How to monitor Solace as an external consumer

cl0udf0x · January 9

Hi,

I have inherited an application that consumes messages from an external Solace pub+sub system and fairly new to it.

What would be the best way to monitor from a consumer perspective?

Having been thinking of the following

check the auth
check the connection to queue
check the queue (is it possible to measure things like queue size etc?)

I hope to use an API with Python requests or use Python Client.

I appreciate any help you can provide.

cl0udf0x · January 10

I hope this helps explain what I'd like to achieve.

Keen to get some feedback etc, thanks in advance.

I've setup a local docker subpub+ using the starter guide and running the code below to test out some queries.

Note the following code is very rough and just for initial learning:

## Check the message VPN and Auth in the process

def check_message_vpn():
    apiUrl = f"http://{primaryBroker}:8080/SEMP/v2/__private_monitor__/msgVpns/{messageVpnName}?select=state"
    response = requests.get(apiUrl, auth=(apiUsername, apiPassword), verify=False)
    print(response.json())  
    try:
        response = requests.get(apiUrl, auth=(apiUsername, apiPassword), verify=False)
        if response.status_code == 200:
            vpn_state = response.json().get("data", {}).get("state", "unknown")

            if vpn_state == "up":
                print(f"Message VPN '{messageVpnName}' is up and responding correctly.")
            else:
                print(
                    f"Message VPN '{messageVpnName}' is not up. Current state: {vpn_state}"
                )
        elif response.status_code == 401:
            print("Authentication failed. Please check your username and password.")
        else:
            print(
                f"Failed to fetch the state of the message VPN. Status code: {response.status_code}"
            )
            print("Response content:", response.text)
    except requests.exceptions.RequestException as e:
        print(f"An error occurred: {e}")


## Check the queue

def check_queue_health():
    apiUrl = f"http://{primaryBroker}:8080/SEMP/v2/config/msgVpns/{messageVpnName}/queues/{queueName}"
    try:
        response = requests.get(apiUrl, auth=(apiUsername, apiPassword), verify=False)
        if response.status_code == 200:
            queue_info = response.json().get("data", {})
            ingress_enabled = queue_info.get("ingressEnabled", "unknown")
            egress_enabled = queue_info.get("egressEnabled", "unknown")
            if ingress_enabled and egress_enabled:
                print(f"Queue '{queueName}' is up and processing messages.")
            else:
                print(
                    f"Queue '{queueName}' is not processing messages correctly. Ingress: {ingress_enabled}, Egress: {egress_enabled}"
                )
        elif response.status_code == 401:
            print("Authentication failed. Please check your username and password.")
        else:
            print(
                f"Failed to fetch the state of the queue. Status code: {response.status_code}"
            )
            print("Response content:", response.text)
    except requests.exceptions.RequestException as e:
        print(f"An error occurred: {e}")

Aaron · January 14

Hey @cl0udf0x ..! Good to see you trying to use some SEMP, that's definitely the way to monitor the broker. Although, I woudn't use anything with __private_monitor__ in the URL. It's some internal API call and might change/break in the future. Looking at that line, I think you could probably just remove that part of the URL and the call should still work… just querying VPN info. More info here: https://docs.solace.com/Admin/SEMP/Using-SEMP.htm

So: you have a consumer app (in Python), and you want to monitor this app for its "health"… performance, connection, whatever. Are you looking for the app to self-monitor? Or write another application (in Python?) that also does SEMP to the broker to get your queue status? Or have the consumer app itself doing the SEMP? If the latter, I wouldn't recommend this… usually monitoring applications are kept separate from data applications. There are a couple cases where you might want to do this, but I always prefer to keep things separate since they're separate things.

It's possible to compile libraries from our SEMPv2 API, so that you can do things programmatically rather than having to parse through the raw JSON yourself. Might help?

As for what to monitor: the majority of the monitoring would probably be done on the broker side. You say the broker is "external" as in you don't control it? But you also have SEMP access to it?

For your app to self monitor, there are a number of event handlers you can register with the API: e.g. session event handler, will give you connection UP/DOWN events; flow event handler will tell you if your flow (bind to the queue) is UP/DOWN (connected) and hopefully ACTIVE (your app is live for receiving messages)… a 2nd instance of your app binding to an exclusive queue would not get the ACTIVE notification until the 1st instance unbinds and the 2nd one takes over. Obviously, within your app, you can track your own metrics by incrementing a msgRecvd int every time you get a message, and a msgProcd variable whenever your consumer app has successfully processed and ACKed a message.

For monitoring the broker: you'd want to primarily watch the queue depth (am I falling behind), and maybe also if there's messages in the queue to deliver, but either the message send rate is 0 or the lowest message ID is not increasing (a message stuck at the front). This would/could indicate a problem with your consumer app. Oh, or the bind count is 0, which means your app isn't connected.

Have you run into any issues already/previously that you're hoping to avoid with improved visibility?

cl0udf0x · January 15

Thanks so much for this detailed response. It's appreciated!

I'll digest this and respond shortly. Thanks again!

How to monitor Solace as an external consumer

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