add automated postgres upgrade migrations

.drone.yml

@@ -18,6 +18,7 @@ steps:
       STACK_NAME: pretix
       LETS_ENCRYPT_ENV: production
       CRON_ENTRYPOINT_VERSION: v1
+      DB_ENTRYPOINT_VERSION: v1
       SECRET_DB_PASSWORD_VERSION: v1
       SECRET_DJANGO_SECRET_KEY_VERSION: v1
       SECRET_SMTP_PASSWORD_VERSION: v1

abra.sh

@@ -1,5 +1,6 @@
 export PRETIX_CONFIG_VERSION=v1
 export CRON_ENTRYPOINT_VERSION=v1
+export DB_ENTRYPOINT_VERSION=v1
 export PG_BACKUP_VERSION=v1
 
 change_adminpass(){

compose.yml

@@ -49,8 +49,13 @@ services:
       - source: pg_backup
         target: /pg_backup.sh
         mode: 0555
+      - source: db_entrypoint
+        target: /docker-entrypoint.sh
+        mode: 0555
+    entrypoint:
+      /docker-entrypoint.sh
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -d $${POSTGRES_DB} -U $${POSTGRES_USER}"]
+      test: ["CMD-SHELL", "[ -f $${HEALTHCHECK_MARKER} ] || pg_isready -d $${POSTGRES_DB} -U $${POSTGRES_USER}"]
       interval: 10s
       timeout: 5s
       retries: 5
@@ -58,7 +63,7 @@ services:
       labels:
         backupbot.backup: "${ENABLE_BACKUPS:-true}"
         backupbot.backup.pre-hook: "/pg_backup.sh backup" 
-        backupbot.backup.volumes.database.path: "backup.sql"
+        backupbot.backup.volumes.postgres.path: "backup.sql"
         backupbot.restore.post-hook: '/pg_backup.sh restore'
 
   redis:
@@ -99,6 +104,10 @@ configs:
   cron_entrypoint:
     name: ${STACK_NAME}_cron_entrypoint_${CRON_ENTRYPOINT_VERSION}
     file: entrypoint.cron.sh
+  db_entrypoint:
+    name: ${STACK_NAME}_db_entrypoint_${DB_ENTRYPOINT_VERSION}
+    file: entrypoint.postgres.sh.tmpl
+    template_driver: golang
   pg_backup:
     name: ${STACK_NAME}_pg_backup_${PG_BACKUP_VERSION}
     file: pg_backup.sh

entrypoint.postgres.sh.tmpl

@@ -0,0 +1,77 @@
+#!/bin/bash
+
+set -e
+
+HEALTHCHECK_MARKER=/tmp/skip_healthcheck
+touch $HEALTHCHECK_MARKER
+MIGRATION_MARKER=$PGDATA/migration_in_progress
+OLDDATA=$PGDATA/old_data
+NEWDATA=$PGDATA/new_data
+
+install_old_postgres_debian() {
+  ## TODO: Replace with script from outline entrypoint
+  apt-get update
+  apt-get install -y git
+  git clone https://github.com/theory/pgenv.git /tmp/pgenv
+  cd /tmp/pgenv
+  export PATH="/tmp/pgenv/bin:/tmp/pgenv/pgsql/bin:$PATH"
+
+  # Install missing packages
+  apt-get install -y make curl patch gcc sudo libreadline-dev zlib1g-dev build-essential
+  pgenv check
+  LATEST_OLD_VERSION=$(pgenv available $DATA_VERSION | grep -oE "$DATA_VERSION\.[0-9]+" | tail -n 1)
+  pgenv build $LATEST_OLD_VERSION
+}
+
+install_old_postgres_alpine() {
+  apk add git
+  git clone https://github.com/theory/pgenv.git /tmp/pgenv
+  cd /tmp/pgenv
+  export PATH="/tmp/pgenv/bin:/tmp/pgenv/pgsql/bin:$PATH"
+
+  #Install Missing pagckages:
+  apk add make curl make patch gcc alpine-sdk sudo readline-dev build-base zlib-dev linux-headers
+  pgenv check
+  LATEST_OLD_VERSION=$(pgenv available $DATA_VERSION | grep -oE "$DATA_VERSION\.[0-9]+" | tail -n 1)
+  pgenv build $LATEST_OLD_VERSION
+}
+
+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"
+    if [ -f /etc/alpine-release ]; then
+      install_old_postgres_alpine
+    else
+      install_old_postgres_debian
+    fi
+    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 /tmp/pgenv/pgsql-$LATEST_OLD_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
+
+rm $HEALTHCHECK_MARKER
+
+/usr/local/bin/docker-entrypoint.sh postgres