Add opt-in control-plane registration to server/supervisor: once Agones
Ready succeeds, POST /v1/servers/{id}/register (assignment_ready=false)
using a workload token read fresh from disk each call -- matching how a
Kubernetes projected service account token is rotated in place by
kubelet, unlike a cached/env-var secret. ControlPlaneURL empty (the
default) is a total no-op, so direct/Compose mode and allocated-without-
control-plane mode are both byte-for-byte unaffected; New() rejects a
half-configured registration (URL set without token path/server/match/
digest) rather than silently skipping it.
ServerID/MatchID/ImageDigest are read from env vars named by CLI flags
(--server-id-env, --match-id-env, --image-digest-env), matching the
existing --drain-token-env convention in this same binary, rather than
parsed out of the Agones SDK's own GameServer JSON -- that shape isn't
independently verifiable from here, whereas the Kubernetes Downward API
(fieldRef: metadata.name) populating an env var is a standard, safe
pattern already used elsewhere in this codebase for exactly this class
of secret.
A registration failure now kills the child (matching the existing
waitReady failure path) rather than leaving Agones-Ready-but-
control-plane-unregistered process running -- a real gap the second new
test (TestControlPlaneRegistrationFailureKillsChildRatherThanRunningUnregistered)
had to be corrected to actually exercise: its first draft omitted
ReadyURL and was failing at waitReady, before ever reaching the code
path it claimed to test.
Josh Creek