Add encode implementations for SocketAddr and IpAddr #87
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In general I am not opposed to this change. Though I would guess that in most cases, this is not what one wants. In case the number of unique IP addresses is large, this can easily lead to a cardinality explosion.
https://www.robustperception.io/cardinality-is-key/
What do you think of adding a warning doc comment to the implementations to make sure users are aware of what they are doing?
Also would you mind resolving the merge conflicts?
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Friendly ping @rnijveld. |
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@mxinden Sorry about the slow response, life got in the way a little. I definitely agree with not wanting to use this for high cardinality situations. Although of course such cases could happen just as easily with other label types, I do agree that IP addresses might more quickly result in a cardinality explosion when not used correctly. I've added a little warning text to each of the implementations, I hope that resolves your concerns, let me know if there's anything else I can do! |
| /// distinct values is low (i.e. low cardinality). In all other cases you should | ||
| /// combine your metrics into a single metric instead. Especially bad examples |
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In all other cases you should combine your metrics into a single metric instead.
I don't understand this. How is combining multiple metrics into one solving the issue of a cardinality explosion?
| /// distinct values is low (i.e. low cardinality). In all other cases you should | ||
| /// combine your metrics into a single metric instead. Especially bad examples |
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It is effectively never appropriate to use an address as a label, for reasons of cardinality already discussed. |
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I don't think "never" is correct. One use-case I can come up with is exposing ones listening address as an info metric. See e.g. kubernetes/kube-state-metrics#498 as an example on how far one can push cardinality in Prometheus with info metrics. |
Something I encounter quite often is having metrics based on connection information, so I frequently find myself wanting to use either a
SocketAddrorIpAddrin a label.