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This takes some of the machinery from CNI and from the rkt networking code, and turns it into a library that can be linked into go apps. Included is an example command-line application that uses the library, called `cnitool`. Other headline changes: * Plugin exec'ing is factored out The motivation here is to factor out the protocol for invoking plugins. To that end, a generalisation of the code from api.go and pkg/plugin/ipam.go goes into pkg/invoke/exec.go. * Move argument-handling and conf-loading into public API The fact that the arguments get turned into an environment for the plugin is incidental to the API; so, provide a way of supplying them as a struct or saying "just use the same arguments as I got" (the latter is for IPAM plugins).
cni - the Container Network Interface
What is CNI?
CNI, the Container Network Interface, is a proposed standard for configuring network interfaces for Linux application containers. The standard consists of a simple specification for how executable plugins can be used to configure network namespaces; this repository also contains a go library implementing that specification.
The specification itself is contained in SPEC.md
Why develop CNI?
Application containers on Linux are a rapidly evolving area, and within this space networking is a particularly unsolved problem, as it is highly environment-specific. We believe that every container runtime will seek to solve the same problem of making the network layer pluggable. In order to avoid duplication, we think it is prudent to define a common interface between the network plugins and container execution. Hence we are proposing this specification, along with an initial set of plugins that can be used by different container runtime systems.
How do I use CNI?
Requirements
CNI requires Go 1.4+ to build.
Included Plugins
This repository includes a number of common plugins that can be found in plugins/ directory. Please see Documentation/ folder 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.
Start out by creating a netconf file to describe a network:
$ mkdir -p /etc/cni/net.d
$ cat >/etc/cni/net.d/10-mynet.conf <<EOF
{
"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
The directory /etc/cni/net.d is the default location in which the scripts will look for net configurations.
Next, build the plugins:
$ ./build
Finally, execute a command (ifconfig in this example) in a private network namespace that has joined mynet network:
$ 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 instructions in the previous section to define a netconf and build the plugins.
Next, docker-run.sh script wraps docker run command to execute the plugins prior to entering the container:
$ CNI_PATH=`pwd`/bin
$ cd scripts
$ sudo CNI_PATH=$CNI_PATH ./docker-run.sh --rm busybox:latest /sbin/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)