[VTAdmin] Topology Browser

[notfelineit]

Description

This PR implements the topology browser in VTAdmin. In doing so, it implements VtctldServer.GetTopologyPath. Given a path, GetTopologyPath returns the file located there in the topology server.

Web Topology Browser

Only the root topology directories are loaded at first. This has the same behavior as the topology browser in vtctld2. "Nodes" can be expanded if they are not a "terminal" node (a file node).

GetTopologyPath(path) is only called when the Expand button is clicked, and only for that specific path.

The graph is then built recursively with only the paths that have been expanded so far.

VTAdmin example:

Related Issue(s)

• [vtadmin] Topology browser #8704
• [vtadmin] View cells and cell info  #8705

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required Will be added in vtadmin web documentation efforts later

Deployment Notes

N/A

[vitess-bot]

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[ajm188]

We're also missing the cli command to correspond with the VtctldServer method

[notfelineit]

@ajm188 I wasn't sure if we wanted another cmd like the topocat one instead of this one for the command line client. I'll go ahead and add this one though.

[deepthi]

Upgrade/downgrade test failures are because we upgraded golang on release-15 to 1.18.7.
Since this PR is only adding a new vtctld API and not changing existing ones, overriding.
If they fail on the release-15.0 after back port, we'll need to investigate.

[vitess-bot]

I was unable to backport this Pull Request to the following branches: release-15.0.