Ability to specify ip or fqdn & port for HTTP server used by image-builder callback

[lknite]

I'm running image builder via a gitlab runner pipeline (which is running in kubernetes) and need to setup configuration for the callback HTTP server.

Is your feature request related to a problem? Please describe.

When a pod runs in kubernetes its using a local clusterip, that's not reachable by the outside world. Instead, it needs to be exposed via a service. The gitlab runner helm chart has the ability to expose the runner via a service. So far I do not see where I can specify the IP in image-builder. Even better, it would be nice to use an ingress and an FQDN as the FQDN would remain consistent (the gitlab runner helm chart has the ability to specify an ingress).

Describe the solution you'd like

With the gitlab runner running in a pod it can use whatever port it wants, such as port 80. There's no need to have a random port anymore. (1) Need to be able to specify the port to use so it isn't random. Now that the port is predictable it can be exposed via a service. I can take care of that and request a loadbalancer ip. (2) need to be able to specify the ip for image-builder to use in its callback. Preferably, instead of a loadbalancer ip, I'd rather use an ingress. I can take care of creating the ingress. (3) need ability to specify an ingress for image-builder to use in its callback.

If this ability doesn't already exist, it would be good to add it and configure things via environment variables. Maybe something like:

export PROXMOX_URL="https://10.0.0.21:8006/api2/json"
export PROXMOX_USERNAME="capmox@pve!capi"
export PROXMOX_CALLBACK_URL="https://image-builder.k.home.net"
export PROXMOX_CALLBACK_PORT="8080"
or
export PROXMOX_CALLBACK_URL="http://10.4.0.71:8080"
export PROXMOX_CALLBACK_PORT="8080"
or is there a toplevel this would apply to?
export IMAGEBUILDER_CALLBACK_URL="http://10.4.0.71:8080"
export IMAGEBUILDER_CALLBACK_PORT="8080"

Describe alternatives you've considered

I wouldn't be surprised if this ability already existed. I've only been trying to use image-builder for a couple weeks or so now. Mainly I've been searching through issues and documentation. I'll search more this weekend.

Additional context

Would be surprised if this feature didn't already exist. I'm guessing I just haven't found where to set it yet. If it doesn't exist then by adding this feature it would allow more folks to setup pipelines which run via kubernetes, and perhaps lead to better testing and use of image-builder by more folks.

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/kind feature

[lknite]

Use case suggesting this would be a good feature to implement:

This error seems to be reappearing with my use case of building images for proxmox. The immediate solution so that we are all using the same thing (the same version of SSH) would be to deploy via a container rather than installing all the parts on a local linux system.

[lknite]

Moving to SDK where I think the server implementation actually lives:
hashicorp/packer-plugin-sdk#264