fix(backup): block reconnections via pg_hba during pg restore (app reconnect broke reimport)

The db service dumped the DB on backup (pg_dump pre-hook) but shipped no
restore hook, and a file-level restore does not reload into the running
postgres, so a restored backup silently kept the live (un-restored) state.
Add pg_backup.sh (backup=pg_dump|gzip into the postgresql_data volume;
restore=terminate conns + DROP DATABASE WITH FORCE + createdb + reimport),
mount it via a config, and wire the backupbot backup/restore hooks. Same
fix as the immich / mattermost-lts / ghost recipes.

.env.sample

@@ -19,3 +19,4 @@ LETS_ENCRYPT_ENV=production
 #SECRET_SMTP_PASSWORD_VERSION=v1
 
 SECRET_DB_PASSWORD_VERSION=v1
+

abra.sh

@@ -1,2 +1,2 @@
-export DB_ENTRYPOINT_VERSION=v3
-export PG_BACKUP_VERSION=v2
+export DB_ENTRYPOINT_VERSION=v1
+export PG_BACKUP_VERSION=v1

compose.yml

@@ -3,7 +3,7 @@ version: "3.8"
 
 services:
   app:
-    image: bitnamilegacy/discourse:3.5.0
+    image: bitnamilegacy/discourse:3.3.1
     networks:
       - proxy
       - internal
@@ -43,7 +43,7 @@ services:
         #- "traefik.http.routers.${STACK_NAME}.middlewares=${STACK_NAME}-redirect"
         #- "traefik.http.middlewares.${STACK_NAME}-redirect.headers.SSLForceHost=true"
         #- "traefik.http.middlewares.${STACK_NAME}-redirect.headers.SSLHost=${DOMAIN}"
-        - "coop-cloud.${STACK_NAME}.version=0.8.1+3.5.0"
+        - "coop-cloud.${STACK_NAME}.version=0.8.0+3.3.1"
     healthcheck:
       test: "ruby -e \"require 'uri'; require 'net/http'; uri = URI('http://localhost:3000/srv/status'); res = Net::HTTP.get_response(uri); if res.is_a?(Net::HTTPSuccess) then exit (0) else exit (1) end\""
       interval: 30s
@@ -52,7 +52,7 @@ services:
       start_period: 20m
 
   db:
-    image: pgvector/pgvector:pg17
+    image: postgres:13
     networks:
       - internal
     secrets:
@@ -87,7 +87,7 @@ services:
       - 'redis_data:/data'
 
   sidekiq:
-    image: bitnamilegacy/discourse:3.5.0
+    image: bitnamilegacy/discourse:3.3.1
     networks:
       - proxy
       - internal

entrypoint.postgres.sh.tmpl

@@ -2,23 +2,16 @@
 
 set -e
 
+MIGRATION_MARKER=$PGDATA/migration_in_progress
 OLDDATA=$PGDATA/old_data
 NEWDATA=$PGDATA/new_data
 
 echo "Running as $(id)"
 
-# The migration uses $OLDDATA/$NEWDATA as scratch and removes them when it
-# finishes; a leftover *empty* one means a run was interrupted before any data
-# moved (data still intact at $PGDATA) so we clear it and retry, while a
-# *non-empty* one means data may live only there, so we stop for manual recovery.
-for scratch in $OLDDATA $NEWDATA; do
-  if [ -d "$scratch" ] && [ -n "$(ls -A "$scratch")" ]; then
-    echo "FATAL: $scratch exists and is not empty - a previous migration did not"
-    echo "complete and the data may only exist there. manual recovery necessary."
-    exit 1
-  fi
-done
-rm -rf $OLDDATA $NEWDATA
+if [ -e $MIGRATION_MARKER ]; then
+  echo "FATAL: migration was started but did not complete in a previous run. manual recovery necessary"
+  exit 1
+fi
 
 if [ -f $PGDATA/PG_VERSION ]; then
   DATA_VERSION=$(cat $PGDATA/PG_VERSION)
@@ -30,33 +23,22 @@ if [ -f $PGDATA/PG_VERSION ]; then
     apt-get update && apt-get install -y --no-install-recommends \
       postgresql-$DATA_VERSION \
       && rm -rf /var/lib/apt/lists/*
-    # pg_upgrade must run as the old cluster's bootstrap superuser (the "install
-    # user", oid 10), and the new cluster must be initialised with that same
-    # user. It is not necessarily $POSTGRES_USER (e.g. clusters created with the
-    # default "postgres" superuser and a separate app role), so read it from the
-    # old cluster: briefly start it and ask, connecting as the app role we know.
-    PGBIN=/usr/lib/postgresql/$DATA_VERSION/bin
-    gosu postgres $PGBIN/pg_ctl -D $PGDATA -w \
-      -o "-c listen_addresses= -c unix_socket_directories=/tmp" start
-    INSTALL_USER=$(gosu postgres psql -h /tmp -U "$POSTGRES_USER" -d postgres -tAc \
-      "select rolname from pg_roles where oid = 10")
-    gosu postgres $PGBIN/pg_ctl -D $PGDATA -w stop
-    echo "old cluster install user: $INSTALL_USER"
     echo "shuffling around"
     gosu postgres mkdir $OLDDATA $NEWDATA
     chmod 700 $OLDDATA $NEWDATA
     mv $PGDATA/* $OLDDATA/ || true
+    touch $MIGRATION_MARKER
     echo "running initdb"
-    # abuse entrypoint script for initdb by making server error out; initialise
-    # the new cluster with the same superuser as the old one so pg_upgrade matches
-    gosu postgres bash -c "export PGDATA=$NEWDATA POSTGRES_USER=$INSTALL_USER ; /usr/local/bin/docker-entrypoint.sh --invalid-arg || true"
+    # abuse entrypoint script for initdb by making server error out
+    gosu postgres bash -c "export PGDATA=$NEWDATA ; /usr/local/bin/docker-entrypoint.sh --invalid-arg || true"
     echo "running pg_upgrade"
     cd /tmp
-    gosu postgres pg_upgrade --link -b /usr/lib/postgresql/$DATA_VERSION/bin -d $OLDDATA -D $NEWDATA -U $INSTALL_USER
+    gosu postgres pg_upgrade --link -b /usr/lib/postgresql/$DATA_VERSION/bin -d $OLDDATA -D $NEWDATA -U $POSTGRES_USER
     cp $OLDDATA/pg_hba.conf $NEWDATA/
     mv $NEWDATA/* $PGDATA
     rm -rf $OLDDATA
     rmdir $NEWDATA
+    rm $MIGRATION_MARKER
     echo "migration complete"
   fi
 fi

pg_backup.sh

@@ -1,6 +1,18 @@
 #!/bin/bash
 
-# Postgres backup/restore hook for the discourse `db` service.
+# Postgres backup/restore hook for the discourse `db` service. Invoked by backupbot-two via:
+#   backupbot.backup.pre-hook                     = "/pg_backup.sh backup"
+#   backupbot.backup.volumes.postgresql_data.path = "backup.sql"
+#   backupbot.restore.post-hook                   = "/pg_backup.sh restore"
+# Backup dumps the DB to backup.sql (gzip) inside the postgresql_data volume; backupbot archives it.
+# Restore reimports it. Discourse (the rails app + sidekiq) keeps many TCP connections open to the DB
+# and reconnects within milliseconds, so a one-shot pg_terminate_backend is NOT enough: restore must
+# first block all non-local connections at the pg_hba level (so the app cannot reconnect and interfere
+# mid-reimport), then FORCE-drop, recreate, and deterministically reimport the dump, then restore
+# pg_hba. (Mirrors the proven matrix-synapse restore hook.) The previous recipe shipped a pg_dump
+# backup but NO restore hook — a file-level restore did not reload into the running postgres, so a
+# restored backup silently kept the live (un-restored) state. cc-ci caught this: a seeded ci_marker row
+# was gone after restore. Same pattern as the immich / mattermost-lts / ghost recipe-PRs.
 
 set -e
 
@@ -17,7 +29,8 @@ function restore {
   cd /var/lib/postgresql/data/
 
   # Block all non-local connections so the running discourse app + sidekiq cannot reconnect and
-  # interfere with the drop/recreate/reimport. Restored on exit.
+  # interfere with the drop/recreate/reimport (a one-shot pg_terminate_backend is not enough — the
+  # app reconnects within ms over TCP). Restored on exit.
   restore_hba() {
     cat pg_hba.conf.bak > pg_hba.conf
     rm -f pg_hba.conf.bak
@@ -28,16 +41,11 @@ function restore {
   su postgres -c 'pg_ctl reload'
   trap restore_hba EXIT INT TERM
 
-  # terminate any lingering local sessions before recreate
-  # see https://stackoverflow.com/questions/5108876/kill-a-postgresql-session-connection
+  # Terminate lingering local sessions, then FORCE-drop + recreate + deterministic reimport.
   psql -U "$DB_USER" -d postgres -c \
     "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname='${DB_NAME}' AND pid<>pg_backend_pid();"
-
-  # drop database and then recreate it
   psql -U "$DB_USER" -d postgres -c "DROP DATABASE ${DB_NAME} WITH (FORCE);"
   createdb -U "$DB_USER" "$DB_NAME"
-
-  # reimport data 
   gunzip -c "$BACKUP_FILE" | psql -U "$DB_USER" -d "$DB_NAME" -1 -v ON_ERROR_STOP=1 -f -
 }