From 620e910477b122d89a146ae79b877e2fc0c8859b Mon Sep 17 00:00:00 2001
From: Graham Dumpleton <Graham.Dumpleton@gmail.com>
Date: Thu, 16 Mar 2017 17:12:13 +1100
Subject: [PATCH] Add readiness and liveness probe scripts.

---
 .s2i/environment          |  1 +
 requirements.txt          |  1 +
 scripts/alive             | 30 ++++++++++++++++++++++++++++++
 scripts/check-database.py | 37 +++++++++++++++++++++++++++++++++++++
 scripts/check-server.py   |  7 +++++++
 scripts/ready             | 30 ++++++++++++++++++++++++++++++
 6 files changed, 106 insertions(+)
 create mode 100755 scripts/alive
 create mode 100644 scripts/check-database.py
 create mode 100644 scripts/check-server.py
 create mode 100755 scripts/ready

diff --git a/.s2i/environment b/.s2i/environment
index 76be426..125c848 100644
--- a/.s2i/environment
+++ b/.s2i/environment
@@ -2,3 +2,4 @@ S2I_SCRIPTS_PATH=/usr/libexec/s2i
 S2I_BASH_ENV=/opt/app-root/etc/scl_enable
 DISABLE_COLLECTSTATIC=1
 DISABLE_MIGRATE=1
+PYTHONUNBUFFERED=1
diff --git a/requirements.txt b/requirements.txt
index f836030..8c13019 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,3 +3,4 @@ dj_database_url
 mod_wsgi
 Pillow
 psycopg2
+requests
diff --git a/scripts/alive b/scripts/alive
new file mode 100755
index 0000000..bdb0400
--- /dev/null
+++ b/scripts/alive
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -eo pipefail
+
+HERE=`dirname $0`
+
+ready() {
+    echo " -----> Starting liveness script."
+
+    # Check web server.
+
+    echo " -----> Checking server is working."
+
+    python $HERE/check-server.py
+
+    # Check database.
+
+    echo " -----> Checking database is working."
+
+    if [ x"$DATABASE_URL" != x"" ]; then
+        (cat - | python manage.py shell --plain) << !
+import runpy
+_ = runpy.run_path('$HERE/check-database.py')
+!
+    fi
+
+    echo " -----> Stopping liveness script."
+}
+
+ready 2>&1 | tee -a /proc/1/fd/1
diff --git a/scripts/check-database.py b/scripts/check-database.py
new file mode 100644
index 0000000..9424c48
--- /dev/null
+++ b/scripts/check-database.py
@@ -0,0 +1,37 @@
+from __future__ import print_function
+
+import sys
+import time
+
+import django
+
+django.setup()
+
+from django.db import connection
+
+remaining = 600.0
+delay = 2.0
+
+success = False
+
+while remaining > 0.0:
+    try:
+        print('Check whether database is ready...')
+        cursor = connection.cursor()
+        with cursor:
+            cursor.execute('SELECT 1')
+            cursor.fetchall()
+
+        success = True
+
+        break
+
+    except Exception:
+        pass
+
+    time.sleep(delay)
+
+if not success:
+    print('Failed to connect to database')
+
+    sys.exit(1)
diff --git a/scripts/check-server.py b/scripts/check-server.py
new file mode 100644
index 0000000..471c085
--- /dev/null
+++ b/scripts/check-server.py
@@ -0,0 +1,7 @@
+import os
+import requests
+
+hostname = os.environ['HOSTNAME']
+
+response = requests.get('http://%s:8080/' % hostname)
+response.raise_for_status()
diff --git a/scripts/ready b/scripts/ready
new file mode 100755
index 0000000..ffe9efa
--- /dev/null
+++ b/scripts/ready
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+set -eo pipefail
+
+HERE=`dirname $0`
+
+ready() {
+    echo " -----> Starting readiness script."
+
+    # Check web server.
+
+    echo " -----> Checking server is working."
+
+    python $HERE/check-server.py
+
+    # Check database.
+
+    echo " -----> Checking database is working."
+
+    if [ x"$DATABASE_URL" != x"" ]; then
+        (cat - | python manage.py shell --plain) << !
+import runpy
+_ = runpy.run_path('$HERE/check-database.py')
+!
+    fi
+
+    echo " -----> Stopping readiness script."
+}
+
+ready 2>&1 | tee -a /proc/1/fd/1