Healthcheck cli arguments CMD vs CMD-SHELL

[vdemeester]

HEALTHCHECK supports CMD and CMD-SHELL as command to run. CMD-SHELL make docker prepend the healthcheck command with /bin/sh (hard-coded in the source code) — This makes it not work with some images that would not have a /bin/sh inside (like traefik or swarm or …).

This is ok, but any healthcheck cli flag (for run or service create/update) is only using CMD-SHELL. This makes it impossible to set a custom healthcheck for any image that do not provide a /bin/sh binary inside the image.

I think we should either do the other way around (i.e. using CMD by default on cli flags) or find a way to detect/specify if it should use CMD-SHELL or CMD.

Note that on docker build the use of CMD and CMD-SHELL is set depending on whether the HEALTHCHECK CMD is specified as a string or an array. We're also gonna do the same for compose (both here and in docker/compose)

/cc @thaJeztah @aanand @dnephin @talex5

[justincormack]

It should use the SHELL setting that we already have to customise the shell, not hardcoded. Probably got missed when that was switched.

[thaJeztah]

Do we have some way to set "SHELL none"? I think that's what's needed in this case (IIUC)

[talex5]

What would the syntax be for specifying a command without using a shell? JSON on the command-line? docker run --health-cmd '["/myprog"; "--foo"]'? The quoting gets a bit exteme...

[justincormack]

We don't allow specifying json on command line, yeah its not nice.

On 14 Nov 2016 11:44, "Thomas Leonard" notifications@github.com wrote:

What would the syntax be for specifying a command without using a shell?
JSON on the command-line? docker run --health-cmd '["/myprog"; "--foo"]'?
The quoting gets a bit exteme...

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[vdemeester]

@talex5 yeah that's the tricky part… I would tend to only use CMD via the command line (and let people use sh -c if they want the shell 👼).

@justincormack yep this is an orthogonal issue, but using the defined SHELL would be nice, I'll prepare a PR on that.

[vdemeester]

#28438 for using the Container configured shell instead of hardcoded ones.

[wolverian]

This doesn't look solved yet - at least I don't see how to specify on the CLI to not use a shell at all.