feat(openbao): run three raft replicas so a node drain is not an outage #646

Merged
k.renner merged 1 commits from openbao-ha-3-replicas into master 2026-08-26 20:51:03 +00:00
2 changed files with 51 additions and 5 deletions
@@ -42,12 +42,28 @@ spec:
# the agent-injector mutating webhook is unused surface.
enabled: false
server:
# Single-node raft (not standalone/file) so we get `bao operator raft
# snapshot` as a consistent backup primitive. TLS terminates at the
# Traefik ingress; in-cluster traffic is plain HTTP.
# Raft (not standalone/file) for two reasons: `bao operator raft
# snapshot` as a consistent backup primitive, and real HA across three
# nodes. TLS terminates at the Traefik ingress; in-cluster traffic is
# plain HTTP.
ha:
enabled: true
replicas: 1
# Three, not two. Raft needs a quorum, and the quorum of two is two —
# a two-replica cluster tolerates no failures at all and would stop
# the moment one pod is sealed or rescheduled, which is worse than
# the single replica it replaced. Three tolerates one.
#
# What this buys, and what it does not: a node drain seals the replica
# on it, and raft elects a new leader from the remaining standbys
# within seconds, so the service does not go down. It does NOT remove
# the manual unseal — a sealed server can neither serve requests nor
# act as standby, so that replica stays out until someone unseals it.
#
# The consequence for rolling node maintenance is worth stating: a
# Talos upgrade drains all three nodes in turn, sealing each replica
# as it goes. Unseal each one as it comes back, or the third drain
# takes the last unsealed replica with it and quorum is lost anyway.
replicas: 3
raft:
enabled: true
setNodeId: true
@@ -65,8 +81,32 @@ spec:
cluster_address = "[::]:8201"
}
# retry_join is what makes a replica join the existing raft
# cluster instead of coming up as an isolated, uninitialized
# node. Without it, scaling the StatefulSet produces pods that
# never become peers and would each need a manual
# `bao operator raft join`.
#
# All three peers are listed on every node, including the node
# itself. That is deliberate: the stanza is a list of possible
# leaders, a node ignores its own entry, and listing all three
# means the set is identical on every replica and stays correct
# regardless of which pod currently leads.
#
# Addressed through the headless service, so each entry resolves
# to one specific pod rather than load-balancing across them.
storage "raft" {
path = "/openbao/data"
retry_join {
leader_api_addr = "http://openbao-0.openbao-internal:8200"
}
retry_join {
leader_api_addr = "http://openbao-1.openbao-internal:8200"
}
retry_join {
leader_api_addr = "http://openbao-2.openbao-internal:8200"
}
}
service_registration "kubernetes" {}
@@ -53,7 +53,13 @@ spec:
command: ["/bin/sh", "-ec"]
args:
- |
export BAO_ADDR=http://openbao.openbao.svc.cluster.local:8200
# openbao-active, not openbao: with more than one replica
# the plain service selects any pod, and a raft snapshot has
# to be taken against the leader. Standbys forward ordinary
# requests, but this is not one to leave to chance — the
# active service selects the leader by label, so the
# snapshot is always taken where it is consistent.
export BAO_ADDR=http://openbao-active.openbao.svc.cluster.local:8200
BAO_TOKEN=$(bao write -field=token auth/kubernetes/login \
role=openbao-snapshot \
jwt="$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)")