CLI returns "unknown flag" error when you misspell a command and pass a flag

[dvdksn]

Description

If you try to run a nonexistent command, the CLI returns the following error:

$ docker iamges
docker: 'iamges' is not a docker command.
See 'docker --help'

But if you also pass a flag, the error focuses on the flag instead of the misspelled command name:

$ docker iamges --filter
unknown flag: --filter
See 'docker --help'.

Reproduce

$ docker iamges --filter
unknown flag: --filter
$ docker iamges -f
unknown shorthand flag: 'f' in -f

Expected behavior

It should identify that the command name is wrong, and return docker: 'COMMAND' is not a docker command.

docker version

Client:
 Cloud integration: v1.0.35-desktop+001
 Version:           24.0.5
 API version:       1.43
 Go version:        go1.20.6
 Git commit:        ced0996
 Built:             Fri Jul 21 20:32:30 2023
 OS/Arch:           darwin/arm64
 Context:           desktop-linux

Server: Docker Desktop 4.22.0 (117440)
 Engine:
  Version:          24.0.5
  API version:      1.43 (minimum version 1.12)
  Go version:       go1.20.6
  Git commit:       a61e2b4
  Built:            Fri Jul 21 20:35:38 2023
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          1.6.21
  GitCommit:        3dce8eb055cbb6872793272b4f20ed16117344f8
 runc:
  Version:          1.1.7
  GitCommit:        v1.1.7-0-g860f061
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

### docker info

```bash
$ docker info
Client:
 Version:    24.0.5
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  compose: Docker Compose (Docker Inc.)
    Version:  v2.20.2-desktop.1
    Path:     /Users/david/.docker/cli-plugins/docker-compose
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.0
    Path:     /Users/david/.docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.20
    Path:     /Users/david/.docker/cli-plugins/docker-extension
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v0.1.0-beta.6
    Path:     /Users/david/.docker/cli-plugins/docker-init
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
    Version:  0.6.0
    Path:     /Users/david/.docker/cli-plugins/docker-sbom
  scan: Docker Scan (Docker Inc.)
    Version:  v0.26.0
    Path:     /Users/david/.docker/cli-plugins/docker-scan
  scout: Command line tool for Docker Scout (Docker Inc.)
    Version:  0.20.0
    Path:     /Users/david/.docker/cli-plugins/docker-scout

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 5
 Server Version: 24.0.5
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 3dce8eb055cbb6872793272b4f20ed16117344f8
 runc version: v1.1.7-0-g860f061
 init version: de40ad0
 Security Options:
  seccomp
   Profile: unconfined
  cgroupns
 Kernel Version: 5.15.49-linuxkit-pr
 Operating System: Docker Desktop
 OSType: linux
 Architecture: aarch64
 CPUs: 5
 Total Memory: 7.667GiB
 Name: docker-desktop
 ID: 9f623071-542b-4659-9b96-3b3a0779d84a
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
 Live Restore Enabled: false

### Additional Info

_No response_

[thaJeztah]

Thanks for reporting, @dvdksn (thought I commented, but apparently forgot)

Some thoughts from the top of my head;

• wondering if this is possibly related to our CLI-plugin handling code; ISTR we have code to get (top-level) flags, so that if we call a plugin, we can pass those flags as well
• or if it's related to the code we have to conditionally show/hide commands and flags based on the environment (possibly that causes both commands and flags to be iterated up-front

But it could also be Golang or Cobra itself parsing flags before doing anything else 🤔

I guess we need to dig into "why" it parses flags before validating if it knows the command 😂

[Billy-North]

I am interested in gaining a understanding of Docker's internal workings. Based on the description this looks like a pretty reasonable first ticket to get my hands dirty. Mind if I have a go at taking on this one?

[achneerov]

It seems like there have not been any updates on Billy-North's change in a month. I will give it a try. if anyone opposes please let me know.

[ardinugrxha]

From the comment above the PR is drafting, but I want to continue to fix this, maybe this is my first contribution, can I work on this? thanks

[thaJeztah]

From the linked PR it looks like @Billy-North won't have time to work on it (https://github.com/docker/cli/pull/4568#issuecomment-1775117354) so it's probably fine to work on this if you know an alternative fix :)

Go for it, I have been too busy to look at this for the past few weeks and I am doubtful I will get a chance again for at least another few weeks. Feel free to take this one :)

[athulnair02]

Hi! I'm from the UT Austin virtualization class and as part of our open source project, I'd like to take on this issue if possible. Thanks!