feat(collector): support inline Base64 config via OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT

collector/README.md

@@ -176,14 +176,40 @@ from an S3 object using a CloudFormation template:
 
 Loading configuration from S3 will require that the IAM role attached to your function includes read access to the relevant bucket.
 
+### Inline configuration via Base64
+
+You can supply the collector configuration inline as a Base64-encoded string using `OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT`. This is useful when you want to avoid deploying a config file or referencing an external URI:
+
+```
+aws lambda update-function-configuration --function-name Function \
+  --environment Variables={OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT=$(base64 < collector.yaml)}
+```
+
+Or in a CloudFormation template:
+
+```yaml
+  Function:
+    Type: AWS::Serverless::Function
+    Properties:
+      ...
+      Environment:
+        Variables:
+          OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT: <output of `base64 < collector.yaml`>
+```
+
+Use the standard Base64 alphabet (as produced by `base64` on Linux/macOS or `openssl base64`). URL-safe Base64 is not supported.
+
+`OPENTELEMETRY_COLLECTOR_CONFIG_URI` takes precedence if both variables are set.
+
 ## Environment Variables
 
 The following environment variables can be used to configure the OpenTelemetry Collector Lambda extension:
 
-| Variable Name                        | Value                                                                          | Description                                                                                                                                                                                                                                                 |
-| ------------------------------------ | ------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `OPENTELEMETRY_COLLECTOR_CONFIG_URI` | URI (e.g., `/var/task/collector.yaml`, `http://...`, `s3://...`)               | Specifies the location of the OpenTelemetry Collector configuration file. This can be a path within the function's deployment package, an HTTP URI, or an S3 URI. If loading from S3, the function's IAM role needs read access to the specified S3 object. |
-| `OPENTELEMETRY_EXTENSION_LOG_LEVEL`  | `debug`, `info`, `warn`, `error`, `dpanic`, `panic`, `fatal` (Default: `info`) | Controls the logging level of the OpenTelemetry Lambda extension itself.                                                                                                                                                                                    |
+| Variable Name                           | Value                                                                          | Description                                                                                                                                                                                                                                                    |
+| --------------------------------------- | ------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `OPENTELEMETRY_COLLECTOR_CONFIG_URI`    | URI (e.g., `/var/task/collector.yaml`, `http://...`, `s3://...`)               | Specifies the location of the OpenTelemetry Collector configuration file. This can be a path within the function's deployment package, an HTTP URI, or an S3 URI. If loading from S3, the function's IAM role needs read access to the specified S3 object.    |
+| `OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT`| Base64-encoded YAML                                                            | Supplies the collector configuration inline. The value must be standard Base64-encoded YAML. Ignored if `OPENTELEMETRY_COLLECTOR_CONFIG_URI` is also set (a warning is logged). If decoding fails, an error is logged and the extension falls back to the URI or default path. |
+| `OPENTELEMETRY_EXTENSION_LOG_LEVEL`     | `debug`, `info`, `warn`, `error`, `dpanic`, `panic`, `fatal` (Default: `info`) | Controls the logging level of the OpenTelemetry Lambda extension itself.                                                                                                                                                                                       |
 
 ## Auto-Configuration
 

collector/internal/collector/collector.go

@@ -16,8 +16,10 @@ package collector
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/confmap/provider/s3provider"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/confmap/provider/secretsmanagerprovider"
@@ -49,23 +51,42 @@ type Collector struct {
 	coreFunc  func(zapcore.LevelEnabler) zapcore.Core
 }
 
+const (
+	envCollectorConfigURI     = "OPENTELEMETRY_COLLECTOR_CONFIG_URI"
+	envCollectorConfigContent = "OPENTELEMETRY_COLLECTOR_CONFIG_CONTENT"
+	envCollectorConfigFile    = "OPENTELEMETRY_COLLECTOR_CONFIG_FILE" // deprecated
+)
+
 func getConfig(logger *zap.Logger) string {
-	val, ex := os.LookupEnv("OPENTELEMETRY_COLLECTOR_CONFIG_URI")
-	if ex {
+	if val, ex := os.LookupEnv(envCollectorConfigURI); ex {
+		if _, also := os.LookupEnv(envCollectorConfigContent); also {
+			logger.Warn("Both " + envCollectorConfigURI + " and " + envCollectorConfigContent + " are set; using " + envCollectorConfigURI)
+		}
 		logger.Info("Using config URI from environment variable", zap.String("uri", val))
 		return val
 	}
 
+	if raw, ex := os.LookupEnv(envCollectorConfigContent); ex {
+		if trimmed := strings.TrimSpace(raw); trimmed != "" {
+			decoded, err := base64.StdEncoding.DecodeString(trimmed)
+			if err != nil {
+				logger.Error("Failed to decode "+envCollectorConfigContent+" as Base64; ignoring", zap.Error(err))
+			} else {
+				logger.Info("Using inline config from " + envCollectorConfigContent)
+				return "yaml:" + string(decoded)
+			}
+		}
+	}
+
 	// The name of the environment variable was changed
 	// This is the old name, kept for backwards compatibility
-	oldVal, oldEx := os.LookupEnv("OPENTELEMETRY_COLLECTOR_CONFIG_FILE")
-	if oldEx {
+	if oldVal, oldEx := os.LookupEnv(envCollectorConfigFile); oldEx {
 		logger.Info("Using config URI from deprecated environment variable", zap.String("uri", oldVal))
-		logger.Warn("The OPENTELEMETRY_COLLECTOR_CONFIG_FILE environment variable is deprecated. Please use OPENTELEMETRY_COLLECTOR_CONFIG_URI instead.")
+		logger.Warn("The " + envCollectorConfigFile + " environment variable is deprecated. Please use " + envCollectorConfigURI + " instead.")
 		return oldVal
 	}
 
-	// If neither environment variable is set, use the default
+	// If no environment variable is set, use the default
 	defaultVal := "/opt/collector-config/config.yaml"
 	logger.Info("Using default config URI", zap.String("uri", defaultVal))
 	return defaultVal

collector/internal/collector/collector_test.go

@@ -16,6 +16,7 @@ package collector
 
 import (
 	"context"
+	"encoding/base64"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -100,6 +101,69 @@ func TestCollectorLogLevelDoesNotSuppressExtensionLogs(t *testing.T) {
 		"extension logs should be controlled by the extension logger, not collector config")
 }
 
+func TestCollectorConfigContentStartsCollector(t *testing.T) {
+	yamlContent := `
+receivers:
+  nop:
+exporters:
+  nop:
+service:
+  telemetry:
+    logs:
+      level: info
+  pipelines:
+    traces:
+      receivers: [nop]
+      exporters: [nop]
+`
+	t.Setenv(envCollectorConfigContent, base64.StdEncoding.EncodeToString([]byte(yamlContent)))
+
+	core, logs := observer.New(zapcore.InfoLevel)
+	col := NewCollector(zap.New(core), testFactories(t), "test")
+
+	ctx := context.Background()
+	err := col.Start(ctx)
+	require.NoError(t, err)
+
+	err = col.Stop()
+	require.NoError(t, err)
+
+	assert.NotEmpty(t, logs.FilterMessage("Using inline config from "+envCollectorConfigContent).All())
+}
+
+func TestCollectorConfigURITakesPrecedenceOverContent(t *testing.T) {
+	t.Setenv(envCollectorConfigURI, "file:testdata/config-info-level.yaml")
+	t.Setenv(envCollectorConfigContent, base64.StdEncoding.EncodeToString([]byte("irrelevant: true")))
+
+	core, logs := observer.New(zapcore.WarnLevel)
+	col := NewCollector(zap.New(core), testFactories(t), "test")
+
+	ctx := context.Background()
+	err := col.Start(ctx)
+	require.NoError(t, err)
+
+	err = col.Stop()
+	require.NoError(t, err)
+
+	warnLogs := logs.FilterMessageSnippet(envCollectorConfigContent + " are set").All()
+	assert.NotEmpty(t, warnLogs, "expected a warning about both env vars being set")
+}
+
+func TestCollectorConfigContentInvalidBase64FallsBack(t *testing.T) {
+	t.Setenv(envCollectorConfigContent, "not-valid-base64!@#$")
+
+	core, logs := observer.New(zapcore.ErrorLevel)
+	col := NewCollector(zap.New(core), testFactories(t), "test")
+
+	ctx := context.Background()
+	// Collector will fall back to the default path which won't exist — expect start error
+	err := col.Start(ctx)
+	assert.Error(t, err, "expected collector to fail when falling back to missing default config")
+
+	errorLogs := logs.FilterMessageSnippet("Failed to decode").All()
+	assert.NotEmpty(t, errorLogs, "expected an error log about invalid Base64")
+}
+
 func testFactories(t *testing.T) otelcol.Factories {
 	receivers, err := otelcol.MakeFactoryMap(receivertest.NewNopFactory())
 	require.NoError(t, err)