MySQL version of trigger, setup instructions in README

README.md

@@ -1,13 +1,53 @@
 # healthchecks
 
-healthchecks is a watchdog for your cron jobs. It's a web server that listens for pings from your cron jobs, plus a web interface. 
+healthchecks is a watchdog for your cron jobs. It's a web server that listens for pings from your cron jobs, plus a web interface.
 
 It is live here: [http://healthchecks.io/](http://healthchecks.io/)
 
 The building blocks are:
 
-* Python 3
-* virtualenv
+* Python 2 or Python 3
 * Django 1.8
-* PostgreSQL
+* PostgreSQL or MySQL
+
+## Setting Up for Development
+
+These are instructions for setting up HealthChecks Django app
+in development environment.
+
+* prepare directory for project code and virtualenv:
+
+        $ mkdir -p ~/webapps
+        $ cd ~/webapps
+
+* prepare virtual environment
+  (with virtualenv you get pip, we'll use it soon to install requirements):
+
+        $ virtualenv --python=python3 hc-venv
+        $ source hc-venv/bin/activate
+
+* check out project code:
+
+        $ git clone git@github.com:healthchecks/healthchecks.git
+
+* install requirements (Django, ...) into virtualenv:
+
+        $ pip install -r healthchecks/requirements.txt
+
+* make sure PostgreSQL server is installed and running, create
+  database "hc":
+
+        $ psql --user postgres
+        postgres=# create database hc;
+
+* create database tables, triggers, superuser:
+
+        $ cd ~/webapps/healthchecks
+        $ ./manage.py migrate
+        $ ./manage.py ensuretriggers
+        $ ./manage.py createsuperuser
+
+* run development server:
+
+        $ ./manage.py runserver
 

hc/api/management/commands/ensuretriggers.py

@@ -2,26 +2,45 @@ from django.core.management.base import BaseCommand
 from django.db import connection
 
 
+def _pg(cursor):
+    cursor.execute("""
+    CREATE OR REPLACE FUNCTION update_alert_after()
+    RETURNS trigger AS $update_alert_after$
+        BEGIN
+            IF NEW.last_ping IS NOT NULL THEN
+                NEW.alert_after := NEW.last_ping + NEW.timeout + NEW.grace;
+            END IF;
+            RETURN NEW;
+        END;
+    $update_alert_after$ LANGUAGE plpgsql;
+
+    DROP TRIGGER IF EXISTS update_alert_after ON api_check;
+
+    CREATE TRIGGER update_alert_after
+    BEFORE INSERT OR UPDATE OF last_ping, timeout, grace  ON api_check
+    FOR EACH ROW EXECUTE PROCEDURE update_alert_after();
+    """)
+
+
+def _mysql(cursor):
+    cursor.execute("""
+    DROP TRIGGER IF EXISTS update_alert_after;
+
+    CREATE TRIGGER update_alert_after
+    BEFORE UPDATE ON api_check
+    FOR EACH ROW SET NEW.alert_after = NEW.last_ping + INTERVAL (NEW.timeout + NEW.grace) MICROSECOND;
+    """)
+
+
 class Command(BaseCommand):
     help = 'Ensures triggers exist in database'
 
     def handle(self, *args, **options):
         cursor = connection.cursor()
 
-        cursor.execute("""
-CREATE OR REPLACE FUNCTION update_alert_after()
-RETURNS trigger AS $update_alert_after$
-    BEGIN
-        IF NEW.last_ping IS NOT NULL THEN
-            NEW.alert_after := NEW.last_ping + NEW.timeout + NEW.grace;
-        END IF;
-        RETURN NEW;
-    END;
-$update_alert_after$ LANGUAGE plpgsql;
-
-DROP TRIGGER IF EXISTS update_alert_after ON api_check;
-
-CREATE TRIGGER update_alert_after
-BEFORE INSERT OR UPDATE OF last_ping, timeout, grace  ON api_check
-FOR EACH ROW EXECUTE PROCEDURE update_alert_after();
-        """)
+        if connection.vendor == "postgresql":
+            _pg(cursor)
+            print("Created PostgreSQL trigger")
+        if connection.vendor == "mysql":
+            _mysql(cursor)
+            print("Created MySQL trigger")