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compose-files/postgresql/cutover/postgresql-ha-staging.yaml
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# ─────────────────────────────────────────────────────────────────────────
# postgresql/cutover/postgresql-ha-staging.yaml — ADR-0001 Phase 3, Stage 2
#
# Deployed by postgres-ha-cutover.sh as a SEPARATE stack:
# docker stack deploy -c postgresql/cutover/postgresql-ha-staging.yaml postgresqlha
#
# ⚠️ NEVER deploy this via stack-deploy.sh or under the "postgresql" stack
# name. It lives in cutover/ (a subdirectory) deliberately:
# stack-deploy.sh folder mode merges all *.yml/yaml at -maxdepth 1 of
# postgresql/, and merging this into the production stack would cause
# an outage. Subdirectory files are excluded from that merge.
#
# What this stage does:
# - Joins the EXISTING postgresql_db-backend overlay (external) — the
# live single-instance stack is untouched and keeps the "postgresql"
# and "db" aliases.
# - patroni-0/patroni-1 bootstrap a NEW cluster (scope: postgres-ha) as a
# Patroni STANDBY CLUSTER continuously streaming from the live
# instance (standby_cluster, host: postgresql — resolves to the OLD
# instance during staging). This REPLACES the earlier
# CLONE_WITH_BASEBACKUP design (one-shot snapshot) — see "REVISION"
# note below for why.
# - HAProxy runs WITHOUT production aliases and WITHOUT published ports.
# It only gets those in postgresql-ha-final.yaml at promote time.
# - Superuser is PGadmin (matches the cloned data's existing superuser,
# same password secret), NOT Spilo's default "postgres".
#
# ─── REVISION (2026-08-01): switched from CLONE_WITH_BASEBACKUP to a
# Patroni "standby cluster" (continuous streaming) ───
#
# WHY: CLONE_WITH_BASEBACKUP is a ONE-SHOT snapshot — once pg_basebackup
# completes, the new cluster has ZERO further connection to the live
# database. Any write landing on production between the snapshot and the
# actual traffic cutover would be silently lost — a real risk given ~13
# active consumers and a 42GB production database. Patroni's standby_cluster
# mode (https://patroni.readthedocs.io/en/latest/standby_cluster.html)
# instead makes the new cluster's leader ("standby leader") continuously
# stream from the remote primary indefinitely, right up until an explicit
# promotion (done by removing the standby_cluster key from DCS config —
# there is no dedicated patronictl subcommand for this) — closing the gap
# to near-zero. Fully validated end-to-end in the pgha-test dry run
# (2026-08-01): bootstrap, continuous live-write propagation to the far
# cascade replica in <3s, and a full promote-with-zero-data-loss cycle —
# see "ADR-0001 Dry-Run Debugging Log" note for the complete play-by-play.
#
# ⚠️ NEW PRODUCTION PREREQUISITE THIS INTRODUCES — NOT YET DONE, must
# happen before this file can actually be deployed for real: the dry run's
# "legacy" stand-in creates a genuine replication role named "standby"
# (matching PGUSER_STANDBY below) via a fresh-initdb hook script, since
# standby_cluster streaming authenticates using the cluster's real
# replication identity (PGUSER_STANDBY/PGPASSWORD_STANDBY), NOT the
# PGadmin superuser that CLONE_WITH_BASEBACKUP used. The LIVE
# `postgresql_postgresql` container has NO such hook mechanism available
# (it's long since initialized, hooks only run on fresh initdb) and does
# NOT currently have a "standby" role. This must be created manually
# against the live database before real cutover, analogous to how the
# pg_hba.conf replication rule was added manually — e.g.:
# CREATE ROLE standby WITH REPLICATION LOGIN PASSWORD '<same value as
# the postgresql_replication_password secret>';
# This is NOT part of this compose file (can't be — it's a one-time SQL
# statement against already-running production, not something a compose
# file can express) but MUST be tracked and done as an explicit manual
# step in the real Phase 3 procedure. See ADR-0001 Dry-Run Debugging Log
# note, "Not yet done" section, for status.
#
# NOTE: command: blocks use $$(...) not $(...) — Compose's own variable
# interpolation parses $( as an attempted ${VAR} reference and fails with
# "invalid interpolation format" / "you may need to escape any $ with
# another $". $$ escapes to a literal $ for the shell at runtime. This
# applies uniformly to EVERY literal $ character anywhere in a command:
# block, including inside heredocs and nested quoting — Compose scans the
# raw text before any shell/heredoc logic ever runs, so quoting context
# doesn't exempt anything from this escaping requirement. (Confirmed the
# hard way in the pgha-test dry run — this file originally had the
# unescaped $(...) bug too, before this standby_cluster rewrite.)
#
# NOTE: ETCD3_HOSTS not ETCD_HOSTS — confirmed against zalando/spilo
# configure_spilo.py: PATRONI_DCS includes both "etcd" (legacy v2 API,
# python-etcd client) and "etcd3" (v3 API, python-etcd3 client) as
# distinct DCS backends selected by env var prefix. Our etcd containers
# (v3.5.9) have the v2 API disabled by default, so ETCD_HOSTS causes
# Patroni to hit /v2 endpoints that 404. ETCD3_HOSTS selects the correct
# v3-API client.
#
# NOTE: patroni-0/patroni-1 override bootstrap.post_init via
# SPILO_CONFIGURATION (Spilo's documented, supported mechanism for
# overriding any generated Patroni config — configure_spilo.py deep-merges
# user-supplied SPILO_CONFIGURATION on top of its own generated config).
# This is needed because Spilo's own /scripts/post_init.sh hardcodes
# "ALTER VIEW ... OWNER TO postgres" with no way to parameterize that role
# name via env vars. Since our superuser is PGUSER_SUPERUSER=PGadmin, there
# is no role literally named "postgres" in the cloned data, so Spilo's
# unmodified script fails with 'ERROR: role "postgres" does not exist'.
# The override points bootstrap.post_init at our own wrapper script
# instead, which creates a harmless, idempotent "postgres" role (WITH
# SUPERUSER NOLOGIN — SUPERUSER is required because Spilo's own
# _zmon_schema.dump does "SET ROLE TO postgres; CREATE EXTENSION
# plpython3u", which needs real superuser privileges, not just role
# existence; NOLOGIN means it can never be used to establish a real
# connection, so this carries no security exposure), then execs Spilo's
# real, UNMODIFIED post_init.sh with all original arguments passed through
# — Zalando's script itself is never patched or forked. Both fixes (role
# existence + SUPERUSER) were found and validated end-to-end in the
# pgha-test dry run before being ported here — see the dry-run debugging
# note for full detail. This is CRITICAL for this file specifically since
# it streams real production data with the real PGadmin superuser.
# ─────────────────────────────────────────────────────────────────────────
version: "3.6"
services:
etcd-1:
image: quay.io/coreos/etcd:v3.5.9
hostname: etcd-1
command:
- etcd
- --name=etcd-1
- --data-dir=/etcd-data
- --initial-advertise-peer-urls=http://etcd-1:2380
- --listen-peer-urls=http://0.0.0.0:2380
- --listen-client-urls=http://0.0.0.0:2379
- --advertise-client-urls=http://etcd-1:2379
- --initial-cluster=etcd-1=http://etcd-1:2380,etcd-2=http://etcd-2:2380,etcd-3=http://etcd-3:2380
- --initial-cluster-state=new
- --initial-cluster-token=postgresql-ha-etcd
volumes:
- /volume1/docker/PostgreSQL/etcd-1-data:/etcd-data
networks:
- postgresql_db-backend
deploy:
placement:
constraints:
- node.hostname == docker-1
etcd-2:
image: quay.io/coreos/etcd:v3.5.9
hostname: etcd-2
command:
- etcd
- --name=etcd-2
- --data-dir=/etcd-data
- --initial-advertise-peer-urls=http://etcd-2:2380
- --listen-peer-urls=http://0.0.0.0:2380
- --listen-client-urls=http://0.0.0.0:2379
- --advertise-client-urls=http://etcd-2:2379
- --initial-cluster=etcd-1=http://etcd-1:2380,etcd-2=http://etcd-2:2380,etcd-3=http://etcd-3:2380
- --initial-cluster-state=new
- --initial-cluster-token=postgresql-ha-etcd
volumes:
- /volume1/docker/PostgreSQL/etcd-2-data:/etcd-data
networks:
- postgresql_db-backend
deploy:
placement:
constraints:
- node.hostname == docker-2
etcd-3:
image: quay.io/coreos/etcd:v3.5.9
hostname: etcd-3
command:
- etcd
- --name=etcd-3
- --data-dir=/etcd-data
- --initial-advertise-peer-urls=http://etcd-3:2380
- --listen-peer-urls=http://0.0.0.0:2380
- --listen-client-urls=http://0.0.0.0:2379
- --advertise-client-urls=http://etcd-3:2379
- --initial-cluster=etcd-1=http://etcd-1:2380,etcd-2=http://etcd-2:2380,etcd-3=http://etcd-3:2380
- --initial-cluster-state=new
- --initial-cluster-token=postgresql-ha-etcd
volumes:
- /volume1/docker/PostgreSQL/etcd-3-data:/etcd-data
networks:
- postgresql_db-backend
deploy:
placement:
constraints:
- node.hostname == docker-3
patroni-0:
image: ghcr.io/zalando/spilo-17:4.0-p3
hostname: patroni-0
command:
- /bin/sh
- -c
- |
export PGPASSWORD_SUPERUSER="$$(cat /run/secrets/postgresql_password)"
export PGPASSWORD_STANDBY="$$(cat /run/secrets/postgresql_replication_password)"
export PATRONI_RESTAPI_PASSWORD="$$(cat /run/secrets/postgresql_patroni_password)"
mkdir -p /scripts
cat > /scripts/post_init_wrapper.sh <<'WRAP'
#!/bin/bash
set -e
psql -d "$$2" -v ON_ERROR_STOP=1 -c 'DO $$do$$ BEGIN IF NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles WHERE rolname = $$x$$postgres$$x$$) THEN CREATE ROLE postgres WITH SUPERUSER NOLOGIN; END IF; END $$do$$;'
exec /scripts/post_init.sh "$$@"
WRAP
chmod +x /scripts/post_init_wrapper.sh
exec /bin/sh /launch.sh init
environment:
SCOPE: postgres-ha
PATRONI_NAME: patroni-0
ETCD3_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
PGUSER_SUPERUSER: PGadmin
PGUSER_STANDBY: standby
PATRONI_RESTAPI_USERNAME: patroni
PGROOT: /home/postgres/pgdata/pgroot
SPILO_CONFIGURATION: |
bootstrap:
post_init: /scripts/post_init_wrapper.sh "zalandos"
dcs:
standby_cluster:
host: postgresql
port: 5432
create_replica_methods:
- basebackup_fast_xlog
secrets:
- postgresql_password
- postgresql_replication_password
- postgresql_patroni_password
volumes:
- /volume1/docker/PostgreSQL/patroni-0-data:/home/postgres/pgdata
networks:
- postgresql_db-backend
deploy:
placement:
constraints:
- node.labels.pg-role == primary
patroni-1:
image: ghcr.io/zalando/spilo-17:4.0-p3
hostname: patroni-1
command:
- /bin/sh
- -c
- |
export PGPASSWORD_SUPERUSER="$$(cat /run/secrets/postgresql_password)"
export PGPASSWORD_STANDBY="$$(cat /run/secrets/postgresql_replication_password)"
export PATRONI_RESTAPI_PASSWORD="$$(cat /run/secrets/postgresql_patroni_password)"
mkdir -p /scripts
cat > /scripts/post_init_wrapper.sh <<'WRAP'
#!/bin/bash
set -e
psql -d "$$2" -v ON_ERROR_STOP=1 -c 'DO $$do$$ BEGIN IF NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles WHERE rolname = $$x$$postgres$$x$$) THEN CREATE ROLE postgres WITH SUPERUSER NOLOGIN; END IF; END $$do$$;'
exec /scripts/post_init.sh "$$@"
WRAP
chmod +x /scripts/post_init_wrapper.sh
exec /bin/sh /launch.sh init
environment:
SCOPE: postgres-ha
PATRONI_NAME: patroni-1
ETCD3_HOSTS: '"etcd-1:2379","etcd-2:2379","etcd-3:2379"'
PGUSER_SUPERUSER: PGadmin
PGUSER_STANDBY: standby
PATRONI_RESTAPI_USERNAME: patroni
PGROOT: /home/postgres/pgdata/pgroot
SPILO_CONFIGURATION: |
bootstrap:
post_init: /scripts/post_init_wrapper.sh "zalandos"
dcs:
standby_cluster:
host: postgresql
port: 5432
create_replica_methods:
- basebackup_fast_xlog
secrets:
- postgresql_password
- postgresql_replication_password
- postgresql_patroni_password
volumes:
- /volume1/docker/PostgreSQL/patroni-1-data:/home/postgres/pgdata
networks:
- postgresql_db-backend
deploy:
placement:
constraints:
- node.labels.pg-role == replica
# Staging HAProxy: NO production aliases, NO published ports. Reachable
# in-network as "haproxy" for pre-promote testing only.
haproxy:
image: haproxy:2.9-alpine
hostname: haproxy
volumes:
- /volume1/docker/compose-files/postgresql/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg:ro
networks:
- postgresql_db-backend
deploy:
mode: global
networks:
postgresql_db-backend:
external: true
secrets:
postgresql_password:
external: true
postgresql_replication_password:
external: true
postgresql_patroni_password:
external: true