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Add pprof endpoints if enabled in configuration #1017

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@jonaz jonaz commented Nov 6, 2024

To help troubleshoot future leaks in production.

@evrardjp
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evrardjp commented Nov 6, 2024

I guess that's better than rebuilding... Ok will test it. The GET feels a bit awkward compared to using mux handler, but that's definitely a nit. Let me test that.

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jonaz commented Nov 6, 2024

I guess that's better than rebuilding... Ok will test it. The GET feels a bit awkward compared to using mux handler, but that's definitely a nit. Let me test that.

I just copy pasted the pprof init function in std. Dont want it to always be enabled.
The method (GET) pattern is new in 1.21 i think it was. Docs: https://pkg.go.dev/net/http#ServeMux

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If it's always enabled, we don't need the handleFunc. Are you sure this can be disabled, or did I test wrong?

@@ -278,6 +281,9 @@ func main() {
go rebootAsRequired(nodeID, rebooter, rebootChecker, window, lock, client)
go maintainRebootRequiredMetric(nodeID, rebootChecker)

if pprofEnabled {
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I don't think this works: while pprofEnabled is by defaut to false, the net/http/pprof is still loaded, so it's still injecting itself?

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Oh yeah.. 🤦

i guess we could just import _ "net/http/pprof" and leave it enabled.
Or use a custom mux and not the DefaultServeMux where we can conditionally enable it.

Which do you like?

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I don't know yet... Do we really need to have this enabled at all times? For me we do not... And we do not have to flip the switch live on a build. I don't mind continuing to add import _ "net/http/pprof" line when necessary.

For me the valid question is not about whether we do have profiling, but rather "who is checking the profiling before release". yet I wouldn't mind to make the life easier of the person who will need it. Just not sure how yet.

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Pprof is normally enabled on all services and its because all kind of leaks can be hard to reproduce and then we can just check the pprof endpoint in production when needed.

I'll update the PR to default to off with another mux and then we can in our deployment always enable it like almost all our other pods.

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Pprof is normally enabled on all services and its because all kind of leaks can be hard to reproduce and then we can just check the pprof endpoint in production when needed.

If I follow your point, we would just add import _ "net/http/pprof" then. However I don't think it's a good idea, it's been the cause of cves in the past. GHSA-9frv-h2cf-52wh

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Yeah that's why I would like it default off but on for all our hundreds of instances.

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2 participants