Automatically get body from koa-bodyparser

[watson]

If using the popular koa-bodyparser module, our captureBody config option currently doesn't have any effect. It would be nice if the agent natively supported extracting the body from this module. Either by getting it from ctx.request.body where it's stored by the koa-bodyparser, or by patching koa-bodyparser directly.

Fixes: elastic/apm-agent-nodejs#407

[watson]

We could instead consider getting the body directly from the request stream using https://github.com/watson/stream-observer

[Qard]

If we try to collect the request body with stream-observer we should make sure we have an escape condition decided for if the body gets too big.

[watson]

Yes. We already have an upper limit on 2048 bytes after which the body is truncated. We should respect that and just stop listening.

The stream-observer module returns a function which you can call at any time to stop listening for data.

[Qard]

Ah, cool. Sounds like it might be a good option then. :)

[ilionic]

Not sure it's related - if using koa-bodyparser getting GET unknown route

[Qard]

koa-bodyparser wouldn't cause that, but you'll currently only get routing information if you use koa-router. Using koa directly, or using other routing modules will not record a different transaction name. You can use agent.setTransactionName('custom name') if you want to provide a name yourself.

[imchao9]

@watson does this problem fix? If not fix, how to make the koa-bodyparser work? I try the

  captureBody: 'all',

I can not get the body information now.

[watson]

No, given the way koa-bodyparser work, we need to either patch it somehow or we need to hook in at a lower level. The way captureBody works currently is by expecting that the body is set as a property on the request object, either with the name req.body, req.json or req.payload. The koa-bodyparser module does not do that.

[imchao9]

No, given the way koa-bodyparser work, we need to either patch it somehow or we need to hook in at a lower level. The way captureBody works currently is by expecting that the body is set as a property on the request object, either with the name req.body, req.json or req.payload. The koa-bodyparser module does not do that.

And do we have any plan to make it work?

[watson]

Yes, that's why I created this issue. But it's not yet scheduled when it will be implemented.

To help us prioritize, could you share a little information on what your use-case for capturing the body is? Is it during the development phase of the application, or in a production environment? How large are the avg. bodies you want to capture, what's their content-type etc.

[imchao9]

Here is a demo

require('elastic-apm-node').start({
  // Override service name from package.json
  // Allowed characters: a-z, A-Z, 0-9, -, _, and space
  serviceName: 'helloworld',

  // Use if APM Server requires a token
  secretToken: '',

  // Set custom APM Server URL (default: http://localhost:8200)
  serverUrl: 'http://localhost:8200',
  logLevel: 'trace',
  asyncHooks: false,
  captureHeaders: true,
  captureBody: 'all',
  errorOnAbortedRequests: true,
  abortedErrorThreshold: true,
  transactionSampleRate: '1.0',

});

const Koa = require('koa');
const Router = require('koa-router');
const request = require('superagent');

const app = new Koa();
const router = new Router();

router.get('/tt', async (ctx, next) => {
  const response = await request.get('https://petstore.swagger.io/v2/store/inventory');
  ctx.body = response.body;
})

app.use(router.routes())
  .use(router.allowedMethods());

app.use(async ctx => {
  ctx.req.body = ctx.request.body
})

app.listen(3000);

[Qard]

@watson We should probably just capture the body from the raw-body module. As far as I know, every body parser uses it.

[sibelius]

so no request body neither response body are recorded into apm?

[sibelius]

where is the best place to add a test to this ?