More flexibility in configuration of client proxy(#1446)

[denchenko]

• ProxyURL client option
• Posibility to use credentials from proxy string

fixes #1446

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[denchenko]

I signed it. чт, 17 авг. 2017, 4:55 PM googlebot <notifications@github.com>:

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[googlebot]

CLAs look good, thanks!

[denchenko]

Fixed tests and added case for using custom proxy.

[menghanl]

Thanks for the contribution and sorry for the late reply.

One issue with your proposed fix is that, the new dial option WithProxyURL is too specific for this problem. And it would be better if we can get a more general solution.

A proxy dialer actually consists of three parts:

• mapper from the target address to the proxy server address (for example, get proxy env variable)
• dialer
• handshaker

Currently, we have these three components, but they are not explicitly called out and not exported.

The proposal we make here is to make the mapper and handshaker public, so users can compose their custom proxy dialer as they want, using these components.

This includes:

• Add a new proxy package
• Move code in proxy.go to the new proxy package
• Export ProxyFromEnv and HTTPConnectHandshake
  • ProxyFromEnv would return one more http.Header value for credentials
  • HTTPConnectHandshake would take one more http.Header parameter
• Add a new function which takes a mapper, a dialer and a handshaker and returns a dialer for gRPC

With the above changes, for your particular problem, you would just need to provide your mapper (which always returns your specified URL and http.Header field containing your creds), and build a dialer with the existing handshaker.

Please let us know if you want to make the implementation as we suggested.

If you don't have time to implement all of those and want a solution for your issue, a walkaround would be to implement your own proxy dialer, which may need copying some of the function from proxy.go, and dial using WithDialer.

[denchenko]

@dfawley no problem. I will implement it asap.

[menghanl]

Ping. Are you still planning on implementing this?

[denchenko]

@menghanl sorry for delay, I was on vacation. I am planning to implement this on Monday.

[menghanl]

@shevchenkodenis No worries! Thanks for implementing this!

[menghanl]

Ping. Just want to check what the status of this is.

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[menghanl]

Closing the PR now.
Please leave a comment if you want to revive this.