[confmap] Add strict type validation under a feature gate (#10400)

#### Description

<!-- Issue number if applicable -->

- Add `confmap.strictlyTypedInput` feature gate that introduces stricter
type checks when resolving configuration
- Make `confmap.NewRetrievedFromYAML` function public so that external
providers have consistent behavior when resolving YAML
- Adds `confmap.Retrieved.AsString` method to retrieve string
representation for retrieved values

#### Link to tracking issue

Relates to #9854, updates #8565, #9532

Author: mx-psi

.chloggen/mx-psi_asstring.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: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds `confmap.Retrieved.AsString` method that returns the configuration value as a string"
+
+# One or more tracking issues or pull requests related to the change
+issues: [9532]
+
+# (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]

.chloggen/mx-psi_newretrievedfromyaml.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: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds `confmap.NewRetrievedFromYAML` helper to create `confmap.Retrieved` values from YAML bytes"
+
+# One or more tracking issues or pull requests related to the change
+issues: [9532]
+
+# (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]

.chloggen/mx-psi_weaklytypedinput.yaml

@@ -0,0 +1,28 @@
+# 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: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds alpha `confmap.strictlyTypedInput` feature gate that enables strict type checks during configuration resolution"
+
+# One or more tracking issues or pull requests related to the change
+issues: [9532]
+
+# (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: |
+  When enabled, the configuration resolution system will:
+  - Stop doing most kinds of implicit type casting when resolving configuration values
+  - Use the original string representation of configuration values if the ${} syntax is used in inline position
+
+# 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/go.mod

@@ -32,6 +32,7 @@ require (
 	github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/hashicorp/go-version v1.7.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/knadh/koanf/maps v0.1.1 // indirect
 	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
@@ -45,6 +46,7 @@ require (
 	github.com/prometheus/client_model v0.6.1 // indirect
 	github.com/prometheus/common v0.54.0 // indirect
 	github.com/prometheus/procfs v0.15.0 // indirect
+	go.opentelemetry.io/collector/featuregate v1.9.0 // indirect
 	go.opentelemetry.io/otel/exporters/prometheus v0.49.0 // indirect
 	go.opentelemetry.io/otel/sdk v1.27.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect

cmd/mdatagen/go.sum

@@ -14,6 +14,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-viper/mapstructure/v2 v2.0.0-alpha.1 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/hashicorp/go-version v1.7.0 // indirect
 	github.com/knadh/koanf/maps v0.1.1 // indirect
 	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
 	github.com/knadh/koanf/v2 v2.1.1 // indirect
@@ -22,6 +23,7 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	go.opentelemetry.io/collector/config/configtelemetry v0.102.1 // indirect
 	go.opentelemetry.io/collector/confmap v0.102.1 // indirect
+	go.opentelemetry.io/collector/featuregate v1.9.0 // indirect
 	go.opentelemetry.io/collector/pdata v1.9.0 // indirect
 	go.opentelemetry.io/otel v1.27.0 // indirect
 	go.opentelemetry.io/otel/metric v1.27.0 // indirect
@@ -48,3 +50,5 @@ replace go.opentelemetry.io/collector/config/configtelemetry => ../configtelemet
 replace go.opentelemetry.io/collector/extension => ../../extension
 
 replace go.opentelemetry.io/collector/extension/auth => ../../extension/auth
+
+replace go.opentelemetry.io/collector/featuregate => ../../featuregate

config/configauth/go.mod

@@ -16,6 +16,7 @@ import (
 	"github.com/knadh/koanf/providers/confmap"
 	"github.com/knadh/koanf/v2"
 
+	"go.opentelemetry.io/collector/confmap/internal"
 	encoder "go.opentelemetry.io/collector/confmap/internal/mapstructure"
 )
 
@@ -156,7 +157,7 @@ func decodeConfig(m *Conf, result any, errorUnused bool, skipTopLevelUnmarshaler
 		ErrorUnused:      errorUnused,
 		Result:           result,
 		TagName:          "mapstructure",
-		WeaklyTypedInput: true,
+		WeaklyTypedInput: !internal.StrictlyTypedInputGate.IsEnabled(),
 		MatchName:        caseSensitiveMatchName,
 		DecodeHook: mapstructure.ComposeDecodeHookFunc(
 			expandNilStructPointersHookFunc(),

config/configauth/go.sum

@@ -11,6 +11,8 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+
+	"go.opentelemetry.io/collector/confmap/internal"
 )
 
 // schemePattern defines the regexp pattern for scheme names.
@@ -111,7 +113,12 @@ func (mr *Resolver) findAndExpandURI(ctx context.Context, input string) (any, bo
 	if uri == input {
 		// If the value is a single URI, then the return value can be anything.
 		// This is the case `foo: ${file:some_extra_config.yml}`.
-		expanded, err := mr.expandURI(ctx, input)
+		ret, err := mr.expandURI(ctx, input)
+		if err != nil {
+			return input, false, err
+		}
+
+		expanded, err := ret.AsRaw()
 		if err != nil {
 			return input, false, err
 		}
@@ -121,16 +128,27 @@ func (mr *Resolver) findAndExpandURI(ctx context.Context, input string) (any, bo
 	if err != nil {
 		return input, false, err
 	}
-	repl, err := toString(expanded)
+
+	var repl string
+	if internal.StrictlyTypedInputGate.IsEnabled() {
+		repl, err = expanded.AsString()
+	} else {
+		repl, err = toString(expanded)
+	}
 	if err != nil {
 		return input, false, fmt.Errorf("expanding %v: %w", uri, err)
 	}
 	return strings.ReplaceAll(input, uri, repl), true, err
 }
 
 // toString attempts to convert input to a string.
-func toString(input any) (string, error) {
+func toString(ret *Retrieved) (string, error) {
 	// This list must be kept in sync with checkRawConfType.
+	input, err := ret.AsRaw()
+	if err != nil {
+		return "", err
+	}
+
 	val := reflect.ValueOf(input)
 	switch val.Kind() {
 	case reflect.String:
@@ -146,7 +164,7 @@ func toString(input any) (string, error) {
 	}
 }
 
-func (mr *Resolver) expandURI(ctx context.Context, input string) (any, error) {
+func (mr *Resolver) expandURI(ctx context.Context, input string) (*Retrieved, error) {
 	// strip ${ and }
 	uri := input[2 : len(input)-1]
 
@@ -167,7 +185,7 @@ func (mr *Resolver) expandURI(ctx context.Context, input string) (any, error) {
 		return nil, err
 	}
 	mr.closers = append(mr.closers, ret.Close)
-	return ret.AsRaw()
+	return ret, nil
 }
 
 type location struct {

confmap/confmap.go

@@ -8,6 +8,7 @@ require (
 	github.com/knadh/koanf/providers/confmap v0.1.0
 	github.com/knadh/koanf/v2 v2.1.1
 	github.com/stretchr/testify v1.9.0
+	go.opentelemetry.io/collector/featuregate v1.9.0
 	go.uber.org/goleak v1.3.0
 	go.uber.org/multierr v1.11.0
 	go.uber.org/zap v1.27.0
@@ -16,15 +17,15 @@ require (
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/kr/pretty v0.3.1 // indirect
+	github.com/hashicorp/go-version v1.7.0 // indirect
 	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/rogpeppe/go-internal v1.10.0 // indirect
-	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 )
 
 retract (
 	v0.76.0 // Depends on retracted pdata v1.0.0-rc10 module, use v0.76.1
 	v0.69.0 // Release failed, use v0.69.1
 )
+
+replace go.opentelemetry.io/collector/featuregate => ../featuregate

confmap/expand.go

@@ -7,11 +7,13 @@ require (
 	go.opentelemetry.io/collector/confmap v0.102.1
 	go.opentelemetry.io/collector/confmap/provider/envprovider v0.102.1
 	go.opentelemetry.io/collector/confmap/provider/fileprovider v0.102.1
+	go.opentelemetry.io/collector/featuregate v1.9.0
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-viper/mapstructure/v2 v2.0.0 // indirect
+	github.com/hashicorp/go-version v1.7.0 // indirect
 	github.com/knadh/koanf/maps v0.1.1 // indirect
 	github.com/knadh/koanf/providers/confmap v0.1.0 // indirect
 	github.com/knadh/koanf/v2 v2.1.1 // indirect
@@ -28,3 +30,5 @@ replace go.opentelemetry.io/collector/confmap => ../../
 replace go.opentelemetry.io/collector/confmap/provider/fileprovider => ../../provider/fileprovider
 
 replace go.opentelemetry.io/collector/confmap/provider/envprovider => ../../provider/envprovider
+
+replace go.opentelemetry.io/collector/featuregate => ../../../featuregate