dnscrypt_proxy_build_info in prometheus export is malformed

[memoz]

Hi all,

I tried scraping dnscrypt-proxy's prometheus export using telegraf, but it complained about:
[inputs.prometheus] Error in plugin: error reading metrics for "https://127.0.0.1:8080/metrics": decoding response failed: text format parsing error in line 3: unexpected end of label value "arm64"

Upon closer inspection, this is the offending line:
dnscrypt_proxy_build_info{goarch="arm64" goos="linux" goversion="go1.26.0" version="2.1.15"} 1

It's not following label_pairs = label_pair { "," label_pair } [ "," ] syntax as shown here: https://prometheus.io/docs/instrumenting/exposition_formats/

The correct output should be:
dnscrypt_proxy_build_info{goarch="arm64",goos="linux",goversion="go1.26.0",version="2.1.15"} 1.

[memoz]

Here's my workaround until this is fixed if anyone's interested:

[[inputs.http]]
  urls = ["https://127.0.0.1:8080/metrics"]
  username = "your_username"
  password = "your_password"
  tls_server_name = "example.com" 
  data_format = "value"
  data_type = "string"
  tags = { raw_format = "dnscrypt_fix" }


[[processors.starlark]]
  order = 1
  tagpass = ["raw_format"]
  
source = '''
def apply(metric):
    raw_data = metric.fields.get("value")
    if not raw_data:
        return metric
    lines = raw_data.split('\n')
    for i in range(len(lines)):
        if lines[i].startswith("dnscrypt_proxy_build_info"):
            lines[i] = lines[i].replace('" ', '",')
            break
    fixed = '\n'.join(lines)
    if not fixed.endswith('\n'):
        fixed += '\n'
    metric.fields["value"] = fixed
    return metric
'''


[[processors.parser]]
  order = 2
  tagpass = ["raw_format"]
  parse_fields = ["value"]
  data_format = "prometheus"
  drop_original = true

[welwood08]

I believe this issue was already fixed 2 weeks ago in 95c695a and will be in the next release.