From 67ecbb1b3e2b37c753ec1b714662b044aa80b5da Mon Sep 17 00:00:00 2001
From: Pau Rodriguez-Estivill <prodrigestivill@gmail.com>
Date: Sat, 20 Aug 2022 19:29:18 +0200
Subject: [PATCH] Implement hooks with run-parts #58

---
 README.md           | 11 +++++++++--
 alpine.Dockerfile   |  2 +-
 backup.sh           | 24 ++++++++++++++++--------
 debian.Dockerfile   |  2 +-
 hooks/00-webhook.sh | 34 ++++++++++++++++++++++++++++++++++
 5 files changed, 61 insertions(+), 12 deletions(-)
 create mode 100755 hooks/00-webhook.sh

diff --git a/README.md b/README.md
index ab7b38d..a4486d1 100644
--- a/README.md
+++ b/README.md
@@ -90,8 +90,8 @@ Most variables are the same as in the [official postgres image](https://hub.dock
 | POSTGRES_USER_FILE | Alternative to POSTGRES_USER, for usage with docker secrets. |
 | SCHEDULE | [Cron-schedule](http://godoc.org/github.com/robfig/cron#hdr-Predefined_schedules) specifying the interval between postgres backups. Defaults to `@daily`. |
 | TZ | [POSIX TZ variable](https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html) specifying the timezone used to evaluate SCHEDULE cron (example "Europe/Paris"). |
-| WEBHOOK_EXTRA_URL | Extra arguments for the webhook. |
-| WEBHOOK_URL | URL to be called after a successful backup. |
+| WEBHOOK_URL | URL to be called after an error or after a successful backup (POST with a JSON payload, check `hooks/00-webhook.sh` file for more info). Default disabled. |
+| WEBHOOK_EXTRA_ARGS | Extra arguments for the `curl` execution in the webhook (check `hooks/00-webhook.sh` file for more info). |
 
 #### Special Environment Variables
 
@@ -132,6 +132,13 @@ To do so it is using the following independent variables:
 * BACKUP_KEEP_WEEKS: will remove files from the `weekly` folder that are older than its value in weeks after a new successfull backup (remember that it starts counting from the end of each week not the beggining).
 * BACKUP_KEEP_MONTHS: will remove files from the `monthly` folder that are older than its value in months (of 31 days) after a new successfull backup (remember that it starts counting from the end of each month not the beggining).
 
+### Hooks
+
+The folder `hooks` inside the container can contain hooks/scripts to be run in differrent cases getting the exact situation as a first argument (`error`, `pre-backup` or `post-backup`).
+
+Just create an script in that folder with execution permission so that [run-parts](https://manpages.debian.org/stable/debianutils/run-parts.8.en.html) can execute it on each state change.
+
+Please, as an example take a look in the script already present there that implements the `WEBHOOK_URL` functionality.
 
 ### Manual Backups
 
diff --git a/alpine.Dockerfile b/alpine.Dockerfile
index a63c863..d3dc5db 100644
--- a/alpine.Dockerfile
+++ b/alpine.Dockerfile
@@ -31,7 +31,7 @@ ENV POSTGRES_DB="**None**" \
     WEBHOOK_URL="**None**" \
     WEBHOOK_EXTRA_ARGS=""
 
-COPY backup.sh /backup.sh
+COPY backup.sh hooks /
 
 VOLUME /backups
 
diff --git a/backup.sh b/backup.sh
index 007f4fe..ac9fd21 100755
--- a/backup.sh
+++ b/backup.sh
@@ -1,6 +1,14 @@
 #!/usr/bin/env bash
 set -Eeo pipefail
 
+HOOKS_DIR="/hooks"
+if [ -d "${HOOKS_DIR}" ]; then
+  on_error(){
+    run-parts -a "error" "${HOOKS_DIR}"
+  }
+  trap 'on_error' ERR
+fi
+
 if [ "${POSTGRES_DB}" = "**None**" -a "${POSTGRES_DB_FILE}" = "**None**" ]; then
   echo "You need to set the POSTGRES_DB or POSTGRES_DB_FILE environment variable."
   exit 1
@@ -60,6 +68,11 @@ KEEP_DAYS=${BACKUP_KEEP_DAYS}
 KEEP_WEEKS=`expr $(((${BACKUP_KEEP_WEEKS} * 7) + 1))`
 KEEP_MONTHS=`expr $(((${BACKUP_KEEP_MONTHS} * 31) + 1))`
 
+# Pre-backup hook
+if [ -d "${HOOKS_DIR}" ]; then
+  run-parts -a "pre-backup" --exit-on-error "${HOOKS_DIR}"
+fi
+
 #Initialize dirs
 mkdir -p "${BACKUP_DIR}/last/" "${BACKUP_DIR}/daily/" "${BACKUP_DIR}/weekly/" "${BACKUP_DIR}/monthly/"
 
@@ -126,12 +139,7 @@ done
 
 echo "SQL backup created successfully"
 
-if [ "${WEBHOOK_URL}" != "**None**" ]; then
-  echo "Execute post-backup webhook call to ${WEBHOOK_URL}"
-  curl --request POST \
-    --url "${WEBHOOK_URL}" \
-    --max-time 10 \
-    --retry 5 \
-    ${WEBHOOK_EXTRA_ARGS}
-  exit 1
+# Post-backup hook
+if [ -d "${HOOKS_DIR}" ]; then
+  run-parts -a "post-backup" --reverse --exit-on-error "${HOOKS_DIR}"
 fi
diff --git a/debian.Dockerfile b/debian.Dockerfile
index 1b275a3..547f44d 100644
--- a/debian.Dockerfile
+++ b/debian.Dockerfile
@@ -46,7 +46,7 @@ ENV POSTGRES_DB="**None**" \
     WEBHOOK_URL="**None**" \
     WEBHOOK_EXTRA_ARGS=""
 
-COPY backup.sh /backup.sh
+COPY backup.sh hooks /
 
 VOLUME /backups
 
diff --git a/hooks/00-webhook.sh b/hooks/00-webhook.sh
new file mode 100755
index 0000000..869adab
--- /dev/null
+++ b/hooks/00-webhook.sh
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+set -e
+
+# Possible actions: error, pre-backup, post-backup
+ACTION="${1}"
+
+if [ "${WEBHOOK_URL}" != "**None**" ]; then
+  case "${ACTION}" in
+    "error")
+      echo "Execute error webhook call to ${WEBHOOK_URL}"
+      curl --request POST \
+        --url "${WEBHOOK_URL}" \
+        --header 'Content-Type: application/json' \
+        --data '{"status": "error"}' \
+        --max-time 10 \
+        --retry 5 \
+        ${WEBHOOK_EXTRA_ARGS}
+      ;;
+#   "pre-backup")
+#     echo "Nothing to do"
+#     ;;
+    "post-backup")
+      echo "Execute post-backup webhook call to ${WEBHOOK_URL}"
+      curl --request POST \
+        --url "${WEBHOOK_URL}" \
+        --header 'Content-Type: application/json' \
+        --data '{"status": "post-backup"}' \
+        --max-time 10 \
+        --retry 5 \
+        ${WEBHOOK_EXTRA_ARGS}
+      ;;
+  esac
+fi