Requesting more detailed information around the cons and pros of host groups

[larry_roberts]

I am at a point in our environment where I want to start defining host groups. I have some key questions however that none of the documentation seems to reach touch on or at least not in the detail I am looking for. Hoping somebody from Dynatrace can answer the following questions please. I was going to just ask support, however I thought it would be good to get these answers on the forum for others as well.

• Is it possible to set host groups for GCP/Kubernetes?
  • This is an area where it is really needed and would be of high value as we have everything from production to staging to testing hosts.

• What is the outlook on setting host groups for Solaris?
  • This is not exactly a huge issue for us as we are currently in the process of migrating what we have left on Solaris over to Linux, but still feels like a valid question.

• How and / or does setting host groups effect service merging?
  • We have done a ton of service merging within our WebLogic environment which often has up to 3 hosts within a cluster. Would this have any effect of what has been merged? We will still be able to continue service merging as new things are on-boarded?

It states in the documentation page that...

"Host groups are sets of hosts. Each group can be configured on the host-group level. This makes it easy to change the settings for a large number of hosts. You can define alerting thresholds and OneAgent update settings on a per-host-group basis."

And below that also states...

"Additionally, host groups affect how process groups are detected. When the same process is running in two different host groups, Dynatrace will create one process group for each host group. This means you can also configure process groups differently depending on which host group they run in. Consequently, services are also grouped per host group. So you can configure services differently per host group."

So what exactly does this mean in more detail?

What if you for example, adjusted the anomaly detection for a specific process , services, etc. before setting up host groups.

• Once you make a host group, does Dynatrace then override that?
• Dos it all now roll up into this host group if it exists on a server within the defined host group?

---

Outside of the big inconvenience of not being able to create, modify, or remove host groups within the GUI itself (hope Dynatrace addresses this soon), I would like to hear the pros and cons others have ran into around host groups. I see all the benefits to host groups, but what I am more concerned about are the cons (if any).

Thanks!

[joshua_dtrace · Accepted solution]

Hey Larry R.!

I can't answer all of the questions (especially about upcoming support - though I do know a roadmapped goal exists to allow host group reconfiguration via the UI ["goal" being the operative word]), but I can answer the ones about how things change after adding a host group.

Dynatrace Best Practices would dictate that configuring Host Groups should be one of the first things done (as either part of the OneAgent deployment or soon after deployment). There will be some side-effects if you're trying to configure Host Groups after-the-fact.

1. How and / or does setting host groups effect service merging?
   1. Services, as you already know, are split by their underlying process groups. So, using the built-in UI functionality of Merged Services you can't merge two service entities if they're in separate process groups.
   2. When you introduce host groups in your environment (and restart your processes), host groups will split up process groups if the process instances are in different host groups. This is just like the relationship between services and their underlying process groups.
      • One Host Group can have multiple Process Groups
      • One Process Group can only have one underlying Host Group (Process Groups cannot transcend Host Groups)
      • One Service can only have one underlying Process Group (Services cannot transcend Process Groups)
   3. Here is the documentation (and two blog posts) for the new way that we recommend customers merge Services going forward. The previous functionality was restricted by process groups. This new method is not:
      1. https://www.dynatrace.com/news/blog/new-dynatrace-api-enhances-automatic-service-detection/
      2. https://www.dynatrace.com/news/blog/new-dynatrace-api-enhances-automatic-service-detection-part-2/
      3. https://www.dynatrace.com/support/help/extend-dynatrace/dynatrace-api/configuration-api/service-api/...

1. What if you for example, adjusted the anomaly detection for a specific process , services, etc. before setting up host groups.
   1. Host groups will create brand new process groups (because the underlying composition of the process groups have now changed). Because host groups have created new process groups, any custom settings configurations for the old process groups and services will need to be re-done for the new process groups.

I hope this helps!

Kind regards,
Joshua P.

[larry_roberts]

This is good information! Thank you. We have stayed clear from host groups because it is still not GA and really we were waiting on that. Also, it is not universal and we still have some Solaris hosts.

[Julius_Loman]

There are situations that are not solvable without host groups at the moment. Well maybe they are but only with a significant manual effort by reconfiguration of monitored processes.

I definitely agree with the idea to setup host groups before you do any other customization. Setting up host groups after configuration may lead to unexpected results.

Regarding Solaris - I don't think host groups will ever come to this platform. (probably applies to all other PaaS agent versions as well)

[joshua_dtrace]

You're welcome, Larry R.! Glad to help! 🙂

While it's not GA, Early Adopter Release of Host Groups means that it's a fully supported functionality of our solution (meaning Dynatrace ONE Live Chat and Dynatrace Support will be able to help you with any concerns you have).

For your Kubernetes questions I was able to find this information:

• If you are using the OneAgent Operator deployment method, you can configure the HOST_GROUP parameter in the "args" section of the relevant custom resource .yaml file (described here in Step 3 and 4 in the "Custom resource snippet" dropdown).

And for Solaris:

• We won't have the capability to use HOST_GROUP as a parameter for Solaris as our OneAgent is not "full-stack" for that platform. According to our public documentation's OneAgent platform and capability support matrix, it does not appear that any of the features at the bottom which we are pre-requisites for our "full-stack" moniker are planned. I'm not privy to any information that would say otherwise, though if other PMs are reading this message, please feel free to correct me! 🙂

Kind regards,
Joshua P.

[larry_roberts]

All really great info guys. We came into Dynatrace I believe at an odd time when it comes to host groups. I believe that was in the early stages so this was not a consideration at the time of initial deployment.

Thankfully we don't have what I would consider a huge deployment yet so I don't think it will be too painful. Sounds like my best approach now with getting things converted over will be to do it one host group at a time. Do one, give it burn in time so I can see what changes come out of it before moving on to the next one.

Solaris I am just going to ignore as we are actively moving everything left over to Linux so I am not too worried about that anymore. At the time we went with Dynatrace, it was still unclear how fast a migration from Solaris was going to be. Today that picture is much more clear.

I think I am just going to pick one of our smaller groups to start with. Then I can see first hand what sorts of things change and exactly what needs to be addressed. This was my biggest fear that once adding them it would turn things upside down. Kinda makes me wonder how some of the customers with really large Dynatrace deployments made the change to using host groups.

[joshua_dtrace]

Understood! Sounds like a good plan from my end.

If you run into any more questions regarding Host Groups and want assistance ASAP, please pop in to Live Chat and we'll be happy to help you out!

Kind regards,
Joshua P.