Docker Healthcheck not running powershell commands?

Question

I am working with Docker and I have created a Dockerfile which converts my dotnet application into an image. I can then run this image and everything is working fine. I am using mcr.microsoft.com/dotnet/core/sdk:3.1-nanoserver-1809 AS base.

Now, I wanted to add the 'HealthCheck' feature of Docker. In that HealthCheck, I want to use some Powershell logic, but from the moment I use Powershell, de HealthCheck gets classified as unhealthy.

For example:

HEALTHCHECK CMD powershell -command exit 0

Results in an unhealthy container.

For example:

HEALTHCHECK CMD exit 0

Results in a healthy container

Any powershell logic I try to insert, which either returns or exits a 0, give me unhealthy containers. Right now, I'm thinking that it is the powershell just erroring whatever the logic is.

Anyone can hint at what I am doing wrong to get some powershell code login inside my Docker Healthcheck? I need this powershell code within the HealthCheck for a specific reason which is not really important.

Thanks

EDIT: I have also tried:

HEALTHCHECK CMD powershell -command return 0

and

HEALTHCHECK CMD powershell -command Write-Host 0

Both with the same result: an unhealthy container.

Can you check what the exit code is when you run that powershell command normally? — Nick ODell
– Nick ODell, Commented Aug 4, 2020 at 16:17
If I run 'exit 0' in my powershell window, it just closes my powershell window. According to the docs of Docker Healthcheck tell me: "The command’s exit status indicates the health status of the container. The possible values are: 0: success - the container is healthy and ready for use 1: unhealthy - the container is not working correctly 2: reserved - do not use this exit code " So that is why I'm trying it like this. — BramCoding
– BramCoding, Commented Aug 4, 2020 at 16:43
Could you create a script with that command in it, run it, and check the exit code? Sorry, I'm not familiar with PowerShell; I mostly write Bash. — Nick ODell
– Nick ODell, Commented Aug 4, 2020 at 16:58
I can surely do that, not so familiar myself. But what exactly do you mean with 'check the exit code'? Just run the dedicated script and see what it does? — BramCoding
– BramCoding, Commented Aug 4, 2020 at 17:16
When running the ps1 file with 'exit 0' inside, and then retrieve the $LastExitCode, I get printed a 0. When running the ps1 file with 'exit 1' inside, and then retrieve the $LastExitCode, I get printed a 1. So I see no reason why this should not work in Docker Healthcheck.. — BramCoding
– BramCoding, Commented Aug 4, 2020 at 17:40

Haroon · Accepted Answer · 2022-03-08 18:04:56Z

1

We use the following command in AWS ECS

powershell -c 'try { if ((iwr -Uri http://localhost:${CONTAINER_PORT}${HEALTHCHECK_PATH} -UseBasicParsing -DisableKeepAlive).StatusCode -eq 200) {return 0} return 1; } catch { return 1 }'

We are running windows 2016 and 20H2 containers

answered Mar 8, 2022 at 18:04

Haroon

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