F5 BIG-IP webhook

This is an integration between Scalr and the F5 BIG-IP load balancer. This webhook can be used to automatically register and deregister Scalr instances from F5 load balancing pools.

Setup instructions

The instructions below are written for RHEL 7 / Centos 7. Adapt as necessary for other distributions.

Webhook handler setup

Install the required packages:

yum install epel-release
yum install git gcc python python-devel python-pip uwsgi uwsgi-plugin-python

Retrieve the webhook code:

mkdir -p /opt/f5-bigip-webhook
cd /opt/f5-bigip-webhook
git clone https://github.com/scalr-integrations/f5-bigip-webhook.git .

Install the Python dependencies

pip install -r requirements.txt

Configure uwsgi to serve the webhook

cp uwsgi.ini /etc/uwsgi.d/f5-bigip-webhook.ini
chown uwsgi:uwsgi /etc/uwsgi.d/f5-bigip-webhook.ini
systemctl enable uwsgi

Uwsgi will bind to 0.0.0.0 and serve the webhook on port 5010 by default. Edit the ini file to change this behaviour.

Scalr webhook setup

Log into Scalr at the scope you want to use this webhook in, and click on Webhooks in the main menu. In the Endpoints section, create a new endpoint with URL: http://<server-ip>:5010/bigip/

Note down the signing key that Scalr generated, we will need it later.

In the Webhooks section, create a new Webhook with the following settings:

Name: BIG-IP integration
Endpoints: the endpoint you just created
Events: HostUp, BeforeHostTerminate, HostDown
Farms: All farms
Timeout: 10 sec
Max. delivery attempts: 3

and click on the save icon to save the webhook.

Webhook configuration

Edit /etc/uwsgi.d/f5-bigip-webhook.ini and fill in the configuration variables.

Then restart uwsgi to reload the configuration:

systemctl restart uwsgi

Testing and troubleshooting

The uwsgi logs are appended to /var/log/messages.

To check that the web server is serving our webhook, run the following command on the webhook server:

curl -XPOST http://localhost:5010/bigip/

You should get a 403 error, because our request was not signed. If that is not the case, check for errors in the uwsgi logs.

Next you should configure a Farm Role to be registered in a load balancing pool. Go into a Farm Role's configuration, and click on Global Variables. Create a new global variable named BIGIP_CONFIG. Click on the lock button to prevent it from being changed at a lower scope. The value should contain the following settings, in this order, separated by commas:

pool name: the name of the load balancing pool
instance port: The port that the traffic should be forwarded to on the instances
virtual server name: the name of the virtual server
virtual server address: The address the virtual server should listen on
virtual server port: The port the virtual server should listen on
upstream ip: OPTIONAL, one of: public, private, auto. The IP to register in the load balancing pool. auto default to the public IP, but fallbacks to the private IP if the server has no public IP. The default is auto.
partition: OPTIONAL, defaults to Common.
load balancing method: OPTIONAL, defaults to least-connections-member.

Example values:

my_app_pool,8000,my_app_virtual_server,10.0.0.10,80
test_pool, 8443, test_virtual_server, 10.0.0.11, 8000, auto, PartitionName, round-robin

When the first instance is started, the webhook will create the virtual server and the pool in the BIG-IP system. The virtual server is working in TCP mode. As additional instances come up or go down, they will be added to or removed from the pool. If no servers are left in the pool, the virtual server and the pool will be deleted.