Compatibility between EnvHttpProxyAgent and DNS interceptor

[SuperOleg39]

Hello!

I have a question about EnvHttpProxyAgent and dns interceptor.

Can you help me to understand, how I can handle relation between this two features?

We have a custom setup with replacible default undici Agent, and extensible interceptors list, like this:

const agent = new Agent(options).compose(...(interceptors ?? []));

Then, we have separate http proxy module where default Agent is replaced, like this:

const agent = new EnvHttpProxyAgent({
    httpProxy: proxyEnv,
    httpsProxy: proxyEnv,
    noProxy: noProxyEnv,
    ...options,
  }).compose(...(interceptors ?? []));

The problem is, the same interceptors list is used, and DNS cache interceptor automatically passed into EnvHttpProxyAgent.compose list. After than, requests hostname is resolved to IP before proxy, and regular proxy env rules with hostnames can't be applied.

So, my question is more about how I need to treat relationship between this two:

• these features are mutually exclusive
• or I miss somethig and these features can work together?

[SuperOleg39]

On the one hand, I still want to cache DNS lookups for hosts from NO_PROXY list

[metcoder95]

By design coincidence, they are mutually exclusive, it was not meant to be like that from the beginning.

Nonetheless, sadly I'm unsure whereas a backtrack can be easily implemented. If this stills the desire, a intermediate interceptor can be added to do that explicit backtrack.

I can think of extending the dns interceptor to add a hint to the opaque object by adding the original DNS hostname instead of the resolved IP.

[SuperOleg39]

By design coincidence, they are mutually exclusive, it was not meant to be like that from the beginning.

Nonetheless, sadly I'm unsure whereas a backtrack can be easily implemented. If this stills the desire, a intermediate interceptor can be added to do that explicit backtrack.

I can think of extending the dns interceptor to add a hint to the opaque object by adding the original DNS hostname instead of the resolved IP.

Thanks for the answer!

Looks like for us, simple workaround to filter DNS interceptor before EnvHttpProxyAgent.compose should work.