use postgres 15 and add entrypoint.sh for pg_upgrade

abra.sh

@@ -1,4 +1,5 @@
 export APP_ENTRYPOINT_VERSION=v6
+export DB_ENTRYPOINT_VERSION=v1
 
 migrate() {
 	export DATABASE_PASSWORD=$(cat /run/secrets/db_password)

compose.yml

@@ -55,17 +55,22 @@ services:
       - backend
 
   db:
-    image: postgres:11
+    image: postgres:15.3
     networks:
       - backend
     secrets:
       - db_password
+    configs:
+      - source: db_entrypoint
+        target: /docker-entrypoint.sh
+        mode: 0555
     environment:
       POSTGRES_DB: outline
       POSTGRES_PASSWORD_FILE: /run/secrets/db_password
       POSTGRES_USER: outline
     volumes:
       - "postgres_data:/var/lib/postgresql/data"
+    entrypoint: /docker-entrypoint.sh
     deploy:
       labels:
         backupbot.backup: "true"
@@ -100,3 +105,7 @@ configs:
     name: ${STACK_NAME}_app_entrypoint_${APP_ENTRYPOINT_VERSION}
     file: entrypoint.sh.tmpl
     template_driver: golang
+  db_entrypoint:
+    name: ${STACK_NAME}_db_entrypoint_${DB_ENTRYPOINT_VERSION}
+    file: entrypoint.postgres.sh.tmpl
+    template_driver: golang

entrypoint.postgres.sh.tmpl

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+MIGRATION_MARKER=$PGDATA/migration_in_progress
+OLDDATA=$PGDATA/old_data
+NEWDATA=$PGDATA/new_data
+
+if [ -e $MIGRATION_MARKER ]; then
+  echo "FATAL: previous migration not completed. manual restore necessary"
+  exit 1
+fi
+
+DATA_VERSION=$(cat $PGDATA/PG_VERSION)
+
+if [ -n "$DATA_VERSION" -a "$PG_MAJOR" != "$DATA_VERSION" ]; then
+  echo "postgres data version $DATA_VERSION found, but need $PG_MAJOR. Starting migration"
+  echo "Installing postgres $DATA_VERSION"
+  sed -i "s/$/ $DATA_VERSION/" /etc/apt/sources.list.d/pgdg.list
+  apt-get update && apt-get install -y --no-install-recommends \
+    postgresql-$DATA_VERSION \
+    && rm -rf /var/lib/apt/lists/*
+  echo "shuffling around"
+  gosu postgres mkdir $OLDDATA $NEWDATA
+  chmod 700 $OLDDATA $NEWDATA
+  mv $PGDATA/* $OLDDATA/
+  touch $MIGRATION_MARKER
+  echo "running initdb"
+  # abuse entrypoint script for initdb by making server error out
+  gosu postgres bash -c "export PGDATA=$NEWDATA ; /usr/local/bin/docker-entrypoint.sh --invalid-arg"
+  echo "running pg_upgrade"
+  cd /tmp
+  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
+
+/usr/local/bin/docker-entrypoint.sh postgres