Compose: Undocumented flag `--interactive` for `docker compose exec`

[polarathene]

Is this a docs issue?

• My issue is about the documentation content or website

Type of issue

Information is incorrect

Description

When responding to a contribution, I noticed that the docs for docker compose exec have no -i / --interactive flag (docker exec, docker run, docker compose run all do). This was pointed out back in mid 2023 with a response that it was intentional.

While it doesn't make sense to invoke --interactive with Docker Compose given it's an implicit default, similar to how --tty has been replaced with --no-TTY (this really should accept all lowercase btw), the interactive flag does remain supported for legacy reasons (as noted at earlier linked ref).

---

Actual valid use-case however has been shown here where I advised a contributor about this hidden flag so that they could ensure a command was run non-interactively within a running container.

Not being able to do this would prevent the bash read -p command from working properly in a non-interactive context.

# Defaults: `--tty=false` + `--interactive=false`
docker exec container-name some-command

# Defaults: `--no-TTY=false` + `--interactive=true`
docker compose exec --no-TTY --interactive=false service-name some-command

Where some-command would call read -p to provide an interactive prompt otherwise, where:

• Only --no-TTY: Prompt is hidden but otherwise remains interactive.
• Only --interactive=false: Prompt appears and hangs as no input can actually be received.
• Both opt-out flags used: No prompt shown and no stdin to receive input, proper non-interactive shell.
• Neither opt-out present: Prompt appears and responds to input interactively. Blocks automation without workarounds.

Location

https://docs.docker.com/reference/cli/docker/compose/exec/

Suggestion

Document -i / --interactive is actually supported with a default of true and that it is also enabled by compose by default (similar to the equivalent docs of the --no-TTY option).

[ndeloof]

similar to how --tty has been replaced with --no-TTY

this hasn't been replaced. There's been a distinct design decision in compose vs docker/cli as exec has been introduced in compose (2016). Nowadays we would require better alignment with the CLI for consistency.

Actually, we introduced --tty later in compose to offer ability for user to select same flags for docker exec and docker compose exec, while it is a no-op for compose as a TTY is allocated by default.

[polarathene]

Yeah I just realized afterwards that --tty=false also works despite lack of documented option. That helps for consistency when documenting the caveat to users of an image when calling the command and expecting non-interactive usage 👍

[thaJeztah]

Ah, yes, these were added so that users familiar with docker exec -it ... would be able to do docker compose exec -it,;

• Proposal: add -i and -t flags on docker compose run and exec compose#9207

which would be a no-op because the defaults between compose and docker are reversed; I think we kept them hidden because the -T flag (disable TTY) already existed, and having both visible would probably be more confusing.

[thaJeztah]

with --no-TTY (this really should accept all lowercase btw)

That can probably be fixed with a NormalizeFunc; https://pkg.go.dev/github.com/spf13/pflag#FlagSet.SetNormalizeFunc

https://github.com/spf13/pflag/blob/0491e5702ad2bb108bc519a5221bcc0f52aa9564/README.md#mutating-or-normalizing-flag-names