20.6 交付并观察 HA 集群

Pigsty declaration and operator entry
PostgreSQL/Patroni native evidence

pg-test-1  10.10.10.11  declared primary
pg-test-2  10.10.10.12  declared replica
pg-test-3  10.10.10.13  declared replica + offline intent

pg-test:
  vars:
    pg_cluster: pg-test
    pg_version: 18
    pg_conf: crit.yml
  hosts:
    10.10.10.11:
      pg_seq: 1
      pg_role: primary
    10.10.10.12:
      pg_seq: 2
      pg_role: replica
    10.10.10.13:
      pg_seq: 3
      pg_role: offline

desired membership
stable instance identity
initial placement intent
parameter template
service definition

live PostgreSQL role
replication caught up
DCS authority
client routing
failure-domain independence
RPO/RTO

local Patroni config
  member-specific bootstrap/connectivity/watchdog/DCS endpoint

dynamic Patroni config in DCS
  ttl, loop_wait, sync mode, failover lag, PostgreSQL parameters

each member local:
  scope/member_name/version
  dcs kind and endpoint count
  watchdog mode
  REST/PostgreSQL connect address

cluster dynamic:
  ttl/loop/retry
  maximum_lag_on_failover
  sync modes
  pause/failsafe
  use_pg_rewind/use_slots

primary :5433
  read-write -> current primary -> default target usually PgBouncer

replica :5434
  read-only -> eligible replicas; policy can define fallbacks

default :5436
  admin/direct -> current primary PostgreSQL

offline :5438
  offline/OLAP placement

port
destination: pgbouncer/postgres
Patroni health endpoint
member selector
backup selector

client
  -> member/VIP/DNS :5433
      -> HAProxy
          -> backend health on Patroni :8008 /primary
              -> current primary PgBouncer :6432
                  -> PostgreSQL :5432

name/port/protocol
write/read semantics
pooling mode
TLS identity
health source
fallback selectors
timeouts
max connections/queue
DNS/VIP provider
owner

failure scope
acknowledgement class
FIRST/ANY set
candidate tags
strict/degrade behavior
placement
latency budget
test plan
rollback

pig pt list pg-test
pig pt config show
pig pt status

patronictl -c /etc/patroni/patroni.yml \
  list pg-test --format=json

patronictl -c /etc/patroni/patroni.yml \
  show-config pg-test

cluster/member identity
one leader
replica state
timeline
lag
pause
dynamic policy

SELECT pg_is_in_recovery(),
       current_setting('cluster_name'),
       current_setting('server_version_num');

one false  -> current primary
two true   -> standbys
cluster_name = pg-test
server major = 18

SELECT application_name, client_addr, state, sync_state,
       sent_lsn, flush_lsn, replay_lsn
FROM pg_stat_replication;

SELECT status, sender_host, sender_port,
       written_lsn, flushed_lsn, latest_end_lsn
FROM pg_stat_wal_receiver;

application names = exact nonleaders
client address = declared address
receiver upstream = exact current primary
state = streaming

SELECT system_identifier FROM pg_control_system();
SELECT timeline_id FROM pg_control_checkpoint();

same system identifier all members/all phases
one Patroni timeline per phase
primary current WAL timeline equals Patroni
timeline advances on promotion
checkpoint timeline is named and interpreted correctly

SELECT slot_name, active, restart_lsn, wal_status, safe_wal_size
FROM pg_replication_slots;

pg_wal filesystem
archive success/failure
WAL generation rate

psql "service=pg36-ch20" -X -w \
  -c "select pg_is_in_recovery(), inet_server_addr();"

status=private-service-created
secret_values_exported=0

connect
read-write attribute
server role
transaction
reconnect through transition

Patroni member/leader changes
WAL generation/send/receive/replay
replication lag
slots/WAL retention
HAProxy backend state and sessions
PgBouncer connections/wait
PostgreSQL transaction/lock/error
host CPU/memory/disk/network
DCS latency/health

SSH -F /dev/null
BatchMode=yes
allowlisted local config
no arbitrary Patroni tags
no credential output
structured JSON
source SHA-256

pig pt list pg-test
pig pt switchover --plan
pig pt switchover -l pg-test-1 -c pg-test-2
pig pt failover -c pg-test-2 --plan
pig pt config show
pig pt log -f

pig pt reinit pg-test-2 --plan

executor=patronictl
config=/etc/patroni/patroni.yml
cluster=pg-test
leader/candidate explicit

task.sh all
  -> capture
  -> switchover
  -> verify

capture   read-only current snapshot
verify    validate retained evidence
review    provenance + interpretation
all       verify + review only

drill:switchover
  separately guarded L2 action

reset:fixture
  separately guarded destructive action

PG36_CH20_TARGET=pg36-l2-vagrant/pg-test
PG36_CH20_NONPRODUCTION=true
PG36_CH20_PRODUCTION_DATA=false
PG36_CH20_PRODUCTION_TRAFFIC=false
PG36_CH20_CONFIRM=SWITCH_CH20_PG_TEST_1_TO_2_AND_BACK
new empty evidence directory
private mode-0600 chapter-19 inventory

same exact target/confirmation/authority
service file mode=0600 and not symlink
host/port/database/user/service attributes match contract
output directory empty

chapter 19 all -> pass
private service generation
chapter 20 drill
positive + ten negative validations
chapter 19 all -> pass
chapter 20 review
temporary secret cleanup

pg-test-1 returned as unique primary
two replicas stream
host/service baseline not drifted
production gate remains pending

drill-run.json
migration-effort.json

claim production from sandbox
switch unreviewed candidate
ignore action failure
foreign system identifier
two leaders
no timeline advance
old primary not rejoined
acknowledged token lost
unknown outcome unreconciled
write gap above objective

export PG36_EVIDENCE_DIR=/private/evidence/ch20-formal
static/labs/ch20/task.sh all

inventory declares; live planes prove
service abstracts role, not failure semantics
Pigsty wrappers map to Patroni/PostgreSQL primitives
exact release boundaries matter
all must be safe to repeat
mutation, validation, and reset need separate authority
negative tests protect interpretation