prometheus_scrape source's query doesn't add the [] to mapping list

[valleedelisle]

A note for the community

• Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
• If you are interested in working on this issue or have submitted a pull request, please leave a comment

Problem

Result:

2024-12-18T03:55:00.342027Z DEBUG source{component_kind="source" component_id=src-metrics-prod-proxy component_type=prometheus_scrape}:http: vector::internal_events::http_client: Sending HTTP request. uri=https://myprometheus/federate?match=%7Bjob%3D%something%22%7D method=GET version=HTTP/1.1 headers={"accept": "text/plain", "user-agent": "Vector/0.43.1 (x86_64-unknown-linux-musl e30bf1f 2024-12-10 16:14:47.175528383)", "accept-encoding": "identity"} body=[empty]

Configuration

Sample config:


      src-metrics-prod-proxy:
        endpoints:
        - "https://myprometheus/federate"
        honor_labels: true
        scrape_interval_secs: 60
        scrape_timeout_secs: 45
        query:
          match:
            - '{job="something"}'
        tls:
          verify_certificate: false
          verify_hostname: false
        type: prometheus_scrape

Version

vector 0.43.1 (x86_64-unknown-linux-musl e30bf1f 2024-12-10 16:14:47.175528383)

Debug Output

No response

Example Data

No response

Additional Context

No response

References

No response

[jszwedko]

HI @valleedelisle !

I think I'm missing the issue here. Could you describe the expected behavior?

[valleedelisle]

Sorry, I should have clarified this.

Prometheus is expecting a url like this:
https://myprometheus/federate?match[]=%7Bjob%3D%something%22%7D

As opposed to this:
https://myprometheus/federate?match=%7Bjob%3D%something%22%7D

[jszwedko]

Ah I see. It's curious that this issue hasn't been reported before. That match feature has been there for quite a while 🤔

[sainad2222]

I tried by modifying your source config to include [] after match, something like this and it's working after that

Sample config:


      src-metrics-prod-proxy:
        endpoints:
        - "https://myprometheus/federate"
        honor_labels: true
        scrape_interval_secs: 60
        scrape_timeout_secs: 45
        query:
          match[]:
            - '{job="something"}'
        tls:
          verify_certificate: false
          verify_hostname: false
        type: prometheus_scrape

But if we want to make it easier, I created a PR to replace match key with match[] at source while building url

[pront]

Looking at our example:

fn query_example() -> serde_json::Value {
    serde_json::json! ({
        "match[]": [
            "{job=\"somejob\"}",
            "{__name__=~\"job:.*\"}"
        ]
    })
}

...this looks like a configuration issue, replacing this:

query:
  match:
    - '{job="something"}'

with this:

query:
  match[]:
    - '{job="something"}'

should fix it.

[jszwedko]

Agreed, I think what @pront shared is the way to do this, currently, with Vector. We have another issue tracking improvements to query string generation that will make this more straight-forward: #12073. I'll close this one, but feel free to follow along on the other.