topic Re: Host availability alert in Alerting

Host availability alert

Adi_10 — Fri, 02 Jan 2026 08:46:07 GMT

Hello Team,

we have some host running on our tenanat - some host are turned of and turned on automatically due to patching, manual task etc.

We need a alert to be created when the host in my management zone are turned on.

If host is turned of or shutdown - its not matter to us, but if our host turns on we need an alert for 1 specific MZ.

Re: Host availability alert

Adi_10 — Fri, 02 Jan 2026 09:01:09 GMT

is this okay to use below built in metrics for this ?

Re: Host availability alert

Julius_Loman — Fri, 02 Jan 2026 09:33:23 GMT

Yes it is. You just need to play a little bit with the metric selector and add a delta transformation so you can easily create a metric event when hosť is turned on.

Re: Host availability alert

Adi_10 — Fri, 02 Jan 2026 09:43:48 GMT

I have added a host tag filter and split by host , now the count is 1 and host number at x axis is four.

If we have created a metric event for this we need to add static threshold to 1 if the limit ?

I am confused here what to select as after selecting alert on missing data i am getting threshold number raised from 1 to 10

metric selector - builtin:host.availability.state:filter(and(or(in("dt.entity.host",entitySelector("type(host),tag(~"code:A1233"~)"))),or(eq("availability.state",up)))):splitBy("dt.entity.host"):sort(value(auto,descending)):limit(20) -

I am bit confused here what to do next ?

Re: Host availability alert

Julius_Loman — Fri, 02 Jan 2026 12:04:58 GMT

Actually, there are multiple options:

Use builtin:host.uptime - the host uptime metric and alert when uptime is below certain time. (most simple solution - but does not distinguish between reboots and OneAgents offline)
Use builtin:host.availability:splitBy("dt.entity.host"):delta metric selector and alert if value is non-zero. The delta transformation helps to filter only the spikes when the host (OneAgent) comes online.
Use the builtin:host.availability.state:filter(and(or(eq("availability.state",up)))):splitBy("dt.entity.host"):default(0,always):delta to filter just for availability up states. default transformation adds zero and delta transformation assures the final metric will show only the state changes. - this metric however does not work for paas agents (only for full stack agents).

Re: Host availability alert

Adi_10 — Thu, 08 Jan 2026 08:01:49 GMT

Used the builtin:host.availability.state:filter(and(or(eq("availability.state",up)))):splitBy("dt.entity.host"):default(0,always):delta

It's perfect metric for my host using some new entities tag - I have added this on my production env tested and verified.

thank you @JuliusLoman