prom-client 11.2.0 breaks middleware

[peterkuiper]

When running the latest version of prom-client these metrics disappear:

# HELP up 1 = up, 0 = not up
# TYPE up gauge
up 1

# HELP http_request_duration_seconds duration histogram of http responses labeled with: status_code, method, path
# TYPE http_request_duration_seconds histogram

I haven't had the time to figure out what is new in prom-client. I have set the version to 11.1.3 as a quick fix.

[disjunction]

hm, that's unfortunate. Minor versions should normally be backwards-compatible, and this lib is quite straight-forward in what it does. Thanks for reporting it!

[disjunction]

I couldn't reproduce this problem. It works fine for me.

I suspect there is a misunderstanding. Bare in mind: express-prom-bundle has a direct dependency on prom-client. When you were testing it it was ~11.1.2, thus you COULD NOT use 11.2.0 at all unless you meddled with the library. Since today release I upgraded the dependency to ~11.2.1

If you have prom-client@11.2.0 installed in your app separately, then in your app you actually have 2 different prom-client instances, one which came with express-prom-bundle, and another - your own. They don't share the metrics, so it might be you were collecting the data with one client, while trying to read from another one.

Until now you could use a workaround: instead of installing and requiring prom-client, you could directly access the one, coming with express-prom-bundle as follows:

const promClient = require('express-prom-bundle').promClient

With the new release 5.x prom-client will become a peer dependency and you won't have this problem again.

Please reopen if my guess is wrong and you still experience the problem, in which case I'd need some reproducible test case.