BorgBackup not possible to IPv6-only remote host

[NickBouwhuis]

Playbook Configuration:

My vars.yml file looks like this:

backup_borg_enabled: true
backup_borg_location_repositories:
 - ssh://[email protected]/data/borg/matrix
backup_borg_storage_encryption_passphrase: "xxx"
backup_borg_ssh_key_private: |
  -----BEGIN OPENSSH PRIVATE KEY-----
  xxx
  -----END OPENSSH PRIVATE KEY-----

Matrix Server:

• OS: debian bookworm
• Architecture amd64

Problem description:
I have setup BorgBackup according to the documentation in this repo.

I have prepared a borg repo with borg init --encryption=repokey /data/borg/matrix

I have made an ssh key, configured it on my NAS and made sure I can ssh to the borg user (over IPv6)

When I configure everything and run a backup with sudo systemctl start matrix-backup-borg, I get the following result:

nick@matrix01:~$ sudo systemctl start matrix-backup-borg
Job for matrix-backup-borg.service failed because the control process exited with error code.
See "systemctl status matrix-backup-borg.service" and "journalctl -xeu matrix-backup-borg.service" for details.
nick@matrix01:~$ sudo systemctl status matrix-backup-borg
× matrix-backup-borg.service - Borg Backup
     Loaded: loaded (/etc/systemd/system/matrix-backup-borg.service; disabled; preset: enabled)
     Active: failed (Result: exit-code) since Fri 2023-08-18 19:58:34 UTC; 33s ago
TriggeredBy: ● matrix-backup-borg.timer
    Process: 47808 ExecStartPre=/usr/bin/env sh -c /usr/bin/env docker kill matrix-backup-borg 2>/dev/null || true (code=exited, status=0/SUCCESS)
    Process: 47815 ExecStartPre=/usr/bin/env sh -c /usr/bin/env docker rm matrix-backup-borg 2>/dev/null || true (code=exited, status=0/SUCCESS)
    Process: 47823 ExecStartPre=/usr/bin/env docker run --rm --name matrix-backup-borg --log-driver=none --cap-drop=ALL --read-only --user=999:1001 --network=matrix --t>
    Process: 47955 ExecStart=/usr/bin/env docker run --rm --name matrix-backup-borg --log-driver=none --cap-drop=ALL --cap-add=CAP_DAC_OVERRIDE --read-only --network=ma>
   Main PID: 47955 (code=exited, status=1/FAILURE)
        CPU: 292ms

Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: summary:
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: /etc/borgmatic.d/config.yaml: An error occurred
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: ssh://[email protected]/data/borg/matrix: Error running actions for repository
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: Remote: ssh: connect to host hostname.to.ipv6.address.of.my.nas port 22: Address not available
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: Connection closed by remote host. Is borg working on the server?
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: Command 'borg create --exclude-from /tmp/tmpa4uxejx9 --compression lz4 --one-file-system --read-special ssh://borg@h>
Aug 18 19:58:34 matrix01 matrix-backup-borg[47955]: Need some help? https://torsion.org/borgmatic/#issues
Aug 18 19:58:34 matrix01 systemd[1]: matrix-backup-borg.service: Main process exited, code=exited, status=1/FAILURE
Aug 18 19:58:34 matrix01 systemd[1]: matrix-backup-borg.service: Failed with result 'exit-code'.
Aug 18 19:58:34 matrix01 systemd[1]: Failed to start matrix-backup-borg.service - Borg Backup.

This leads me to believe that the container that runs Borg is not setup to use IPv6. What would be the correct way to tackle this?

[aine-etke]

Correct way would be sending MR to the gitlab.com/etke.cc/borgmatic ;)

[NickBouwhuis]

Hehe. Fair enough.

Any idea what could be causing this error?

[aine-etke]

Unfortunately, no. We don't have any IPv6-only hosts, so never encountered that problem

[nolith]

I have an ipv6 host as well, there is no ipv6 connectivity inside docker so every hostname that resolves to ipv6 only fail with network unreachable

[aine-etke]

Well, in that case the issue could be closed, as it is unrelated to Borg, and more about docker itself

[nolith]

Well, in that case the issue could be closed, as it is unrelated to Borg, and more about docker itself

Is not a borg problem, but it is a matrix-docker-ansible-deploy problem.

In #3764 I'm listing some software in matrix-docker-ansible-deploy that does not work correctly on ipv6-only exposed homeserver.

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