Probably stupid question, but is it supposed to run via HTTPS? about appmetrics

[mattcolegate]

Hi @neilyoung,

appmetrics is designed to run alongside a Node.js application to provide monitoring information for that application. It doesn't matter to appmetrics if your application outputs to console, HTTP or HTTPS, it will run alongside just the same.
Information from appmetrics can be output by your application by utilising the monitoring.on function to obtain the monitoring data as an object (see https://github.com/RuntimeTools/appmetrics#modifying-your-application-to-use-appmetrics). Your application is then free to output that data in whatever form you wish.
If you are looking for something more visual in output, might I suggest https://github.com/runtimetools/appmetrics-dash ? It uses either your or it's own HTTP server to visually display data from appmetrics on a web dashboard.

[neilyoung]

If you are looking for something more visual in output, might I suggest https://github.com/runtimetools/appmetrics-dash ? It uses either your or it's own HTTP server to visually display data from appmetrics on a web dashboard.

This is what I'm using. And it just displays a screen full of empty field:

Setup like so:

(package.json):
"appmetrics-dash": "^5.3.0",
Then first line of my server code:

// Before all other 'require' statements
require('appmetrics-dash').attach()

As far as I know that was it.

My server is started like so:

var server = url.protocol === 'http:' ? http.createServer(app).listen(port, () => {
    logger.info('non-Secure server started  at %s', args.srv_url)
}) :
    https.createServer(options, app).listen(port, () => {
        logger.info('secure server started at %s', args.srv_url)
        http.createServer((req, res) => {
            res.writeHead(302, { 'location': 'https://' + req.headers.host + req.url })
            res.end()
        }).listen(80)
    })

A call to the dashboard route brings the above screen.

[mattcolegate]

That's interesting - there's code in appmetrics-dash to support both https and http servers - I wonder if it's being thrown off by your http redirect server? Does it work if you create a http server rather than a https server?

[neilyoung]

Will check later and let you know

[mattcolegate]

I threw together a quick sample HTTPS server and can confirm that appmetrics-dash appeared on https://localhost:3000/appmetrics-dash with meaningful data

test.js.txt

[mattcolegate]

I've now recreated your issue using your code snippet above - it looks like although the dashboard is available in both places data is only being sent to one of them. Your secure site's appmetrics-dash is empty, but your http redirect's one (on http://<host>:80/appmetrics-dash) is populated with data.

test.js.txt

To get your data going back where it should, you'll need to use the appmetrics-dash.monitor()method to just target your secure server - have a look at the following example to see what to do:

solution.js.txt

[neilyoung]

Cool. Thanks. As you said, it works via HTTPS, if I omit HTTP. Will try your latest suggestion now.
Having another problem on the same machine with another node server running at 8443, secure.

Same setup: First line the require statement. No HTTP server only HTTPS.

The first attempt to get the dashboard crashes the node server:

[Thu May 14 14:01:01 2020] com.ibm.diagnostics.healthcenter.loader INFO: Node Application Metrics 5.1.1.202005141355 (Agent Core 4.0.5)
[Thu May 14 14:01:02 2020] com.ibm.diagnostics.healthcenter.mqtt INFO: Connecting to broker localhost:1883
events.js:292
      throw er; // Unhandled 'error' event
      ^

Error [ERR_STREAM_WRITE_AFTER_END]: write after end
    at write_ (_http_outgoing.js:646:17)
    at ServerResponse.write (_http_outgoing.js:638:15)
    at ReadStream.ondata (_stream_readable.js:708:22)
    at ReadStream.emit (events.js:315:20)
    at ReadStream.EventEmitter.emit (domain.js:485:12)
    at addChunk (_stream_readable.js:297:12)
    at readableAddChunk (_stream_readable.js:273:9)
    at ReadStream.Readable.push (_stream_readable.js:214:10)
    at internal/fs/streams.js:242:14
    at /home/decades/awss-server/node_modules/async-listener/glue.js:188:31
Emitted 'error' event on ServerResponse instance at:
    at errorOrDestroy (internal/streams/destroy.js:128:12)
    at ServerResponse.onerror (_stream_readable.js:745:9)
    at ServerResponse.emit (events.js:327:22)
    at ServerResponse.EventEmitter.emit (domain.js:485:12)
    at writeAfterEndNT (_http_outgoing.js:701:7)
    at /home/decades/awss-server/node_modules/async-listener/glue.js:188:31
    at processTicksAndRejections (internal/process/task_queues.js:85:21) {
  code: 'ERR_STREAM_WRITE_AFTER_END'
}

Reproducible. With each attempt to access something.

[neilyoung]

OK, found it. I had to place the call to

dash.monitor({ server: server }) // Does not work yet

after all

app.thisandthat setups

[neilyoung]

Just one thing: There is a file resourceRegistry.log written by your plugin. Can this be omitted?

[mattcolegate]

Unfortunately at the moment it can't - it's generated automatically by one of our dependencies' dependencies. There is an open issue for it at IBM/node-ibmapm-restclient#5

[neilyoung]

Ok. Understand. What about authentication? Haven't found yet.

[mattcolegate]

Currently appmetrics-dash doesn't have built-in security such as authentication-based access. We do support the passing through of code to run when the endpoint is hit via <appmetrics-dash>.attach(options.middleware) or <application-dash>.monitor(options.middleware) so it should be possible to put a third-party security solution in place.

[neilyoung]

@mattcolegate May I ask you, what the mqtt broker thing does? Is it required to monitor the things, via the appmetrics-dash route?

Then: Is there a way to add own probes, like counters etc?

[mattcolegate]

MQTT http://mqtt.org/ is a transport mechanism that can be used by appmetrics to communicate with an MQTT broker, such as https://mosquitto.org/. It is not required to monitor things via the appmetrics-dash route.
You can certainly add your own probes - there is no official guide, but there are some pull requests that you can look at to get an idea of what to do.

[neilyoung]

OK, thanks. I don't need that. Can MQTT be disabled at all?

[mattcolegate]

Change com.ibm.diagnostics.healthcenter.mqtt=on to off in .../node_modules/appmetrics/appmetrics.properties

[neilyoung]

Cool. Thanks.