Configure SRM for Failover and Failback

Learn how to configure SRM for failover and failback.

To prepare for a failover or failback scenario you have to set up SRM with bidirectional replication. Additionally, you have to make sure that all mission critical topics and consumer groups are whitelisted on both the primary and backup clusters. Optionally, you can also choose to enable automatic group offset synchronization, which can simplify the steps you need to take when migrating consumer groups.

If you plan on enabling automatic group offset synchronization, ensure that you review Configuring automatic group offset synchronization. Although the basic steps are provided here, the feature has some limitations that you must be aware of.

In Cloudera Manager, select Streams Replication Manager.
Go to Configuration.
Set up bidirectional replication between clusters:

note

The following example contains the minimum required properties only. For a more in-depth configuration example for a cluster setup with bidirectional replication, see Configuration Examples.
1. Find the Streams Replication Manager Cluster alias property.
2. Add a comma delimited list of cluster aliases. For example:
```
primary, secondary
```
3. Find the Streams Replication Manager's Replication Configs property.
4. Click the add button and add new lines for each cluster alias you have specified in the Streams Replication Manager Cluster alias property
5. Add connection information for your clusters. For example:
```
primary.bootstrap.servers=primary_host1:9092,primary_host2:9092,primary_host3:9092
secondary.bootstrap.servers=secondary_host1:9092,secondary_host2:9092,secondary_host3:9092
```
  Each cluster has to be added to a new line. If a cluster has multiple hosts, add them to the same line but delimit them with commas.
6. Click the add button and add new lines for each unique replication you want to add and enable.
7. Add and enable your replications. For example:
```
primary->secondary.enabled=true
secondary->primary.enabled=true
```
Optional: Enable and configure automatic group offset synchronization.
This can be done by enabling sync.group.offsets.enabled. Optionally, if you want to customize the frequency of offset synchronization, you can also set sync.group.offsets.interval.seconds. Both properties are configured by adding them to Streams Replication Manager's Replication Configs. For example:
```
sync.group.offsets.enabled = true
sync.group.offsets.interval.seconds = [***TIME IN SECONDS***]
```
Enter a Reason for change, and then click Save Changes to commit the changes.
Restart Streams Replication Manager.

Whitelist required consumer groups and topics on the primary cluster.

Whitelist groups:

srm-control groups --source [PRIMARY_CLUSTER] --target [SECONDARY_CLUSTER] --add [GROUP1],[GROUP2]

Whitelist topics:

srm-control topics --source [PRIMARY_CLUSTER] --target [SECONDARY_CLUSTER] --add [TOPIC1],[TOPIC2]

Whitelist required remote topics and consumer groups on the secondary cluster.

important

If remote topics and consumer groups are not whitelisted on the secondary cluster, a failback operation will be impossible to carry out.
1. Whitelist remote groups:
```
srm-control groups --source [SECONDARY_CLUSTER] --target [PRIMARY_CLUSTER] --add [GROUP1],[GROUP2]
```
2. Whitelist remote topics:
```
srm-control topics --source [SECONDARY_CLUSTER] --target [PRIMARY_CLUSTER] --add [PRIMARY_CLUSTER.TOPIC1],[PRIMARY_CLUSTER.TOPIC2]
```

Verify that all required topics and consumer groups are whitelisted.

Verify consumer groups:

srm-control groups --source [PRIMARY_CLUSTER] --target [SECONDARY_CLUSTER] --list

srm-control groups --source [SECONDARY_CLUSTER] --target [PRIMARY_CLUSTER] --list

Verify topics:

srm-control topics --source [PRIMARY_CLUSTER] --target [SECONDARY_CLUSTER] --list

srm-control topics --source [SECONDARY_CLUSTER] --target [PRIMARY_CLUSTER] --list

SRM is set up with bidirectional replication and all mission critical topics and consumer groups are whitelisted on both the primary and secondary clusters.