README
¶
fleet - a distributed init system
fleet ties together systemd and 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. The fleet and kubernetes comparison table has more information about the two systems.
Current status
fleet has seen production use for some time and is largely considered stable. However, there are known scalability limitations with its architecture. As such, it is not recommended to run fleet clusters larger than 100 nodes or with more than 1000 services. The fleet project is being maintained for bug fixes but the existing maintainers do not intend to add additional major features or significantly rework fleet to address these limitations.
If you are a developer and wish to help maintain fleet and improve its scalability, please email the maintainers.
Using fleet
Launching a unit with fleet is as simple as running fleetctl start:
$ 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:
$ 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:
$ 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.
Getting Started
Before you can deploy units, fleet must be deployed and configured 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.
Building
fleet must be built with Go 1.4+ 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 1.4+ 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 for more information.
Release Notes
See the releases tab for more information on each release.
Contributing
See CONTRIBUTING for details on submitting patches and contacting developers via IRC and mailing lists.
License
fleet is released under the Apache 2.0 license. See the 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.
Directories
¶
| Path | Synopsis |
|---|---|
|
Godeps
|
|
|
_workspace/src/github.com/coreos/etcd/client
Package client provides bindings for the etcd APIs.
|
Package client provides bindings for the etcd APIs. |
|
_workspace/src/github.com/coreos/go-systemd/activation
Package activation implements primitives for systemd socket activation.
|
Package activation implements primitives for systemd socket activation. |
|
_workspace/src/github.com/coreos/go-systemd/dbus
Integration with the systemd D-Bus API.
|
Integration with the systemd D-Bus API. |
|
_workspace/src/github.com/godbus/dbus
Package dbus implements bindings to the D-Bus message bus system.
|
Package dbus implements bindings to the D-Bus message bus system. |
|
_workspace/src/github.com/godbus/dbus/introspect
Package introspect provides some utilities for dealing with the DBus introspection format.
|
Package introspect provides some utilities for dealing with the DBus introspection format. |
|
_workspace/src/github.com/godbus/dbus/prop
Package prop provides the Properties struct which can be used to implement org.freedesktop.DBus.Properties.
|
Package prop provides the Properties struct which can be used to implement org.freedesktop.DBus.Properties. |
|
_workspace/src/github.com/pborman/uuid
The uuid package generates and inspects UUIDs.
|
The uuid package generates and inspects UUIDs. |
|
_workspace/src/github.com/vishvananda/netlink
Package netlink provides a simple library for netlink.
|
Package netlink provides a simple library for netlink. |
|
_workspace/src/github.com/vishvananda/netlink/nl
Package nl has low level primitives for making Netlink calls.
|
Package nl has low level primitives for making Netlink calls. |
|
_workspace/src/golang.org/x/crypto/curve25519
Package curve25519 provides an implementation of scalar multiplication on the elliptic curve known as curve25519.
|
Package curve25519 provides an implementation of scalar multiplication on the elliptic curve known as curve25519. |
|
_workspace/src/golang.org/x/crypto/ssh
Package ssh implements an SSH client and server.
|
Package ssh implements an SSH client and server. |
|
_workspace/src/golang.org/x/crypto/ssh/agent
Package agent implements the ssh-agent protocol, and provides both a client and a server.
|
Package agent implements the ssh-agent protocol, and provides both a client and a server. |
|
_workspace/src/golang.org/x/crypto/ssh/terminal
Package terminal provides support functions for dealing with terminals, as commonly found on UNIX systems.
|
Package terminal provides support functions for dealing with terminals, as commonly found on UNIX systems. |
|
_workspace/src/golang.org/x/net/context
Package context defines the Context type, which carries deadlines, cancelation signals, and other request-scoped values across API boundaries and between processes.
|
Package context defines the Context type, which carries deadlines, cancelation signals, and other request-scoped values across API boundaries and between processes. |
|
_workspace/src/google.golang.org/api/googleapi
Package googleapi contains the common code shared by all Google API libraries.
|
Package googleapi contains the common code shared by all Google API libraries. |
|
_workspace/src/google.golang.org/api/googleapi/internal/uritemplates
Package uritemplates is a level 4 implementation of RFC 6570 (URI Template, http://tools.ietf.org/html/rfc6570).
|
Package uritemplates is a level 4 implementation of RFC 6570 (URI Template, http://tools.ietf.org/html/rfc6570). |
|
_workspace/src/google.golang.org/api/googleapi/transport
Package transport contains HTTP transports used to make authenticated API requests.
|
Package transport contains HTTP transports used to make authenticated API requests. |
|
Fleet functional test suite These test files must be executed as described in README.md, they are not plain old Go unit tests.
|
Fleet functional test suite These test files must be executed as described in README.md, they are not plain old Go unit tests. |
|
Package schema provides access to the fleet API.
|
Package schema provides access to the fleet API. |