failover-db-cluster  --db-cluster-identifier ...
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12.2.3. Route53
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If switching over to the secondary site has been triggered by changing the health endpoint, edit the health check in AWS to point to a correct endpoint (health/live). After some minutes, the clients will notice the change and traffic will gradually move over to the secondary site.

12.3. Further reading
링크 복사

See Concepts to automate Data Grid CLI commands on how to automate Infinispan CLI commands.

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