Update the rootFses to be an array instead of a map

[ivo1116]

• Read the Contributing document.

Summary

The PR makes sure the FSes are always used in a consistent way. The map was removed in favour of an array. The FSes should be stored in ascending order, ie. [ cflinuxfs3, cflinuxfs4 ]

The github issue: cloudfoundry/diego-release#983

Backward Compatibility

Breaking Change? No
No breaking changes, just making sure the fses are used in a consistent way

[ameowlia]

❓ are there any tests to show that it is now returning the rootFSes in order?

[ameowlia]

This code changes the behavior (I think) from before.

Before it looks like gardenHealthcheckRootFS was set to the first rootFSPath. Now it looks like it is being set to the last last rootFSPath.

❓ What is the intention behind this change? Is there a test change to go with it?

[ameowlia]

Hi @ivo1116 , I made two notes, please ping me on CFF slack (I am @ameowlia there as well) when you reply. Github notifications often get lost in the noise.

[ivo1116]

Hello @ameowlia,

The change does not modify the behaviour, since it was inconsistent anyway.
ie. assuming we have multiple stacks: fs3, fs4, and they are in this exact order
the previous behaviour would take the first one, but since it was taking from a map, the behaviour was inconsistent, returning on random one of the stacks

executor/initializer/initializer.go

Line 177 in 111288a

gardenHealthcheckRootFS = rootFSPath

The new implementation uses an array and thus we can rely on a consistent behaviour in terms of the positioning of the FSes. We take the last one, since we want to preserve the current ordering and to exclude the FS3 from the list of candidates for sidecar processes like healthcheck and envoy, since it does not work with the latest envoy binary.