Promote confmap.strictlyTypedInput feature gate to beta (#10554)

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

Makes type resolution strict and conforming to the behavior described in
[the env vars
RFC](https://github.com/open-telemetry/opentelemetry-collector/blob/main/docs/rfcs/env-vars.md)

Depends on:

- #10553
- #10555
- #10559
- open-telemetry/opentelemetry-collector-contrib/pull/33950

<!-- Issue number if applicable -->
#### Link to tracking issue
Fixes #9532, Fixes #8565

---------

Co-authored-by: Alex Boten <[email protected]>

Author: mx-psi

.chloggen/mx-psi_enable-strict-types.yaml

@@ -0,0 +1,29 @@
+# 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. otlpreceiver)
+component: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Promote `confmap.strictlyTypedInput` feature gate to beta.
+
+# One or more tracking issues or pull requests related to the change
+issues: [10552]
+
+# (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: | 
+  This feature gate changes the following:
+  - Configurations relying on the implicit type casting behaviors listed on [#9532](https://github.com/open-telemetry/opentelemetry-collector/issues/9532) will start to fail.
+  - Configurations using URI expansion (i.e. `field: ${env:ENV}`) for string-typed fields will use the value passed in `ENV` verbatim without intermediate type casting.
+
+
+# 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: []

confmap/expand_test.go

@@ -551,18 +551,18 @@ func TestResolverExpandUnsupportedScheme(t *testing.T) {
 
 func TestResolverExpandStringValueInvalidReturnValue(t *testing.T) {
 	provider := newFakeProvider("input", func(context.Context, string, WatcherFunc) (*Retrieved, error) {
-		return NewRetrieved(map[string]any{"test": "localhost:${test:PORT}"})
+		return NewRetrievedFromYAML([]byte(`test: "localhost:${test:PORT}"`))
 	})
 
 	testProvider := newFakeProvider("test", func(context.Context, string, WatcherFunc) (*Retrieved, error) {
-		return NewRetrieved([]any{1243})
+		return NewRetrievedFromYAML([]byte("[1243]"))
 	})
 
 	resolver, err := NewResolver(ResolverSettings{URIs: []string{"input:"}, ProviderFactories: []ProviderFactory{provider, testProvider}, ConverterFactories: nil})
 	require.NoError(t, err)
 
 	_, err = resolver.Resolve(context.Background())
-	assert.EqualError(t, err, `expanding ${test:PORT}: expected convertable to string value type, got ['ӛ']([]interface {})`)
+	assert.EqualError(t, err, `expanding ${test:PORT}: retrieved value does not have unambiguous string representation: [1243]`)
 }
 
 func TestResolverDefaultProviderExpand(t *testing.T) {

confmap/internal/e2e/types_test.go

@@ -132,6 +132,14 @@ func TestTypeCasting(t *testing.T) {
 		},
 	}
 
+	previousValue := featuregates.StrictlyTypedInputGate.IsEnabled()
+	err := featuregate.GlobalRegistry().Set(featuregates.StrictlyTypedInputID, false)
+	require.NoError(t, err)
+	defer func() {
+		err := featuregate.GlobalRegistry().Set(featuregates.StrictlyTypedInputID, previousValue)
+		require.NoError(t, err)
+	}()
+
 	for _, tt := range values {
 		t.Run(tt.value+"/"+string(tt.targetField), func(t *testing.T) {
 			testFile := "types_expand.yaml"

exporter/otlpexporter/testdata/config.yaml

@@ -18,7 +18,7 @@ auth:
   authenticator: nop
 headers:
   "can you have a . here?": "F0000000-0000-0000-0000-000000000000"
-  header1: 234
+  header1: "234"
   another: "somevalue"
 keepalive:
   time: 20s

exporter/otlphttpexporter/testdata/config.yaml

@@ -20,6 +20,6 @@ retry_on_failure:
   max_elapsed_time: 10m
 headers:
   "can you have a . here?": "F0000000-0000-0000-0000-000000000000"
-  header1: 234
+  header1: "234"
   another: "somevalue"
 compression: gzip

internal/featuregates/featuregates.go

@@ -13,7 +13,7 @@ var UseUnifiedEnvVarExpansionRules = featuregate.GlobalRegistry().MustRegister("
 const StrictlyTypedInputID = "confmap.strictlyTypedInput"
 
 var StrictlyTypedInputGate = featuregate.GlobalRegistry().MustRegister(StrictlyTypedInputID,
-	featuregate.StageAlpha,
+	featuregate.StageBeta,
 	featuregate.WithRegisterFromVersion("v0.103.0"),
 	featuregate.WithRegisterDescription("Makes type casting rules during configuration unmarshaling stricter. See https://github.com/open-telemetry/opentelemetry-collector/blob/main/docs/rfcs/env-vars.md for more details."),
 )

otelcol/unmarshaler_test.go

@@ -128,7 +128,7 @@ func TestPipelineConfigUnmarshalError(t *testing.T) {
 					},
 				},
 			}),
-			expectError: "'[traces].receivers[0]' has invalid keys: nop",
+			expectError: "'[traces].receivers': source data must be an array or slice, got map",
 		},
 	}