apheleia

apheleia is a reconfiguration utility for nerve similar to Yelp's nerve-tools configure_nerve, but with its data based in zookeeper and not on disk. The zookeeper data can be updated from YAML configuration files via the apheleia CLI tool. This is to reduce the unneeded complexity introduced by having to keep local files of the configuration around on every machine. Since zookeeper already contains critical data in most mesos deployments, there is little reason to not use it as storage for service declarations as well.

Justification

Yelp's nerve-tools configure_nerve works well for exposing Marathon services, but breaks down when you want to expose mesos tasks in a more generalized manner. Apheleia will be able to select tasks to expose from the mesos slave API via simple regex filters, rather than having to look explicitly for marathon services. This means that your service discovery mechanism is not so closely tied to the mesos framework that you choose, though it will require slightly more configuration on a per-service basis.

Usage

apheleia [options] command [commandArgs...]

Commands

The following commands are available to the apheleia CLI.

Command	Description	Arguments
configureNerve	Generates a nerve configuration file and restarts nerve (if the configuration changed)	None
updateZk	Updates zookeeper with the given YAML files describing services	list of yml service description files

Flags

The following flags may be used to configure apheleia.

Flag	Example	Description
-zk hosts	-zk localhost:2181,otherHost:2181	comma separated list of zookeeper hosts and ports
-zkPath path	-zkPath /apheleia	zookeeper path of the apheleia node
-slave slaveURL	-slave http://localhost:5051	base URL of the mesos slave API with which to communicate
-nerveCfg nerveCfgFile	-nergeCfg /opt/smartstack/nerve/nerve.conf	nerve configuration file to manage

Environment Variables

The following environment variables may be used to configure apheleia

Variable	Description
APHELEIA_NERVE_RESTART_CMD	bash command used to restart nerve after a configuration update

Examples

Configure nerve (systemd)

The following example configures nerve running under systemd for an environment where zookeeper and the mesos slave api are running locally on standard ports

#!/usr/bin/env bash

export APHELEIA_NERVE_RESTART_CMD="systemctl restart nerve"
apheleia \
	-zk localhost:2181 \
	-zkPath /apheleia \
	-slave http://localhost:5051 \
	-nerveCfg /opt/smartstack/nerve/nerve.conf \
	configureNerve

Update zookeeper data from dir of yaml files

The following example updates zookeeper data for apheleia from yaml service definition files in the ./services directory

Like the previous example, it assumes an environment where zookeeper is running locally on the standard port.

#!/usr/bin/env bash

service_dir=services
service_files=$(find "$service_dir" -type f -name '*.yml')

apheleia \
	-zk localhost:2181 \
	-zkPath /apheleia \
	updateZk $service_files

License

Licensed under GPLv3. See LICENSE file.