Add postgres major version upgrade script

abra.sh

@@ -0,0 +1 @@
+export DB_ENTRYPOINT_VERSION=v1

compose.yml

@@ -52,13 +52,18 @@ services:
     #   start_period: 1m
 
   db:
-    image: postgres:13-alpine
+    image: postgres:13
     networks:
       - internal
     secrets:
       - db_password
     volumes:
       - 'postgresql_data:/var/lib/postgresql/data'
+    configs:
+      - source: db_entrypoint
+        target: /docker-entrypoint.sh
+        mode: 0555
+    entrypoint: /docker-entrypoint.sh
     environment:
       - POSTGRES_HOST_AUTH_METHOD=trust
       - POSTGRES_USER=discourse
@@ -120,3 +125,9 @@ networks:
   proxy:
     external: true
   internal:
+
+configs:
+  db_entrypoint:
+    name: ${STACK_NAME}_db_entrypoint_${DB_ENTRYPOINT_VERSION}
+    file: entrypoint.postgres.sh.tmpl
+    template_driver: golang

entrypoint.postgres.sh.tmpl

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+set -e
+
+MIGRATION_MARKER=$PGDATA/migration_in_progress
+OLDDATA=$PGDATA/old_data
+NEWDATA=$PGDATA/new_data
+
+echo "Running as $(id)"
+
+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 $PGDATA/PG_VERSION)
+
+  if [ -n "$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/ || true
+    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 || true"
+    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
+fi
+
+/usr/local/bin/docker-entrypoint.sh postgres