TargetAllocator hash computation returning false negative

[rashmichandrashekar]

I am seeing hash computation issue for regex field where it returns a false negative, when there is only change in the regex field here -

opentelemetry-operator/cmd/otel-allocator/target/discovery.go

Line 85 in 56f5de9

hash, err := hashstructure.Hash(jobToScrapeConfig, nil)

For example, when there are 2 scrape configs with just the regex field changed between the 2, the hash returned is the same.

scrape_configs:
  - job_name: kube-proxy
    scrape_interval: 30s
    label_limit: 63
    label_name_length_limit: 511
    label_value_length_limit: 1023
    kubernetes_sd_configs:
    - role: pod
    relabel_configs:
    - action: keep
      source_labels:
      - __meta_kubernetes_namespace
      - __meta_kubernetes_pod_name
      separator: "/"
      regex: kube-system/kube-proxy.+
    - source_labels:
      - __address__
      action: replace
      target_label: __address__
      regex: "regex1"
      replacement: "$$1:10249"

scrape_configs:
  - job_name: kube-proxy
    scrape_interval: 30s
    label_limit: 63
    label_name_length_limit: 511
    label_value_length_limit: 1023
    kubernetes_sd_configs:
    - role: pod
    relabel_configs:
    - action: keep
      source_labels:
      - __meta_kubernetes_namespace
      - __meta_kubernetes_pod_name
      separator: "/"
      regex: kube-system/kube-proxy.+
    - source_labels:
      - __address__
      action: replace
      target_label: __address__
      regex: "regex2"
      replacement: "$$1:10249"

These 2 configs return the same hash

[rashmichandrashekar]

Similar to issue - #1358

[swiatekm]

Fixed by #2171

[rashmichandrashekar]

@swiatekm-sumo - Sorry for the delay in responding to this issue as there seems to be a fix made with this - #2171
But, the fix is only partial because, if the same fix isn't made to the otel collector's prometheusreceiver, even though the hash computation here fixes the relabeling for targets, the collector fails to get the updated config and will not work e2e as expected for metric relabeling. The same fix needs to be made here
Are there any plans to make this change in the otel collector repo?

[swiatekm]

@rashmichandrashekar you should open an issue in the contrib repo and reference this one. Looks like a simple enough fix in the receiver - thanks for pointing this out!

[rashmichandrashekar]

@rashmichandrashekar you should open an issue in the contrib repo and reference this one. Looks like a simple enough fix in the receiver - thanks for pointing this out!

Thanks @swiatekm-sumo - I have created an issue here - open-telemetry/opentelemetry-collector-contrib#29313