Awesome threading using nurseries

Svedrin

2019-07-02 15:01

I wrote about a nice threading pattern using Queues for synchronization a while ago. In the meantime, I've stumbled across Trio and I loved their concept of nurseries, which is basically a wrapper around the threads-and-queues concept that also makes sure that threads are properly joined and do not run out of control.

So today I ran across a case where I'd have to query large chunks of data from two systems in parallel, that I would then have to compare and merge into a third data set. Thus I needed a way to start two threads, return stuff from them to the main thread, and join them back together. A nursery came to mind, because it does just that. So that's what I used, and here's the code for it!

Obduction: Dive into the metastory

Svedrin

2019-04-28 16:52

I want to try something new today: Write about philosophical topics, because those have been catching my interest for a while. I'll start looking into the story of the game Obduction which has caught on to me, so I think it's worth exploring. If you haven't played the game yet, lots'a spoilers ahead, so probably go play it first.

Samba4 Read-Only DC howto

Svedrin

2019-02-06 14:42

Have you ever wanted to set up a Samba4-based Read-Only DC in a remote location? Here's how.

Speeding up Ceph recovery

Svedrin

2019-01-07 12:44

Note to self: Here's the command to speed up Ceph recovery by backfilling more than one PG at a time:

ceph tell osd.* injectargs '--osd_max_backfills 16'

Processing Prometheus alerts using NodeRED

Svedrin

2018-12-11 19:51

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.

NodeRED-based MQTT Browser

Svedrin

2018-12-02 12:59

I've recently started building stuff with NodeRED, which I really enjoy. Since I'm using MQTT as the central message bus for my system, I find myself regularly in need of knowing the current state of my MQTT topics. There are a couple of tools around, for instance MQTT.fx, which are specifically built for this purpose; but I found that MQTT.fx likes to cause high CPU load when the topic scanner thingy is running. So I'm looking for an alternative, and I thought, why not build it in NodeRED? So that's what I did.

Systemd template for Docker containers

Svedrin

2018-07-09 15:48

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

Filesystem Tuning

Svedrin

2018-07-03 22:14

A while back, I promised I'd write about file system tuning someday. Since it hasn't really happened yet, I thought I'd do it now.

Setting up Ceph FS on a Proxmox cluster

Svedrin

2018-07-02 14:12

Proxmox apparently does not yet support running CephFS, but it can be done using a bunch of manual steps. Here's how.

Getting LetsEncrypt certs non-invasively using nginx and webroot

Svedrin

2018-06-20 11:51

I finally found a nice way to get LetsEncrypt certificates integrated with websites behind a reverse-proxy.

Problem: I don't want certbot messing with my server configs, and I don't want to shut down my main web server just so I can get a cert using --standalone.