https://pkg.go.dev/chromium.googlesource.com/external/github.com/luci/luci-go.git/common/tsmon/target
target package - chromium.googlesource.com/external/github.com/luci/luci-go.git/common/tsmon/target...
Package target contains information about the thing that is sending metrics - either a NetworkDevice (a machine) or a Task (a service).