Octal format for `mode: "0o400"` does not work for docker compose v2.26.1-desktop.1

[mjl-p4]

Is this a docs issue?

• My issue is about the documentation content or website

Type of issue

Information is incorrect

Description

The example at https://docs.docker.com/compose/how-tos/use-secrets/ uses mode: "0o400" to set the mode of a /run/secrets/foo file, but on Fedora 41, docker compose v2.26.1-desktop.1 hates this syntax:

$ source .env && docker compose -p $COMPOSE_PROJECT_NAME -f docker-compose-dev.yml up
error while interpolating services.repoman.secrets.[].mode: failed to cast to expected type: strconv.Atoi: parsing "0o400": invalid syntax

Of course the goal is to put an octal number here, but it's not clear to me that strconv.Atoi("0400") is doing the right thing either?

Location

https://docs.docker.com/reference/compose-file/services/

Suggestion

No response

[b-]

I'm having a similar problem with this syntax. I get a different error on Docker Compose version v2.35.1, though -- I guess they switched from strconv.Atoi() to strconv.ParseInt():

decoding failed due to the following error(s):

error decoding 'services[op-connect-api].secrets[0].mode': strconv.ParseInt: parsing "0o400": invalid syntax

The issue is actually the quotes -- since file modes are in octal format, and Yaml natively supports octal values, Docker Compose expects file modes to be integers, not strings. So the answer is removing the quotes.

[mjl-p4]

Removing the quotes works! Thanks, @b- !

[b-]

Removing the quotes works! Thanks, @b- !

(if I may humbly ask, please reopen this issue, to track the bug in the documentation)

[mjl-p4]

Reopened.