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https://github.com/coreos/fleet

fleet ties together systemd and etcd into a distributed init system
https://github.com/coreos/fleet

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fleet ties together systemd and etcd into a distributed init system

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## WARNINGWARNINGWARNING Deprecation warning WARNINGWARNINGWARNING

fleet is no longer developed or maintained by CoreOS. After February 1, 2018, a fleet container image will continue to be available from the CoreOS Quay registry, but will not be shipped as part of Container Linux. CoreOS instead [recommends Kubernetes for all clustering needs](https://coreos.com/blog/migrating-from-fleet-to-kubernetes.html).



The project exists here for historical reference. If you are interested in the future of the project and taking over stewardship, please contact [email protected]



# fleet - a distributed init system



[![Build Status](https://travis-ci.org/coreos/fleet.png?branch=master)](https://travis-ci.org/coreos/fleet)

[![Build Status](https://semaphoreci.com/api/v1/coreos/fleet/branches/master/badge.svg)](https://semaphoreci.com/coreos/fleet)



fleet ties together [systemd][coreos-systemd] and [etcd][etcd] into a simple distributed init system. Think of it as an extension of systemd that operates at the cluster level instead of the machine level.



**This project is quite low-level, and is designed as a foundation for higher order orchestration.** fleet is a cluster-wide elaboration on systemd units, and is not a container manager or orchestration system. fleet supports basic scheduling of systemd units across nodes in a cluster. Those looking for more complex scheduling requirements or a first-class container orchestration system should check out [Kubernetes][kubernetes]. The [fleet and kubernetes comparison table][fleet-vs-k8s] has more information about the two systems.



## Current status



The fleet project is [no longer maintained](#deprecation-warning).



As of v1.0.0, fleet has seen production use for some time and is largely considered stable.

However, there are [various known and unresolved issues](https://github.com/coreos/fleet/issues), including [scalability limitations][fleet-scaling] with its architecture.

As such, it is not recommended to run fleet clusters larger than 100 nodes or with more than 1000 services.



## Using fleet



Launching a unit with fleet is as simple as running `fleetctl start`:



```sh

$ fleetctl start examples/hello.service

Unit hello.service launched on 113f16a7.../172.17.8.103

```



The `fleetctl start` command waits for the unit to get scheduled and actually start somewhere in the cluster.

`fleetctl list-unit-files` tells you the desired state of your units and where they are currently scheduled:



```sh

$ fleetctl list-unit-files

UNIT            HASH     DSTATE    STATE     TMACHINE

hello.service   e55c0ae  launched  launched  113f16a7.../172.17.8.103

```



`fleetctl list-units` exposes the systemd state for each unit in your fleet cluster:



```sh

$ fleetctl list-units

UNIT            MACHINE                    ACTIVE   SUB

hello.service   113f16a7.../172.17.8.103   active   running

```



## Supported Deployment Patterns



fleet is not intended to be an all-purpose orchestration system, and as such supports only a few simple deployment patterns:



* Deploy a single unit anywhere on the cluster

* Deploy a unit globally everywhere in the cluster

* Automatic rescheduling of units on machine failure

* Ensure that units are deployed together on the same machine

* Forbid specific units from colocation on the same machine (anti-affinity)

* Deploy units to machines only with specific metadata



These patterns are all defined using [custom systemd unit options][unit-files].



## Getting Started



Before you can deploy units, fleet must be [deployed and configured][deploy-and-configure] on each host in your cluster. (If you are running CoreOS, fleet is already installed.)



After you have machines configured (check `fleetctl list-machines`), get to work with the [client][using-the-client.md].



### Building



fleet must be built with Go 1.5+ on a Linux machine. Simply run `./build` and then copy the binaries out of `bin/` directory onto each of your machines. The tests can similarly be run by simply invoking `./test`.



If you're on a machine without Go 1.5+ but you have Docker installed, run `./build-docker` to compile the binaries instead.



## Project Details



### API



The fleet API uses JSON over HTTP to manage units in a fleet cluster.

See the [API documentation][api-doc] for more information.



### Release Notes



See the [releases tab][releases] for more information on each release.



### License



fleet is released under the Apache 2.0 license. See the [LICENSE][license] file for details.



Specific components of fleet use code derivative from software distributed under other licenses; in those cases the appropriate licenses are stipulated alongside the code.



[api-doc]: Documentation/api-v1.md

[contributing]: CONTRIBUTING.md

[coreos-systemd]: https://github.com/coreos/docs/blob/master/os/getting-started-with-systemd.md

[deploy-and-configure]: Documentation/deployment-and-configuration.md

[etcd]: https://github.com/coreos/etcd

[fleet-scaling]: Documentation/fleet-scaling.md

[fleet-vs-k8s]: Documentation/fleet-k8s-compared.md

[kubernetes]: http://kubernetes.io

[license]: LICENSE

[maintainers]: MAINTAINERS

[releases]: https://github.com/coreos/fleet/releases

[unit-files]: Documentation/unit-files-and-scheduling.md#fleet-specific-options

[using-the-client.md]: Documentation/using-the-client.md