Use Case

I use outputs.prometheus_client plugin to expose metrics for Prometheus to scrape. In my current setup, the collected metrics contain UTF-8 text in metric names or label names.

As of now, Prometheus 3.0 has explicitly added support for UTF-8 metric names and label names (https://prometheus.io/docs/guides/utf8/).

I would like the outputs.prometheus_client plugin also support exporting UTF-8 encoded metric names and label names, so that its behavior aligns with the current capabilities of Prometheus.

Expected behavior

Given that Prometheus 3.0 already supports UTF-8, when using the outputs.prometheus_client plugin to expose metrics over HTTP, I expect that:

• Telegraf can accept UTF-8 encoded metric names and label names
• These UTF-8 names are exposed correctly in the Prometheus exposition output

Actual behavior

[[outputs.prometheus_client]]
  listen = ":9273"
  path = "/metrics"
  metric_version = 2
  expiration_interval = "5m"

Input

# metrics.lp
metric_ch_tag,中文标签=alpha value=1
metric_ch_tag_value,tag=中文 value=1
metric_ch_field,tag=alpha 中文字段=1

Output

# HELP metric_ch_field Telegraf collected metric
# TYPE metric_ch_field untyped
metric_ch_field{host="host_xxx",tag="alpha"} 1

# HELP metric_ch_tag_value Telegraf collected metric
# TYPE metric_ch_tag_value untyped
metric_ch_tag_value{host="host_xxx"} 1

# HELP metric_ch_tag_value_value Telegraf collected metric
# TYPE metric_ch_tag_value_value untyped
metric_ch_tag_value_value{host="host_xxx",tag="中文"} 1

In the current version of outputs.prometheus_client, even though Prometheus 3.0 supports UTF-8, when metric names or label names contain non-ASCII characters:

• The plugin still applies sanitization during the serialization stage
• Non-ASCII UTF-8 characters are replaced or filtered out
• The exposed metric names or label names no longer match the original data

Additional info

I have already implemented UTF-8 support for metric names and label names based on the current outputs.prometheus_client plugin, and I would like to contribute to the development of this feature.