docker(syncthing): Bug in folder usage during config update?

Support
1

Hi,

I think I’ve discovered a bug and appreciate your feedback if I’m just doing it the wrong way or it really needs a fix :slightly_smiling_face:.

2

Excerpt of docker-compose:

    user: "XXXXXXX:XXXXXX"
    read_only: true
    security_opt:
      - no-new-privileges=true
    cap_drop:
      - ALL
    cap_add:
      - XXXXXX
    restart: unless-stopped
    network_mode: XXXXXX
    volumes:
      # config, index and logs: rw
      - ./config/config.xml:/var/syncthing/config/config.xml
      - ./config/config.xml.tmp:/var/syncthing/config/config.xml.tmp
      - ./data:/var/syncthing/data
      - ./logs:/var/syncthing/logs
      # config certs: ro
      - ./config/cert.pem:/var/syncthing/config/cert.pem:ro
      - ./config/key.pem:/var/syncthing/config/key.pem:ro
      - ./config/https-cert.pem:/var/syncthing/config/https-cert.pem:ro
      - ./config/https-key.pem:/var/syncthing/config/https-key.pem:ro

(ENV vars set accordingly in Dockerfile)

I observe this in the log when pausing a folder (or applying another config change through the web UI). Syncthing itself runs and does its job fine, still.

INF Pausing device (device=XXXXX log.pkg=model)
ERR Failed to save config (error="open /var/syncthing/config/.syncthing.tmp.035343045: read-only file system" log.pkg=api)

I see syncthing used the /config/ folder instead of the /config/config.xml.tmp/ folder it created when it beforehand had full write access to /config/. That’s why I mounted the folder /config/config.xml.tmp/ additionally after switching read-only.

Expectation: syncthing writes the tmp config to /config/config.xml.tmp/….. instead of /config/.syncthing.tmp.035343045 which it currently does.

3

Why don’t you simply mount the whole config folder?

4

You can’t map a file as a volume and expect to be able to replace it like Syncthing does when saving the config.

5

I’ll do so, thanks. I was just curious if I could distinguish the mounts between ro and rw :slightly_smiling_face:.

1 Like