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[](https://travis-ci.org/containernetworking/cni)
[](https://coveralls.io/github/containernetworking/cni?branch=master)
[](https://cryptic-tundra-43194.herokuapp.com/)
# CNI - the Container Network Interface
## What is CNI?
The CNI (_Container Network Interface_) project consists of a specification and libraries for writing plugins to configure network interfaces in Linux containers, along with a number of supported plugins.
CNI concerns itself only with network connectivity of containers and removing allocated resources when the container is deleted.
Because of this focus, CNI has a wide range of support and the specification is simple to implement.
As well as the [specification](SPEC.md), this repository contains the Go source code of a library for integrating CNI into applications, an example command-line tool, a template for making new plugins, and the supported plugins.
The template code makes it straight-forward to create a CNI plugin for an existing container networking project.
CNI also makes a good framework for creating a new container networking project from scratch.
## Why develop CNI?
Application containers on Linux are a rapidly evolving area, and within this area networking is not well addressed as it is highly environment-specific.
We believe that many container runtimes and orchestrators will seek to solve the same problem of making the network layer pluggable.
To avoid duplication, we think it is prudent to define a common interface between the network plugins and container execution: hence we put forward this specification, along with libraries for Go and a set of plugins.
## Who is using CNI?
### Container runtimes
- [rkt - container engine](https://coreos.com/blog/rkt-cni-networking.html)
- [Kurma - container runtime](http://kurma.io/)
- [Kubernetes - a system to simplify container operations](http://kubernetes.io/docs/admin/network-plugins/)
- [Cloud Foundry - a platform for cloud applications](https://github.com/cloudfoundry-incubator/netman-release)
- [Mesos - a distributed systems kernel](https://github.com/apache/mesos/blob/master/docs/cni.md)
### 3rd party plugins
- [Project Calico - a layer 3 virtual network](https://github.com/projectcalico/calico-cni)
- [Weave - a multi-host Docker network](https://github.com/weaveworks/weave)
- [Contiv Networking - policy networking for various use cases](https://github.com/contiv/netplugin)
- [SR-IOV](https://github.com/hustcat/sriov-cni)
- [Cilium - BPF & XDP for containers](https://github.com/cilium/cilium)
- [Infoblox - enterprise IP address management for containers](https://github.com/infobloxopen/cni-infoblox)
The CNI team also maintains some [core plugins](plugins).
## Contributing to CNI
We welcome contributions, including [bug reports](https://github.com/containernetworking/cni/issues), and code and documentation improvements.
If you intend to contribute to code or documentation, please read [CONTRIBUTING.md](CONTRIBUTING.md). Also see the [contact section](#contact) in this README.
## How do I use CNI?
### Requirements
CNI requires Go 1.5+ to build.
Go 1.5 users will need to set GO15VENDOREXPERIMENT=1 to get vendored
dependencies. This flag is set by default in 1.6.
### Included Plugins
This repository includes a number of common plugins in the `plugins/` directory.
Please see the [Documentation/](Documentation/) directory for documentation about particular plugins.
### Running the plugins
The scripts/ directory contains two scripts, `priv-net-run.sh` and `docker-run.sh`, that can be used to exercise the plugins.
**note - priv-net-run.sh depends on `jq`**
Start out by creating a netconf file to describe a network:
```bash
$ mkdir -p /etc/cni/net.d
$ cat >/etc/cni/net.d/10-mynet.conf <<EOF
{
"cniVersion": "0.2.0",
"name": "mynet",
"type": "bridge",
"bridge": "cni0",
"isGateway": true,
"ipMasq": true,
"ipam": {
"type": "host-local",
"subnet": "10.22.0.0/16",
"routes": [
{ "dst": "0.0.0.0/0" }
]
}
}
EOF
$ cat >/etc/cni/net.d/99-loopback.conf <<EOF
{
"cniVersion": "0.2.0",
"type": "loopback"
}
EOF
```
The directory `/etc/cni/net.d` is the default location in which the scripts will look for net configurations.
Next, build the plugins:
```bash
$ ./build
```
Finally, execute a command (`ifconfig` in this example) in a private network namespace that has joined the `mynet` network:
```bash
$ CNI_PATH=`pwd`/bin
$ cd scripts
$ sudo CNI_PATH=$CNI_PATH ./priv-net-run.sh ifconfig
eth0 Link encap:Ethernet HWaddr f2:c2:6f:54:b8:2b
inet addr:10.22.0.2 Bcast:0.0.0.0 Mask:255.255.0.0
inet6 addr: fe80::f0c2:6fff:fe54:b82b/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:1 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:90 (90.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
```
The environment variable `CNI_PATH` tells the scripts and library where to look for plugin executables.
## Running a Docker container with network namespace set up by CNI plugins
Use the instructions in the previous section to define a netconf and build the plugins.
Next, docker-run.sh script wraps `docker run`, to execute the plugins prior to entering the container:
```bash
$ CNI_PATH=`pwd`/bin
$ cd scripts
$ sudo CNI_PATH=$CNI_PATH ./docker-run.sh --rm busybox:latest ifconfig
eth0 Link encap:Ethernet HWaddr fa:60:70:aa:07:d1
inet addr:10.22.0.2 Bcast:0.0.0.0 Mask:255.255.0.0
inet6 addr: fe80::f860:70ff:feaa:7d1/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:1 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:90 (90.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
```
## What might CNI do in the future?
CNI currently covers a wide range of needs for network configuration due to it simple model and API.
However, in the future CNI might want to branch out into other directions:
- Dynamic updates to existing network configuration
- Dynamic policies for network bandwidth and firewall rules
If these topics of are interest, please contact the team via the mailing list or IRC and find some like-minded people in the community to put a proposal together.
## Contact
For any questions about CNI, please reach out on the mailing list:
- Email: [cni-dev](https://groups.google.com/forum/#!forum/cni-dev)
- IRC: #[containernetworking](irc://irc.freenode.org:6667/#containernetworking) channel on freenode.org
- Slack: [containernetworking.slack.com](https://cryptic-tundra-43194.herokuapp.com)
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