How to get which broker is in control in HA pair (primary or backup) programmatically

Hi @tejchowsalkar, welcome to the community!

For broker-level / system-level commands, you'll find SEMPv1 to be your friend. Something like this will work:

curl -u admin:admin http://localhost:8080/SEMP -d '<rpc><show><redundancy/></show></rpc>' | grep activity

The health check just returns 200 OK if the broker active, otherwise something else. https://docs.solace.com/Admin/Load-Balancer-Health-Check.htm

Uli's way is probably the better / less complicated option.

I'm not sure why you're getting a schema validation error, works for me??

$ curl -u admin:admin http://localhost:8080/SEMP -d '<rpc><show><redundancy/></show></rpc>'

<rpc-reply semp-version="soltr/10_3_1VMR">
  <rpc>
    <show>
      <redundancy>
        <config-status>Shutdown</config-status>
        <redundancy-status>Down</redundancy-status>
        <operating-mode>Message Routing Node</operating-mode>
        <switchover-mechanism>Hostlist</switchover-mechanism>
        <auto-revert>false</auto-revert>
        <redundancy-mode>N/A</redundancy-mode>
        <active-standby-role>Primary</active-standby-role>
        <mate-router-name></mate-router-name>
        <oper-status>
          <adb-link-up>false</adb-link-up>
          <adb-hello-up>false</adb-hello-up>
        </oper-status>
...

That command has been around forever.

AH! You're using Solace Cloud. Ok, the default admin username/password won't work b/c it's scoped to just your VPN, you cannot interrogate the broker for system-level commands.

In the Cloud Console (not the PubSub+ Manager), within your specific broker if you click on "Manage", you should see something that looks like this:

The "viewers" credentials are system-level, but read-only. That username + password should work.

@uherbst it doesn't appear that 5550 is exposed for Solace Cloud? I'm trying for my test broker and it's not working, the connection just hangs. I've tried a bunch of different combinations, ports, etc. I've asked internally and will report back here. They may just not expose it since the SaaS handles everything for you via the load balancer..?

@tejchowsalkar Uli is right, the SaaS takes care of which broker to point at for you. What is the reason / use-case for trying to figure this out? There are some other options too. You can query the broker for its hostname, and (due to the load balancer) the active one will respond, so you'll know which is currently active. Something like:

curl -u my-broker-admin:password https://abc.messaging.solace.cloud:943/SEMP -d '<rpc><show><ho
stname/></show></rpc>'

"show hostname" will work with the regular admin credentials.

Ok. Thanks for the additional details. SEMP over the message bus is a whole different kettle of fish. First off: why are you looking to used SEMP-over-MB? It was an old feature that we added for particular use cases a long time ago... and it not typically considered a best practice. However, in some instances, it can be very useful.

One of the main issues with its use is that if one deployed app needs it, then often many applications that connect into Solace use the same code, and you now have dozens or hundreds of app querying for SEMP statistics... and this puts significant load on the broker's control plane. It's better to query the broker once (with a broker monitoring app), and store or distribute that data to other apps that require it.

Further: you cannot query any system-level or broker-level commands using SEMP-over-MB. Only objects available inside your VPN. See docs here: https://docs.solace.com/Admin/SEMP/Using-Legacy-SEMP.htm Specifically:

To find out the broker's router name (which can be different than the hostname), you can ask the API once you've connected to Solace. Something like:

// Extract the router name.
String routerName = (String) session.getCapability(CapabilityType.PEER_ROUTER_NAME);

final String SEMP_TOPIC_STRING = String.format("#SEMP/%s/SHOW", routerName);
final Topic SEMP_TOPIC = JCSMPFactory.onlyInstance().createTopic(SEMP_TOPIC_STRING);

Note that for SEMP-over-MB to work, you have to enable it inside your VPN's configuration. And only SEMPv1 is supported.

But again, I'd ask what your use case is? Messaging apps themselves don't usually need to poll for this info, it should be done by a management app using the HTTP SEMP interface.