BUG REPORT INFORMATION

Description

If I run a one-off container based on a service definition using the run subcommand and override the entrypoint, Compose 2.6.0 fails to clear the default command (default arguments to the default entrypoint) as well. As far as I can think of, every other Docker interface to override the entrypoint also clears CMD:

• docker-compose run in v1
• the run subcommand of Docker itself:

Note: Passing --entrypoint will clear out any default command set on the image (i.e. any CMD instruction in the Dockerfile used to build it).

• Compose YAML files according to the Compose spec:

Compose implementations MUST clear out any default command on the Docker image - both ENTRYPOINT and CMD instruction in the Dockerfile - when entrypoint is configured by a Compose file.

• Older versions of the Compose YAML file format:

Note: Setting entrypoint both overrides any default entrypoint set on the service’s image with the ENTRYPOINT Dockerfile instruction, and clears out any default command on the image - meaning that if there’s a CMD instruction in the Dockerfile, it is ignored.

Steps to reproduce the issue:

1. Define a service with both an entrypoint and a default command to pass to it, e.g.

services:
  database:
    image: mysql:8.0
    command: ["--help"]

2. Run a docker compose run command that overrides the entrypoint with a different executable, e.g.

$ docker compose run --rm --entrypoint=ls database

Describe the results you received:

The new entrypoint, ls, responds as if it was passed the default arguments intended for the original entrypoint, namely the --help, flag, and prints a usage message.`

Describe the results you expected:

I expected the new entrypoint, ls, to be run without arguments and list the files in the container's working directory.

Additional information you deem important (e.g. issue happens only occasionally):

None.

Output of docker compose version:

Docker Compose version v2.6.0

Output of docker info:

Snippet:

Client:
 Context:    default
 Debug Mode: false
 Plugins
  app: Docker App (Docker Inc., v0.9.1-beta3)
  buildx: Docker Buildx (Docker Inc., v0.8.2-docker)
  compose: Docker Compose (Docker Inc., v2.6.0)
  scan: Docker Scan (Docker Inc., v0.17.0)

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 10
 Server Version: 20.10.17
[...]
 Kernel Version: 5.4.0-121-generic
 Operating System: Linux Mint 20.2
 OSType: linux
 Architecture: x86_64
[...]

Additional environment details:

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