[confmap] Deprecate expandconverter (#10510)

#### Description
This PR deprecates `expandconverter` and removes its use from
`otelcoltest.LoadConfig` and OCB.

This cannot be merged until the `confmap.unifyEnvVarExpansion` [feature
gate is made
stable](#10508).

<!-- Issue number if applicable -->
#### Link to tracking issue
closes
#10161
closes
#7111
closes
#8215

---------

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

.chloggen/deprecate-expandconverter-2.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: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: otelcoltest
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: The `otelcol.LoadConfig` method no longer sets the `expandconverter`.
+
+# One or more tracking issues or pull requests related to the change
+issues: [10510]
+
+# (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/deprecate-expandconverter-3.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: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: ocb
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Collectors built with OCB will no longer include the `expandconverter`
+
+# One or more tracking issues or pull requests related to the change
+issues: [10510]
+
+# (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/deprecate-expandconverter.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: deprecation
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: expandconverter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Deprecate `expandconverter`.
+
+# One or more tracking issues or pull requests related to the change
+issues: [10510]
+
+# (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]

cmd/builder/README.md

@@ -24,8 +24,6 @@ processors:
 providers:
   - gomod: go.opentelemetry.io/collector/confmap/provider/fileprovider v0.99.0
 
-converters:
-  - gomod: go.opentelemetry.io/collector/confmap/converter/expandconverter v0.99.0
 EOF
 $ builder --config=otelcol-builder.yaml
 $ cat > /tmp/otelcol.yaml <<EOF

cmd/builder/internal/builder/main_test.go

@@ -54,7 +54,6 @@ var (
 		"/config/configtls",
 		"/config/internal",
 		"/confmap",
-		"/confmap/converter/expandconverter",
 		"/confmap/provider/envprovider",
 		"/confmap/provider/fileprovider",
 		"/confmap/provider/httpprovider",

cmd/builder/internal/builder/templates/go.mod.tmpl

@@ -6,7 +6,6 @@ go 1.21
 
 require (
 	{{if .Distribution.SupportsConfmapFactories -}}
-	go.opentelemetry.io/collector/confmap/converter/expandconverter v{{.Distribution.OtelColVersion}}
 	{{- range .Providers}}
 	{{if .GoMod}}{{.GoMod}}{{end}}
 	{{- end}}

cmd/builder/internal/builder/templates/main.go.tmpl

@@ -9,7 +9,6 @@ import (
 	"go.opentelemetry.io/collector/component"
 	{{- if .Distribution.SupportsConfmapFactories}}
 	"go.opentelemetry.io/collector/confmap"
-	"go.opentelemetry.io/collector/confmap/converter/expandconverter"
 	{{- range .Providers}}
 	{{.Name}} "{{.Import}}"
 	{{- end}}
@@ -38,9 +37,6 @@ func main() {
 				{{- if .ConfResolver.DefaultURIScheme }}
 				DefaultScheme: "{{ .ConfResolver.DefaultURIScheme }}",
 				{{- end }}
-				ConverterFactories: []confmap.ConverterFactory{
-					expandconverter.NewFactory(),
-				},
 			},
 		},
 		{{- end}}

cmd/builder/test/core.builder.yaml

@@ -33,7 +33,6 @@ replaces:
   - go.opentelemetry.io/collector/config/configtls => ${WORKSPACE_DIR}/config/configtls
   - go.opentelemetry.io/collector/config/internal => ${WORKSPACE_DIR}/config/internal
   - go.opentelemetry.io/collector/confmap => ${WORKSPACE_DIR}/confmap
-  - go.opentelemetry.io/collector/confmap/converter/expandconverter => ${WORKSPACE_DIR}/confmap/converter/expandconverter
   - go.opentelemetry.io/collector/confmap/provider/envprovider => ${WORKSPACE_DIR}/confmap/provider/envprovider
   - go.opentelemetry.io/collector/confmap/provider/fileprovider => ${WORKSPACE_DIR}/confmap/provider/fileprovider
   - go.opentelemetry.io/collector/confmap/provider/httpprovider => ${WORKSPACE_DIR}/confmap/provider/httpprovider

cmd/otelcorecol/builder-config.yaml

@@ -57,7 +57,6 @@ replaces:
   - go.opentelemetry.io/collector/config/configtls => ../../config/configtls
   - go.opentelemetry.io/collector/config/internal => ../../config/internal
   - go.opentelemetry.io/collector/confmap => ../../confmap
-  - go.opentelemetry.io/collector/confmap/converter/expandconverter => ../../confmap/converter/expandconverter
   - go.opentelemetry.io/collector/confmap/provider/envprovider => ../../confmap/provider/envprovider
   - go.opentelemetry.io/collector/confmap/provider/fileprovider => ../../confmap/provider/fileprovider
   - go.opentelemetry.io/collector/confmap/provider/httpprovider => ../../confmap/provider/httpprovider

cmd/otelcorecol/go.mod

@@ -9,7 +9,6 @@ toolchain go1.21.12
 require (
 	go.opentelemetry.io/collector/component v0.106.1
 	go.opentelemetry.io/collector/confmap v0.106.1
-	go.opentelemetry.io/collector/confmap/converter/expandconverter v0.106.1
 	go.opentelemetry.io/collector/confmap/provider/envprovider v0.106.1
 	go.opentelemetry.io/collector/confmap/provider/fileprovider v0.106.1
 	go.opentelemetry.io/collector/confmap/provider/httpprovider v0.106.1
@@ -170,8 +169,6 @@ replace go.opentelemetry.io/collector/config/internal => ../../config/internal
 
 replace go.opentelemetry.io/collector/confmap => ../../confmap
 
-replace go.opentelemetry.io/collector/confmap/converter/expandconverter => ../../confmap/converter/expandconverter
-
 replace go.opentelemetry.io/collector/confmap/provider/envprovider => ../../confmap/provider/envprovider
 
 replace go.opentelemetry.io/collector/confmap/provider/fileprovider => ../../confmap/provider/fileprovider

confmap/converter/expandconverter/expand.go

@@ -7,13 +7,11 @@ import (
 	"context"
 	"fmt"
 	"os"
-	"regexp"
 
 	"go.uber.org/zap"
 
 	"go.opentelemetry.io/collector/confmap"
 	"go.opentelemetry.io/collector/confmap/internal/envvar"
-	"go.opentelemetry.io/collector/internal/globalgates"
 )
 
 type converter struct {
@@ -25,6 +23,9 @@ type converter struct {
 
 // NewFactory returns a factory for a  confmap.Converter,
 // which expands all environment variables for a given confmap.Conf.
+//
+// Deprecated: [v0.107.0] BASH-style env var expansion is deprecated. Use the `envprovider` instead to expand `${FOO}` and `${env:FOO}`.
+// Using the expandconverter with `confmap.Resolver` will cause double escaping, so `$$$$` -> `$` instead of `$$`.
 func NewFactory() confmap.ConverterFactory {
 	return confmap.NewConverterFactory(newConverter)
 }
@@ -36,6 +37,8 @@ func newConverter(set confmap.ConverterSettings) confmap.Converter {
 	}
 }
 
+// Deprecated: [v0.107.0] BASH-style env var expansion is deprecated. Use the `envprovider` instead to expand `${FOO}` and `${env:FOO}`.
+// Using the expandconverter with `confmap.Resolver` will cause double escaping, so `$$$$` -> `$` instead of `$$`.
 func (c converter) Convert(_ context.Context, conf *confmap.Conf) error {
 	var err error
 	out := make(map[string]any)
@@ -90,19 +93,6 @@ func (c converter) expandEnv(s string) (string, error) {
 			return "$"
 		}
 
-		// Matches on $VAR style environment variables
-		// in order to make sure we don't log a warning for ${VAR}
-		var regex = regexp.MustCompile(fmt.Sprintf(`\$%s`, regexp.QuoteMeta(str)))
-		if _, exists := c.loggedDeprecations[str]; !exists && regex.MatchString(s) {
-			if globalgates.UseUnifiedEnvVarExpansionRules.IsEnabled() {
-				err = fmt.Errorf("variable substitution using $VAR has been deprecated in favor of ${VAR} and ${env:VAR} - please update $%s or temporarily disable the confmap.unifyEnvVarExpansion feature gate", str)
-				return ""
-			}
-			msg := fmt.Sprintf("Variable substitution using $VAR will be deprecated in favor of ${VAR} and ${env:VAR}, please update $%s", str)
-			c.logger.Warn(msg, zap.String("variable", str))
-			c.loggedDeprecations[str] = struct{}{}
-		}
-
 		// For $ENV style environment variables os.Expand returns once it hits a character that isn't an underscore or
 		// an alphanumeric character - so we cannot detect those malformed environment variables.
 		// For ${ENV} style variables we can detect those kinds of env var names!