[cmd/opampsupervisor] log stderr using Error (#40491)

#### Description

This seems like a bug, but it is also a breaking change. The logger used
when logging errors from the collector was always logging messages with
a severity of Info, even for messages from the stderr pipe.

---------

Signed-off-by: alex boten <[email protected]>
Co-authored-by: Tyler Helmuth <[email protected]>
Co-authored-by: Antoine Toulme <[email protected]>

Author: 3 people

.chloggen/codeboten_log-stderr-to-error.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: opampsupervisor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Update passthrough logging to use Error for stderr pipe.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [40491]
+
+# (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:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# 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: []

cmd/opampsupervisor/supervisor/commander/commander.go

@@ -157,7 +157,7 @@ func (c *Commander) startWithPassthroughLogging() error {
 		scanner := bufio.NewScanner(stderrPipe)
 		for scanner.Scan() {
 			line := scanner.Text()
-			colLogger.Info(line)
+			colLogger.Error(line)
 		}
 		if err := scanner.Err(); err != nil {
 			c.logger.Error("Error reading agent stderr: %w", zap.Error(err))

cmd/opampsupervisor/supervisor/config/config.go

@@ -237,8 +237,9 @@ type Telemetry struct {
 }
 
 type Logs struct {
-	Level       zapcore.Level `mapstructure:"level"`
-	OutputPaths []string      `mapstructure:"output_paths"`
+	Level            zapcore.Level `mapstructure:"level"`
+	ErrorOutputPaths []string      `mapstructure:"error_output_paths"`
+	OutputPaths      []string      `mapstructure:"output_paths"`
 	// Processors allow configuration of log record processors to emit logs to
 	// any number of supported backends.
 	Processors []config.LogRecordProcessor `mapstructure:"processors,omitempty"`
@@ -288,8 +289,9 @@ func DefaultSupervisor() Supervisor {
 		},
 		Telemetry: Telemetry{
 			Logs: Logs{
-				Level:       zapcore.InfoLevel,
-				OutputPaths: []string{"stderr"},
+				Level:            zapcore.InfoLevel,
+				OutputPaths:      []string{"stdout"},
+				ErrorOutputPaths: []string{"stderr"},
 			},
 		},
 	}

cmd/opampsupervisor/supervisor/config/config_test.go

@@ -541,6 +541,7 @@ agent:
 telemetry:
   logs:
     level: warn
+    error_output_paths: ["stderr"]
     output_paths: ["stdout"]
 `
 				config = fmt.Sprintf(config, filepath.Join(tmpDir, "storage"), executablePath)
@@ -584,8 +585,9 @@ telemetry:
 					},
 					Telemetry: Telemetry{
 						Logs: Logs{
-							Level:       zapcore.WarnLevel,
-							OutputPaths: []string{"stdout"},
+							Level:            zapcore.WarnLevel,
+							OutputPaths:      []string{"stdout"},
+							ErrorOutputPaths: []string{"stderr"},
 						},
 					},
 				}

cmd/opampsupervisor/supervisor/supervisor_test.go

@@ -534,6 +534,10 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths:
+                - stderr
+            output_paths:
+                - stdout
         resource: null
 `
 
@@ -630,6 +634,10 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths:
+                - stderr
+            output_paths:
+                - stdout
         resource: null
 `
 
@@ -793,6 +801,10 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths:
+                - stderr
+            output_paths:
+                - stdout
         resource: null
 `
 
@@ -1494,6 +1506,10 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths:
+                - stderr
+            output_paths:
+                - stdout
             processors:
                 - batch:
                     exporter:

cmd/opampsupervisor/supervisor/templates/extraconfig.yaml

@@ -3,6 +3,10 @@ service:
     logs:
       # Enables JSON log output for the Agent.
       encoding: json
+      # Ensure logs and errors are using the correct output
+      # channel
+      error_output_paths: ["stderr"]
+      output_paths: ["stdout"]
     resource:
       # Set resource attributes suggested by the OpAMP spec.
       # See https://github.com/open-telemetry/opamp-spec/blob/main/specification.md#agentdescription-message

cmd/opampsupervisor/supervisor/testdata/merged_effective_config.yaml

@@ -44,5 +44,7 @@ service:
   telemetry:
     logs:
       encoding: json
+      error_output_paths: ["stderr"]
+      output_paths: ["stdout"]
     resource:
       service.name: otelcol

cmd/opampsupervisor/supervisor/testdata/merged_local_config.yaml

@@ -33,5 +33,7 @@ service:
   telemetry:
     logs:
       encoding: json
+      error_output_paths: ["stderr"]
+      output_paths: ["stdout"]
     resource:
       service.name: otelcol

cmd/opampsupervisor/testdata/collector/effective_config.yaml

@@ -37,5 +37,7 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths: ["stderr"]
+            output_paths: ["stdout"]
         resource:
             service.name: otelcol

cmd/opampsupervisor/testdata/collector/effective_config_without_extensions.yaml

@@ -35,5 +35,7 @@ service:
     telemetry:
         logs:
             encoding: json
+            error_output_paths: ["stderr"]
+            output_paths: ["stdout"]
         resource:
             service.name: otelcol