Add ingress-nginx plugin

[alexkursell]

---

This PR add the kubectl plugin for https://github.com/kubernetes/ingress-nginx.

Checklist for plugin developers:

• Read the Plugin Naming Guide (for new plugins)
• Verify the installation from URL or a local archive works (kubectl krew install --manifest=[...] --archive=[...])

[ahmetb]

@alexkursell This is excellent and makes me super happy that Krew can host a first-party kubectl plugin from another Kubernetes sub-project.

Do you mind attending to the SIG CLI meeting and giving a short 5-10 min talk about your experience with Krew? Maybe I should ask for this after you release a few more versions and experience some friction along the way.

[ahmetb]

We recently added a homepage field, too.
Do you mind pointing it to the plugin documentation?

[alexkursell]

Once kubernetes/ingress-nginx#3982 is merged, I'll add a link to the docs.

[alexkursell]

fixed

[ahmetb]

I haven't tested this but it's a bit odd that the windows release is not distributed as .exe inside the tarball.

Krew will link it as .exe correctly, but I'm not sure if the symlink will work correctly because the target file isn't going to be named as .exe (see kubernetes-sigs/krew#131).

Basically, we don't know what happens on windows if we make a symlink to a source file named foo as bar.exe, and invoke bar.exe. Does foo actually get executed without needing an .exe extension?

[alexkursell]

I just booted into windows to try it, and it seems like it won't even download it properly:

 C:\Users\alex\.krew\bin\kubectl-krew.exe install --manifest ingress-nginx.yaml
Installing plugin: ingress-nginx
W0408 19:40:53.067709    4712 install.go:132] failed to install plugin "ingress-nginx": failed to dowload and move during installation: failed to move files: failed moving files: could not rename file from "C:\\Users\\alex\\AppData\\Local\\Temp\\krew-downloads\\ingress-nginx\\kubectl-ingress_nginx" to "C:\\Users\\alex\\AppData\\Local\\Temp\\krew-temp-move626560575\\kubectl-ingress_nginx": rename C:\Users\alex\AppData\Local\Temp\krew-downloads\ingress-nginx\kubectl-ingress_nginx C:\Users\alex\AppData\Local\Temp\krew-temp-move626560575\kubectl-ingress_nginx: The process cannot access the file because it is being used by another process.
F0408 19:40:53.067709    4712 root.go:52] failed to install some plugins: [ingress-nginx]

I installed sniff just fine, so I'm assuming it's the lack of a .exe extension. I might just leave Windows out at this point in time and fix this for the next release.

[ahmetb]

That sounds like a krew bug. We are usually careful around Windows file opening semantics, but looks like there's a problem.
Do you mind filing a bug to https://github.com/kubernetes-sigs/krew/issues/new with -v=10 flag? I wonder if other plugin installation are also failing.

[ahmetb]

Just saw the second part of your comment.
Can you try creating a .zip file with the windows binary (named *.exe) and run install again with --archive foo.zip? If this works, I'd be surprised, it doesn't explain the "file is used by another process" error.

[alexkursell]

I'll give this a try when I get home tonight. For now, I've just removed windows support entirely.

[ahmetb]

OK, let me know if you want me to go ahead and merge this.

[alexkursell]

Do you mind attending to the SIG CLI meeting and giving a short 5-10 min talk about your experience with Krew? Maybe I should ask for this after you release a few more versions and experience some friction along the way.

I'd love to! I do think it makes sense to wait a few releases though. My usage of krew up until this point has been pretty minimal so far.

[alexkursell]

@ahmetb I think this is good to merge unless you have any other concerns.

[ahmetb]

/lgtm
/approve

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