Allow defining position of sidecar in init containers

[neo42JBR]

Hey there,

I am in need to add a CI pod to our netbird network to access our git repositiories.
To achive my goal, my plan is to use a sidecar profile resource.

The pod that needs updating looks like this:

initContainers:
- git-cloner
containers:
- worker

When the sidecar profile is added, it will result in:

initContainers:
- git-cloner
- netbird
containers:
- worker

This ordering would require a successful clone of the repo before the netbird connection is established.

My immediate idea for resolving this issue would be an optional setting, that allows specifying if the container is prepended or appended to the init container list.

[phillebaba]

I wonder what the current merging behavior is? It must be either random or prepend. It makes more sense that the default behavior is append so that the netbird client container is always the first to start. I have trouble seeing any major use case for the opposite. Would that work for you?

[neo42JBR]

Wouldn' that require the container to be prepended as the list ist started top to bottom?
If we mean the same thing, that would work for me.

It would follow the logic of the kubelet to provide storage and network before the first container starts. One could argue netbird to be part of the network stack.

[phillebaba]

What I mean is that we make sure that the NetBird container is the first in the init container list. Ensuring that it starts first, and any other user defined container starts after that.

[neo42JBR]

Just wanted to make sure we are on the same page. For my use-case this would be good.

As you mentioned I dont see any immediate other use-case for it to start later.
My proposal for a setting was solely to not change the current behaviour.