Ignite wrapper

[chanwit]

This PR introduce ignitew, a self-contained binary bundling ignite and CNI plugin binaries together.

ignitew can be used as a drop-in replacement of ignite OOTB without user manually installing CNI plugins.

It uses the excellent warp-packer https://github.com/dgiagio/warp to create the self contained binary. It uses no sandbox, so that the behaviour could be expected to be similar to the normal ignite.

Example:

$ sudo ls -al /opt/cni/bin/bridge
ls: cannot access '/opt/cni/bin/bridge': No such file or directory
$ sudo ls -al /opt/cni/bin/loopback
ls: cannot access '/opt/cni/bin/loopback': No such file or directory
$ ./ignitew version
Ignite version: version.Info{Major:"0", Minor:"6+", GitVersion:"v0.6.0-108+472f5f5d9ca49f", GitCommit:"472f5f5d9ca49f63d55bf2433d
e7eeafc946787b", GitTreeState:"clean", BuildDate:"2019-10-16T12:19:41Z", GoVersion:"go1.12.10", Compiler:"gc", Platform:"linux/am
d64"}
Firecracker version: v0.18.0
Runtime: containerd
$ sudo ./ignitew run weaveworks/ignite-ubuntu --ssh
INFO[0001] Created VM with ID "eee36d65bf8d132c" and name "little-forest" 
INFO[0001] Networking is handled by "cni"               
INFO[0001] Started Firecracker VM "eee36d65bf8d132c" in a container with ID "ignite-eee36d65bf8d132c" 
$ sudo ./ignitew exec little-forest -- uname -a
Linux localhost.localdomain 4.19.47 #1 SMP Tue Jul 16 18:57:23 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
$ sudo ./ignitew rm -f little-forest
INFO[0000] Removing the container with ID "ignite-eee36d65bf8d132c" from the "cni" network 
INFO[0000] Removed VM with name "little-forest" and ID "eee36d65bf8d132c" 

[stealthybox]

The Makefile needs to be updated to output ignitew to the proper bin/arch directories with a symlink.

We should make note whether this also supports ARM64 builds.

[stealthybox]

A build shows that the resulting binary size of ignitew:ignite is 51M vs. 35M.

This is likely just the size of the CNI binaries themselves. It's unfortunate because I believe every one of those is an independent Go binary :sweat_smile:

[fire-ant]

This is a pretty cool all-in-one solution, has it just dropped to the bottom of the backlog?