From 2d749057f9c2858b3266c442f2bdb23735f94f90 Mon Sep 17 00:00:00 2001
From: Kevin McConnell <kevin@37signals.com>
Date: Mon, 3 Aug 2026 12:16:08 +0100
Subject: [PATCH] Add ONCE backup and restore hooks

By default, ONCE pauses the application container when taking a backup.
This guarantees a consistent snapshot of the data, but for a large
installation and/or a slow destination path (like a network mount), that
pause could be a bit disruptive to live traffic.

But ONCE also support a pause-free path: if a `pre-backup` hook is
present in the container, ONCE will run that and skip the pause. So by
supplying necessary hooks, we can avoid any disruption from backups.

- `pre-backup` runs the existing script/admin/prepare-backup, which uses
  SQLite's online backup API to get a consistent snapshop.

- `post-restore` moves our snaphotted file back into place, and removes
  the orphaned sidecar files
---
 Dockerfile         |  3 +++
 hooks/post-restore | 12 ++++++++++++
 hooks/pre-backup   |  2 ++
 3 files changed, 17 insertions(+)
 create mode 100755 hooks/post-restore
 create mode 100755 hooks/pre-backup

diff --git a/Dockerfile b/Dockerfile
index 6cfbd33..b65a227 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -66,6 +66,9 @@ ENV HTTP_WRITE_TIMEOUT=300
 COPY --from=build --chown=rails:rails /usr/local/bundle /usr/local/bundle
 COPY --from=build --chown=rails:rails /rails /rails
 
+# Install ONCE backup/restore hooks
+COPY --chmod=755 hooks /hooks
+
 # Set version and revision
 ARG APP_VERSION
 ENV APP_VERSION=$APP_VERSION
diff --git a/hooks/post-restore b/hooks/post-restore
new file mode 100755
index 0000000..0b9138d
--- /dev/null
+++ b/hooks/post-restore
@@ -0,0 +1,12 @@
+#!/bin/bash
+set -euo pipefail
+
+db_name="${RAILS_ENV:-production}.sqlite3"
+snapshot="/rails/storage/backups/$db_name"
+db="/rails/storage/db/$db_name"
+
+if [ -f "$snapshot" ]; then
+  mkdir -p "$(dirname "$db")"
+  cp "$snapshot" "$db"
+  rm -f "$db-wal" "$db-shm"
+fi
diff --git a/hooks/pre-backup b/hooks/pre-backup
new file mode 100755
index 0000000..43d47f9
--- /dev/null
+++ b/hooks/pre-backup
@@ -0,0 +1,2 @@
+#!/bin/bash
+exec /rails/script/admin/prepare-backup