[BUG] ddclient stuck in "curl could not connect to X" loop #730

[kilrau]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

Cross posting this here as ddclient team suggests this could be related to the docker container. Original issue: ddclient/ddclient#730. When a dns resolution of a dyndns endpoint fails, ddclient gets stuck in a "curl could not connect to X and doesn't exit when dyndns endpoint is reachable again. Only fix is to restart the container.

Expected Behavior

Dyndns endpoint is reachable, resolution works.

Steps To Reproduce

1. run this image updating to an e.g. namecheap dyndns endpoint
2. bring endpoint offline when ddclient is trying to resolve
3. watch infinity loop

Environment

- OS: Ubuntu 20.04. LTS
- How docker service was installed: https://docs.docker.com/engine/install/ubuntu/#install-using-the-repository

CPU architecture

x86-64

Docker creation

docker-compose.yml

services:
  ddclient-mydomain.com:
    image: lscr.io/linuxserver/ddclient:latest
    container_name: ddclient-mydomain.com
    environment:
      - PUID=1001
      - PGID=1001
      - TZ=Europe/Berlin
    volumes:
      - /path/to/config
    restart: unless-stopped

Container logs

Infinity loop of:

WARNING:  CURL error (6) Couldn't resolve host. The given remote host was not resolved.
WARNING:  curl cannot connect to https://dynamicdns.park-your-domain.com using IPv0
WARNING:  found neither IPv4 nor IPv6 address
WARNING:  Could not determine an IP for @
WARNING:  CURL error (6) Couldn't resolve host. The given remote host was not resolved.
WARNING:  curl cannot connect to https://dynamicdns.park-your-domain.com using IPv0
WARNING:  found neither IPv4 nor IPv6 address
WARNING:  Could not determine an IP for @

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[Roxedus]

I agree with the upstream issue, this is a networking issue in your docker stack. Not the application or the container image.

[kilrau]

so why did it work immediately when I restarted the container?

[Roxedus]

Intermediate networking issues occur. hard to say without more data. We don't explicitly handle dns or curl in the container.