Feat: Implementing resizable/error exec stream

[yue9944882]

Kubelet is actually exposing a set of channels in the exec webconnection:

0. stdin
1. stdout
2. stderr
3. kubelet connection error
4. resizing

this pull adds access for the last two channel

/cc @brendandburns

[brendandburns]

What is the purpose of adding these interfaces? Why not just add the methods to ExecProcess?

[yue9944882]

What is the purpose of adding these interfaces?

the standard interface java.lang.Process only exposes access to three streams: stdin/stdout/stderr. while for a complete implementation of "web-terminal", we will have to leave the developers public access to another stream named "resize" which tells the kubernetes exec stream to probably adjust the terminals width&height..

Why not just add the methods to ExecProcess?

it is protected. otherwise how do you think about promote it to a public inner class?

[brendandburns]

I guess my feeling is you're going to have to cast it one way or the other:

Process p = Exec.exec(...);
ResizableExecStream res = (ResizableExecStream)p;
res.getResizeStream();
...

vs

ExecProcess p = (ExecProcess) Exec.exec(...);
p.getResizeStream();

I don't see the win from the interfaces, but I could be wrong.

[yue9944882]

i reverted the interfaces and made the class ExecProcess public w/ the new getters, wdyt?

[brendandburns]

/lgtm
/approve

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[myoss]

@yue9944882 hello, how to usage this ? resize web terminal

ExecProcess p = (ExecProcess) Exec.exec(...);
p.getResizeStream();