Scheduled Tasks With Google App Engine & Python
·2 mins
We’ll create a simple Hello World application that sends an e-mail every 5 minutes to reassure you that the Internet is still out there and still cares.
First, download and install the Google App Engine SDK.
For example:
```bash
wget http://googleappengine.googlecode.com/files/google_appengine_1.3.4.zip
unzip google_appengine_1.3.4.zip
Create a directory for your application:
```bash
mkdir helloworld
Create an app.yaml file to describe your application:
```yaml
application: helloworld
version: 1
runtime: python
api_version: 1handlers:
- url: /helloworld
script: helloworld.py
login: admin
Create a cron.yaml file to run your scheduled task:
```yaml
cron:
- description: hello... is it me you're looking for?
url: /helloworld
schedule: every 5 minutes
Create your script (changing the e-mail addresses, of course):
```python
#!/usr/bin/env python
#
# Hello World via e-mail
from google.appengine.api import mail
mail.send_mail(
sender="Your Email Address <you@example.com>",
to="Your Email Address <you@example.com >",
subject="Hello world",
body="Hello world"
)
Use appcfg.py inside the unzipped SDK to upload your application:
```bash
google_appengine/appcfg.py update helloworld
Enter your username and password when prompted. The output should look something like this:
```text
Application: helloworld; version: 1.
Server: appengine.google.com.
Scanning files on local disk.
Initiating update.
Cloning 2 application files.
Uploading 1 files and blobs.
Uploaded 1 files and blobs
Deploying new version.
Checking if new version is ready to serve.
Will check again in 1 seconds.
Checking if new version is ready to serve.
Will check again in 2 seconds.
Checking if new version is ready to serve.
Closing update: new version is ready to start serving.
Uploading cron entries.
Simple as that. Enjoy.