rwillard / sidekick

Python-based etcd presence announcer

sidekick

If you're running services on CoreOS or using etcd as a way to keep track of different services that are running across your cluster, sidekick is a flexible presence service that was built for you.

Dependencies

Some system dependencies that are expected to run sidekick:

• Python >= 3.4.3
• etcd >= 2.0

Python dependencies can be installed by running the following:

pip install -r requirements.txt

Usage

sidekick is intended to be used as a Docker container, linked to the host's networking stack and Docker daemon.

Linking the host's networking stack allows sidekick to easily check the health of the service without any networking complexities. Linking to the host's Docker daemon allows us to easily check for a service's publicly binded ports and announce those to etcd.

Enough talk! Let's go through an example. Let's start up a simple NGINX service:

docker run -d --name nginx -p 80 -p 443 nginx:1.9

Notice that we don't have to explicitly say the local host port for NGINX. We'll let Docker figure out an open port and simply announce that port after inspection. Now we can run our sidekick:

python sidekick.py --name nginx --ip localhost

If you're running on OSX and using boot2docker, you'll need to add --check-ip $(boot2docker ip) to the list of arguments since sidekick expects the service to be accessible locally.

sidekick Command Line Arguments

sidekick is very flexible and takes a number of command line arguments to fit customized deployment onto clusters.

Mandatory Arguments

Argument	Description
--name	Name of the Docker container to inspect.
--ip	The IP to use in the URI for the presence announcement.

Optional Arguments

Argument	Description
--check-ip	IP used to check a service's health. By default, services are expected to run locally. Default: 0.0.0.0
--docker	Docker server URI. Default: unix:///var/run/docker.sock
--domain	The domain/service name for this service. Default: example.com
--etcd-host	ETCD cluster peer host. Default: localhost
--etcd-port	ETCD cluster peer port. Default: 4001
--prefix	The etcd folder in which to announce running services. Default: /services
--timeout	The number of seconds to wait until the next health check. Default: 10
--ttl	ETCD ttl in seconds for the service announcement. Default: 60