Sync the self-hosting stack

kubernetes/02-config.yaml

@@ -18,17 +18,24 @@ data:
   #
   # A SINGLE REDIS IS A SINGLE POINT OF FAILURE FOR EVERY POD AT ONCE. This line is correct for a
   # managed Redis that fails over behind one address, and correct-but-fragile for one Deployment of
-  # one Redis. For Sentinel, comment this out and set the two below instead — see
-  # `08-redis-sentinel.yaml`, which deploys exactly that.
+  # one Redis. It is IGNORED while the two Sentinel lines below are set — and they are, because
+  # `kustomization.yaml` deploys `08-redis-sentinel.yaml`. With a managed Redis instead: remove that
+  # file from `kustomization.yaml`, delete the two lines below, and point this one at it.
+  #
+  # NEVER THIS LINE ALONE WITH 08 DEPLOYED. Its `redis` Service is headless: the name answers with
+  # all three Redis pods, and two of them are read-only replicas. Each api connection lands on one
+  # of the three, so a pod that drew a replica fails every write it makes — `READONLY You can't
+  # write against a read only replica` — while its readiness probe, which only reads, stays green.
+  # That was this file's default while the two lines below were commented out.
   REDIS_URL: "redis://redis.jarvis.svc.cluster.local:6379"
 
   # Set BOTH or neither. Sentinel needs the sentinels and the name of the primary they watch; a
   # name is refused rather than defaulted, because ioredis's own default (`mymaster`) against a
   # primary called anything else is not an error — it is a pod that never becomes ready, silently.
-  # When these are set, REDIS_URL above is ignored.
-  #
-  #REDIS_SENTINELS: "redis-sentinel-0.redis-sentinel.jarvis.svc.cluster.local:26379,redis-sentinel-1.redis-sentinel.jarvis.svc.cluster.local:26379,redis-sentinel-2.redis-sentinel.jarvis.svc.cluster.local:26379"
-  #REDIS_SENTINEL_NAME: "jarvis"
+  # When these are set, REDIS_URL above is ignored. They name what `08-redis-sentinel.yaml` deploys:
+  # its three sentinels, and `jarvis`, the primary they monitor.
+  REDIS_SENTINELS: "redis-sentinel-0.redis-sentinel.jarvis.svc.cluster.local:26379,redis-sentinel-1.redis-sentinel.jarvis.svc.cluster.local:26379,redis-sentinel-2.redis-sentinel.jarvis.svc.cluster.local:26379"
+  REDIS_SENTINEL_NAME: "jarvis"
 
   # ONE, not the two the compose files use, and getting this wrong is a security fault rather than
   # a cosmetic one.