Use component.StabilityLevel for entity stability (#14425)

Right now, the entity is using `string` for its stability field, which
prevents validating that the value is within the enum.
This changes it to a `component.StabilityLevel`.

---------

Co-authored-by: Alex Boten <223565+codeboten@users.noreply.github.com>

Author: dmathieu

.chloggen/validate-entity-stability.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. receiver/otlp)
+component: cmd/mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Validate stability level for entities
+
+# One or more tracking issues or pull requests related to the change
+issues: [14425]
+
+# (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: []

cmd/mdatagen/internal/metadata.go

@@ -11,6 +11,7 @@ import (
 	"strconv"
 	"strings"
 
+	"go.opentelemetry.io/collector/component"
 	"go.opentelemetry.io/collector/filter"
 	"go.opentelemetry.io/collector/pdata/pcommon"
 )
@@ -628,7 +629,7 @@ type Entity struct {
 	// Brief is a brief description of the entity.
 	Brief string `mapstructure:"brief"`
 	// Stability is the stability level of the entity.
-	Stability string `mapstructure:"stability"`
+	Stability component.StabilityLevel `mapstructure:"stability"`
 	// Identity contains references to resource attributes that uniquely identify the entity.
 	Identity []EntityAttributeRef `mapstructure:"identity"`
 	// Description contains references to resource attributes that describe the entity.

cmd/mdatagen/internal/metadata_test.go

@@ -140,6 +140,10 @@ func TestValidate(t *testing.T) {
 			name:    "testdata/entity_duplicate_types.yaml",
 			wantErr: `duplicate entity type: host`,
 		},
+		{
+			name:    "testdata/invalid_entity_stability.yaml",
+			wantErr: `unsupported stability level: "stable42"`,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

cmd/mdatagen/internal/sampleconnector/documentation.md

@@ -137,7 +137,7 @@ The following entities are defined for this component:
 
 A test entity.
 
-**Stability:** stable
+**Stability:** Stable
 
 **Identifying Attributes:**
 - `string.resource.attr`

cmd/mdatagen/internal/testdata/invalid_entity_stability.yaml

@@ -0,0 +1,28 @@
+type: sample
+status:
+  class: receiver
+  stability:
+    stable: [metrics]
+
+resource_attributes:
+  host.id:
+    description: The unique host identifier
+    type: string
+    enabled: true
+  host.name:
+    description: The hostname
+    type: string
+    enabled: true
+  process.pid:
+    description: The process identifier
+    type: int
+    enabled: true
+
+entities:
+  - type: host
+    brief: A host instance.
+    stability: stable42
+    identity:
+      - ref: host.id
+    description:
+      - ref: host.name