[otelcol] Add mapstructure tags to main Config struct (open-telemetry…

…#10152)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Adds `mapstructure` tags to main `Config` struct.

cc @mackjmr

.chloggen/mx-psi_add-mapstructure-labels.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: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: otelcol
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add explicit mapstructure tags to main configuration struct
+
+# One or more tracking issues or pull requests related to the change
+issues: [10152]
+
+# (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: [api]

otelcol/config.go

@@ -20,21 +20,21 @@ var (
 // Config defines the configuration for the various elements of collector or agent.
 type Config struct {
 	// Receivers is a map of ComponentID to Receivers.
-	Receivers map[component.ID]component.Config
+	Receivers map[component.ID]component.Config `mapstructure:"receivers"`
 
 	// Exporters is a map of ComponentID to Exporters.
-	Exporters map[component.ID]component.Config
+	Exporters map[component.ID]component.Config `mapstructure:"exporters"`
 
 	// Processors is a map of ComponentID to Processors.
-	Processors map[component.ID]component.Config
+	Processors map[component.ID]component.Config `mapstructure:"processors"`
 
 	// Connectors is a map of ComponentID to connectors.
-	Connectors map[component.ID]component.Config
+	Connectors map[component.ID]component.Config `mapstructure:"connectors"`
 
 	// Extensions is a map of ComponentID to extensions.
-	Extensions map[component.ID]component.Config
+	Extensions map[component.ID]component.Config `mapstructure:"extensions"`
 
-	Service service.Config
+	Service service.Config `mapstructure:"service"`
 }
 
 // Validate returns an error if the config is invalid.