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Also forward error requests to the proxy #2425

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Merged
merged 1 commit into from
Feb 5, 2020
Merged

Also forward error requests to the proxy #2425

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8 changes: 6 additions & 2 deletions lib/Server.js
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Original file line number Diff line number Diff line change
Expand Up @@ -288,7 +288,7 @@ class Server {
this.websocketProxies.push(proxyMiddleware);
}

this.app.use((req, res, next) => {
const handle = (req, res, next) => {
if (typeof proxyConfigOrCallback === 'function') {
const newProxyConfig = proxyConfigOrCallback();

Expand Down Expand Up @@ -319,7 +319,11 @@ class Server {
} else {
next();
}
});
};

this.app.use(handle);
// Also forward error requests to the proxy so it can handle them.
this.app.use((error, req, res, next) => handle(req, res, next));
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It is create two instances of proxy that was reduce performance
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@OliverJAsh OliverJAsh Feb 3, 2020 •
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The proxy middleware is created once, outside of handle:

 proxyMiddleware = getProxyMiddleware(proxyConfig);

… and the result is used in handle on each request, be it a non-error or error request. So I don't think this change will hurt performance in any way.

If you really think this will hurt performance, are you able to provide an example to demonstrate that's the case?
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Each request now run handle (

webpack-dev-server/lib/Server.js

Line 291 in 29a822e

const handle = (req, res, next) => {
) twice so we potentially send require to middleware twice

webpack-dev-server/lib/Server.js

Line 318 in 29a822e

return proxyMiddleware(req, res, next);

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I don't believe that's true. handle will only run once:

  • If the request has not errored, handle will be called via app.use(handle).
  • If the request has errored, handle will be called via app.use((error, req, res, next) => handle(req, res, next)).

You can see this for yourself if you add some logging to handle.
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Hm, looks you are right https://expressjs.com/en/guide/error-handling.html
});
}

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17 changes: 17 additions & 0 deletions test/server/proxy-option.test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -326,6 +326,19 @@ describe('proxy option', () => {
// Parse application/json
proxy.use(bodyParser.json());

// This forces Express to try to decode URLs, which is needed for the test
// associated with the middleware below.
proxy.all('*', (_req, res, next) => {
next();
});
// We must define all 4 params in order for this to be detected as an
// error handling middleware.
// eslint-disable-next-line no-unused-vars
proxy.use((error, proxyReq, res, next) => {
res.status(500);
res.send('error from proxy');
});

proxy.get('/get', (proxyReq, res) => {
res.send('GET method from proxy');
});
Expand Down Expand Up @@ -372,6 +385,10 @@ describe('proxy option', () => {
});
});

it('errors', (done) => {
req.get('/%').expect(500, 'error from proxy', done);
});

it('GET method', (done) => {
req.get('/get').expect(200, 'GET method from proxy', done);
});
Expand Down