why = WHY_NOT; (Posts about monitoring)

Monitoring DNS replication

Svedrin — Fri, 03 Apr 2020 12:55:34 GMT

Suppose you’re running a few DNS servers spread across multiple locations in your infrastructure, and you want to monitor DNS replication to make sure they’re all on the same page. Here’s an approach on how to do that using Prometheus and a bit of scripting.

Processing Prometheus alerts using NodeRED

Svedrin — Tue, 11 Dec 2018 18:51:52 GMT

I’m currently building some home automation stuff using NodeRED. One of the things I need to do is trigger home automation actions from Prometheus: I’m monitoring our Solar panels using it, and I want the shutters to go down whenever it’s sunny outside. I have a Prometheus alert rule that tells me when that is. But how can I trigger NodeRED from there?

As an extra challenge, I wanted to see if I can actually do this without writing a single line of code. I do need a couple more nodes this way, but it works and it’s not all that complicated. Here’s how it’s done.

Systemd template for Docker containers

Svedrin — Mon, 09 Jul 2018 13:48:32 GMT

Here’s a systemd service template for running Dockerized services, for example the Prometheus Blackbox Exporter.

Prometheus quick start

Svedrin — Tue, 05 Jul 2016 13:50:00 GMT

Here's a little quick start procedure I like to use to get the Prometheus monitoring system up and running, featuring Prometheus itself, the node and SNMP exporters, separate directories for configured and discovered targets and a couple of basic alerts.

So far, I used this on Ubuntu 14.04 and Debian Jessie.

fluxmon-status-update-2015

Svedrin — Sat, 17 Oct 2015 17:49:59 GMT

I've been working on Fluxmon for quite a while now, so I thought it was time to give a little status update. I've done quite a lot of research in the meantime, upon which I can now base the conclusion that I don't know jack shit about what I'm doing.

The hardest issue is figuring out what it is that I actually want to do.

Fun with ntiles

Svedrin — Fri, 21 Aug 2015 12:53:14 GMT

In the last couple posts, I extracted quite a load of data from Fluxmon's PostgreSQL database. At the end of the day, I'd like to see whether or not the thing we're measuring looks broken. How can we get to that point?

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Calculating percentiles

Svedrin — Fri, 21 Aug 2015 09:40:49 GMT

One thing I've been wanting to do for quite some time now is calculating a confidence interval for the metrics measured by Fluxmon. I still have to figure out whether or not it's the same thing, but for starters I'd like to calculate percentiles for those values.

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Discrete Derivative Revisited: how to get dt

Svedrin — Thu, 20 Aug 2015 14:12:29 GMT

In the last post, I calculated the discrete derivative of a counter variable's measurements, and I took the short cut by dividing the value's difference — that is, dx — simply by 300 instead of calculating the correct value of dt. This obviously needs to be fixed.

Discrete Derivative over time series data using PostgreSQL

Svedrin — Sun, 16 Aug 2015 16:45:51 GMT

I use FluxMon to query statistics from the inverter hooked up to our solar collectors. One of the values the inverter spits out is today's energy production in Wh. This value is reset every day and counts up to a certain value. Fair enough, but I'd be way more interested in the derivative of that value, which would give an indication of how much power is being produced per hour or so.

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Nifty queries over time-series data using PostgreSQL

Svedrin — Sun, 16 Aug 2015 15:45:02 GMT

I'm currently looking into loads of maths stuff for Fluxmon, so I eventually reached the point where I'd like to try a few things. I've even collected quite a nice amount of data by now, so I have something to go with. But how to store and analyze it?

On the Chemnitz Linux Days, Hans-Jürgen Schönig held a talk named PostgreSQL: Daten superschnell analysieren which I had attended, so I wanted to get the data into PostgreSQL and try out some of the fancy stuff he showed. Googling for postgres time series, I stumbled upon this blog post showing a coupl'a nice things too, and since the schema used by this guy is radically simple, I just went ahead.

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