[configtelemetry] add guidelines for each level of config telemetry (#…

…10365)

#### Description
Add to the package comment a set of guidelines for configtelemetry
levels.

#### Link to tracking issue
Fixes #10286

---------

Co-authored-by: Dmitrii Anoshin <[email protected]>
Co-authored-by: Tyler Helmuth <[email protected]>
Co-authored-by: Alex Boten <[email protected]>

.chloggen/add_guidelines_telemetry.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: configtelemetry
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add guidelines for each level of component telemetry
+
+# One or more tracking issues or pull requests related to the change
+issues: [10286]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

config/configtelemetry/doc.go

@@ -4,4 +4,44 @@
 // Package configtelemetry defines various telemetry level for configuration.
 // It enables every component to have access to telemetry level
 // to enable metrics only when necessary.
+//
+// This document provides guidance on which telemetry level to adopt for Collector metrics.
+// When adopting a telemetry level, component authors are expected to rely on this guidance to
+// justify their choice of telemetry level.
+//
+// 1. configtelemetry.None
+//
+// No telemetry data is recorded.
+//
+// 2. configtelemetry.Basic
+//
+// Telemetry associated with this level provides essential coverage of the collector telemetry.
+// It should only be used for internal collector telemetry generated by the collector core API. Components outside of
+// the core API MUST NOT record additional telemetry at this level.
+//
+// 3. configtelemetry.Normal
+//
+// Telemetry associated with this level provides complete coverage of the collector telemetry.
+// It should be the default for component authors.
+//
+// Component authors using this telemetry level can use this guidance:
+//
+//   - The signals associated with this level must control cardinality.
+//     It is acceptable at this level for cardinality to scale linearly with the monitored resources.
+//
+//   - The signals associated with this level must represent a controlled data volume. Examples follow:
+//
+//     a. A max cardinality (total possible combinations of dimension values) for a given metric of at most 100.
+//
+//     b. At most 5 spans actively recording simultaneously per active request.
+//
+// This is the default level recommended when running the Collector.
+//
+// 4. configtelemetry.Detailed
+//
+// Telemetry associated with this level provides complete coverage of the collector telemetry.
+//
+// The signals associated with this level may exhibit high cardinality and/or high dimensionality.
+//
+// There is no limit on data volume.
 package configtelemetry // import "go.opentelemetry.io/collector/config/configtelemetry"