Enhancements to the tar.gz

[danielmbrown603]

One issue and one ask.

Ask - Is there a way to reference the docker server hostname in the backup file? E.g.
BACKUP_FILENAME="backup-%Y-%m-%dT%H-%M-%S.tar.gz"
BACKUP_FILENAME="{hostname}%Y-%m-%dT%H-%M-%S.tar.gz"

Issue - I have a volume mounted for /archive in my docker-composer file like this;
- mnt/backups:/archive
When I run a backup and check the folder on the docker server, the files look like this _PNSM6~H. If I look at the /archive folder from within the container, the tar.gz is named appropriately. How can I access the tar.gz files outside of the container?

Thank you

[m90]

About your issue: I'm not sure where that is coming from. the filenames should be the same inside and outside the container. I am using the image like this for a very long time and have never seen something similar. Could I ask you for more details about your setup (compose file, OS, etc) so it might be possible for me to reproduce this?

About your request: it would probably make sense to do this in the same way that Docker itself allows you to pass (Go) templates to commands for formatting (e.g. {{ .Host }}%Y-%m-%dT%H-%M-%S.tar.gz). Then again it's pretty odd to start mixing strftime placeholders and Docker ones. Always using "Docker format" would be the most elegant option but also a breaking change. I need to think about this a little further.

[danielmbrown603]

Ubuntu 20.04.3 LTS
PERSIST= home directory for default dockerapps
Composer file - https://pastebin.com/hzxf1CV2

backup.env only has
BACKUP_FILENAME="backup-%Y-%m-%dT%H-%M-%S.tar.gz"

Thanks again!

[m90]

This looks ok on first glance. Would you mind also sharing the log output of a backup run?

[danielmbrown603]

time="2021-12-17T14:54:15-05:00" level=info msg="Created backup of /backup at /tmp/\"backup-2021-12-17T14-53-40.tar.gz\"."
time="2021-12-17T14:54:15-05:00" level=info msg="Stored copy of backup /tmp/\"backup-2021-12-17T14-53-40.tar.gz\" in local archive /archive."
time="2021-12-17T14:54:15-05:00" level=info msg="Removed tar file /tmp/\"backup-2021-12-17T14-53-40.tar.gz\"."
time="2021-12-17T14:54:15-05:00" level=info msg="Finished running backup tasks."

[m90]

It's slightly surprising your filename is quoted inside the path: /tmp/\"backup-2021-12-17T14-53-40.tar.gz\"

Could it be that your Docker version is slightly outdated and you are running into this issue: docker/compose#2854 which would mean your access keys are inadvertently quoted? You can test this easily by defining it like this:

BACKUP_FILENAME=SOMETHINGSOMETHING

instead of:

BACKUP_FILENAME="SOMETHINGSOMETHING"

See: #6 (comment)

[danielmbrown603]

Well nevermind. It was an issue with SMB and mangled names. I forgot to mention I was viewing the files over a share. Adding mangled names=no to my smb.conf seem to have fixed it. Maybe there is a trailing space somewhere.
http://zderadicka.eu/what-is-this-weird-file-name-in-my-samba-share/

[danielmbrown603]

Client: Docker Engine - Community Version: 20.10.12

I changed it too;
BACKUP_FILENAME=SOMETHINGSOMETHING

And the output became;

time="2021-12-17T15:08:47-05:00" level=info msg="Created backup of /backup at /tmp/backup-2021-12-17T15-08-14.tar.gz."
time="2021-12-17T15:08:48-05:00" level=info msg="Stored copy of backup /tmp/backup-2021-12-17T15-08-14.tar.gz in local archive /archive."
time="2021-12-17T15:08:48-05:00" level=info msg="Removed tar file /tmp/backup-2021-12-17T15-08-14.tar.gz."
time="2021-12-17T15:08:48-05:00" level=info msg="Finished running backup tasks."

That looks a lot better and I don't need the mangled names config either. Thanks!

[m90]

I guess I'll add a note about this to README considering you're not the first one to have been bitten by this. Good to know it's working for you now.

I'll circle back here once I have made up my mind about that filename template.

[m90]

Maybe a very simple solution for enabling more flexible filenames would be expanding env vars in a template just like in POSIX using https://pkg.go.dev/os#ExpandEnv

This would mean you could use

BACKUP_FILENAME="$HOST-%Y-%m-%dT%H-%M-%S.tar.gz"

in case you propagate (if you even want that) your host's $HOST into the container.

[m90]

The one thing I am still not sure about when implementing expansion of env vars is the following: it cannot be done by simply expanding vars as this is a breaking change (people might have filename patterns that accidentally get expanded with that addition).

To make it an opt-in change I see 3 possibilities:

• add a flag like BACKUP_FILENAME_EXPAND=true or similar that defaults to false
• Add a second config value for filename templates of a different name like BACKUP_FILENAME_TEMPLATE that takes precendence over BACKUP_FILENAME when set and that will use expansion
• Deprecate BACKUP_FILENAME and come up with a new variable name that is the default and will get expanded. Users that have BACKUP_FILENAME set will see a warning message about how the setting is deprecated. Right now, I can't come up with a good name for this.

Maybe the first option would be the most straight-forward and least confusing, even if slightly ugly.

[m90]

This is now released in v2.7.0