Record MQTT topics to a MikroTik router's SSD

Mon, 02 Nov 2026 00:00:00 +0000

This runs mosquitto_sub in a RouterOS 7.24 container and appends every message on a set of MQTT topics to a file on the router's SSD, one file per UTC day, with a timestamp on each line.

Tested on: a MikroTik router with RouterOS 7.24, the container package and a USB SSD (usb1-part1), image eclipse-mosquitto:2.1.2-alpine pulled from Docker Hub, broker in another container on the same container bridge (2026-11-02). The stop-signal behaviour of run.sh was re-checked in Docker 29.9.2 on Fedora 44 the same day.
Not verified: the rollback; the day switch of the file name (the recorder has run for less than a day); this exact order (my first deploy named another container's envlist, and I moved the running container to mqttrec later the same day); and the commands of steps 1, 3 and 6 as written here: my notes record what each step did, not these exact lines.
Needs: a container bridge with a gateway address on the router and an MQTT broker reachable from it; the router's container registry set to Docker Hub; a read-only MQTT user; SSH and SCP to the router; an external disk with free space.
Time: 20 min plus the image pull.
Risk: low. The container only opens an outbound MQTT connection and writes to one directory. Nothing rotates or deletes the files: about 3.5 to 5 MB a day, so a large SSD lasts decades, a small USB stick does not. Rollback removes one container, one mount, one envlist, one bridge port and one veth.

Before you start#

Placeholders used below:

Placeholder	Meaning (mine)
`<ROUTER>`	SSH `user@address` of the router, plus your own `-i <KEY>` options
`<DISK>`	the external disk (`usb1-part1`)
`<CT_BRIDGE>`	the bridge your containers' veths are ports of (`bridge-containers`)
`<CT_ADDR>` / `<CT_GW>`	a free address on that bridge for the recorder, and the bridge's gateway (`172.17.0.5`, `172.17.0.1`)
`<BROKER_IP>`	the broker's address as seen from the container bridge (`172.17.0.3`)
`<MQTT_USER>` / `<MQTT_PASSWORD>`	the read-only MQTT login the recorder uses

The registry is Docker Hub. remote-image pulls from the registry set in /container/config, and MikroTik's documented default is https://lscr.io/. Check registry-url in ssh <ROUTER> '/container/config/print'; if it isn't Docker Hub, set it as MikroTik's page shows: /container/config/set registry-url=https://registry-1.docker.io.
The broker accepts the read-only user and lets it subscribe to the topics you put into run.sh in step 2.
Backup: take a config export before step 1 (/export file=<DISK>/backups/<NAME>) and copy it off the router.

Logging on tsvinc

Record MQTT topics to a MikroTik router's SSD

Before you start#