Test-infra: updateconfig: use a local clone to retrieve files, not the GitHub API

[stevekuznetsov]

In the updateconfig plugin, we need to fetch the content of files before we upload them to the cluster inside of ConfigMaps. To encapsulate this behavior, we have an interface:

https://github.com/kubernetes/test-infra/blob/f63737a069e07158d0d98d2d0399fe00d0df6a68/prow/plugins/updateconfig/updateconfig.go#L76-L79

The implementation of this interface used by the plugin, however, uses GitHub to fetch the file contents:

https://github.com/kubernetes/test-infra/blob/f63737a069e07158d0d98d2d0399fe00d0df6a68/prow/plugins/updateconfig/updateconfig.go#L81-L88

It is possible, however, to simply load the files from disk if the appropriate version of the repository is checked out, as is done in the config-bootstrapper:

https://github.com/kubernetes/test-infra/blob/f63737a069e07158d0d98d2d0399fe00d0df6a68/prow/cmd/config-bootstrapper/main.go#L141-L147

The current behavior of updateconfig is problematic as its token use scales linearly with the number of files changed that need to be uploaded. This allows for inadvertent DoS of the system by changing a large number of configuration files at once. The updateconfig plugin should be updated to clone the repository at the version that was pushed and use the local checkout to populate file contents.

/cc @cjwagner
/area prow/hook

[stevekuznetsov]

/good-first-issue

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[stevekuznetsov]

/help

[rajibmitra]

/assign rajibmitra

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[rajibmitra]

/assign rajibmitra

[rajibmitra]

@stevekuznetsov if I change the /updateconfig's gitHubFileGetter to osFileGetter , will it be able to
use the local checkout to populate file contents ?

[stevekuznetsov]

You'll need to call git.Clone() first to populate the filesystem, then use the osFileGetter@