goat-eni

Goat for ENI

Behavior

goat eni should behave correctly with no parameters. It is configured entirely with tags (explained below). It logs to stderr by default.

It takes some options:

• --dry - dry run, don't execute any commands
• --log-level=<level> - logrus log levels (i.e. debug, info, warn, error, fatal, panic)
• --debug - an interactive debug mode which prompts to continue after every phase so you can explore the state between phases

Fresh run

The event flow is roughly the following:

• Get EC2 metadata on the running instance
• Use metadata to establish an EC2 client and scan ENIs
• Attach the ENIs it needs based on their tags

Setting up the ENI - ec2-net-utils

There's a project to port ec2-net-utils, a tool available on Amazon Linux AMIs, to CentOS/systemd, here.

I forked it and created a release. This tool is highly recommended to perform the actual setup of your ENI:

sudo yum install -y https://github.com/sevagh/ec2-utils/releases/download/v0.5.3/ec2-net-utils-0.5-2.fc25.noarch.rpm
sudo systemctl enable elastic-network-interfaces

DeviceIndex

ENI attachments take a parameter called DeviceIndex. Goat isn't smart, and always starts from DeviceIndex 1.

This means that your EC2 instance should have no attached ENIs.

If it does, they should be the ones that goat was going to attach anyway, not external ENIs that have no goat tags.

Tags

These are the tags you need: