About

This repo contains a docker-compose.yml that can be used to run a Murdock worker for RIOT.

The stack will include the following containers:

• one or more container(s) using riot/murdock-worker that runs the dwq job runner
• one ssh_bridge that connects via ssh to the murdock control node and provides access to its disque and redis instances
• one redis instance acting as ccache storage backend
• a watchtower instance keeping all containers up-to-date.

Murdock Worker requirements

• at least four fast cores
• 2GB RAM per worker + 8GB RAM for ccache

Prerequisites

• docker-compose
• git
• murdock worker ssh key. ping kaspar on Matrix to get it!

Installation

• Clone this repository to a location of your choice. /srv/murdock-worker is what I use.
• Copy .env.example to .env
• Edit .env. Change at least the hostname.
• copy murdock worker ssh key to ssh/

By default, this will connect to "ci-staging", which is great for testing. Once everything is working, change .env to connect to "ci-prod".

Starting

docker-compose up -d --scale worker=N, with N being the number of concurrent jobs. Each worker will need 2GB RAM (in addition to the 8GB for the shared tmpfs for ccache). Start with half the number of physical cores.

Inside an LXC container

Running docker inside LXC comtainers works very much out of the box. E.g. on Proxmox additionally the fuse and the nesting capabilities need to be enabled and fuse-overlayfs needs to be installed. The reason is that native overlayfs cannot be used for rootless operation (or when the user launching the docker containers is only root within an LXC container namespace). Without fuse-overlayfs the VFS storage driver is used instead, which performs a deep copy of all lower layers into the upper layers. With a large number of layers, this increases storage consumption too much to be practical.

Note: Expect that fuse-overlayfs will throttle the performance of your worker quite a bit.

Also note: The metrics reported by the vector service will include RAM and CPUs available to the bare host (e.g. the Proxmox running the LXC container which runs the docker containers). To fix that, filtered versions of various /proc/ files can be provided by lxcfs that can be bind-mounted into the docker container. To do so automatically, run docker-compose -f docker-compose.yml -f docker-compose.lxc.yml up -d --scale worker=N instead of just docker-compose up -d --scale worker=N.

Configuration

If the worker is dedicated to being a Murdock worker, one worker per physical core each running 4 jobs ensures the CPUs keep busy, if enough RAM is available. If RAM is an issue, go down on workers to one per two cores, possible increasing MURDOCK_JOBS (to e.g., 8).