docs: add redpanda_trust_file_crc32c and redpanda_truststore_expires_at_timestamp_seconds metrics

[paulohtb6]

Description

Resolves https://redpandadata.atlassian.net/browse/DOC-177
Review deadline: 28th July

Page previews

• redpanda_trust_file_crc32c

• redpanda_truststore_expires_at_timestamp_seconds

Checks

• New feature
• Content gap
• Support Follow-up
• Small fix (typos, links, copyedits, etc)

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📝 Walkthrough

Walkthrough

Two new public metrics have been added to the documentation in the TLS metrics section. The first metric, redpanda_trust_file_crc32c, is a gauge that reports the CRC32C checksum of trust file contents, with labels for aggregates, label, and shard. The second metric, redpanda_truststore_expires_at_timestamp_seconds, is a gauge that indicates the expiration time of the shortest-lived certificate authority in the truststore, with labels for aggregates, label, and label_instance. Both metrics are documented immediately before the existing redpanda_wasm_engine_cpu_seconds_total metric.

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Actionable comments posted: 1

📜 Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 74e059e and abdeb27.

📒 Files selected for processing (1)

• modules/reference/pages/public-metrics-reference.adoc (1 hunks)

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🔇 Additional comments (2)

modules/reference/pages/public-metrics-reference.adoc (2)

1895-1899: Label set diverges from established TLS metric conventions

Existing TLS metrics use area and detail labels, e.g. redpanda_tls_certificate_valid.
The newly added gauges introduce aggregates, label, and shard (and label_instance). Unless the exporter really emits these label names, this creates inconsistent cardinality and increases PromQL boilerplate.

Confirm the authoritative label list emitted by Redpanda and harmonise with the earlier TLS metrics.

---

1903-1908: Clarify duplicate metric entry and update documentation accordingly

There are two seemingly identical gauges in modules/reference/pages/public-metrics-reference.adoc:

• Line 1782: redpanda_tls_truststore_expires_at_timestamp_seconds
• Line 1903: redpanda_truststore_expires_at_timestamp_seconds

Please confirm with the owning team or by inspecting the exporter code which metric name is actually emitted. Then choose one of the following:

• If the metric has been renamed to drop tls_, mark the old name deprecated (with removal timeline) and update its documentation accordingly.
• If the new entry was added by mistake, delete it to avoid duplicate documentation.

[oleiman]

lgtm

[micheleRP]

lgtm