From 300cf75d84abf7599db5a96c701504189a779913 Mon Sep 17 00:00:00 2001
From: Matthieu Vachon <matt@streamingfast.io>
Date: Thu, 25 Apr 2024 16:44:34 -0400
Subject: [PATCH] The `common-metering-plugin` now expands environment
 variables

---
 cmd/apps/metering.go         | 37 ++++++++++++++++++++++++++++++++++++
 cmd/apps/start.go            |  2 +-
 cmd/apps/substreams_tier1.go |  4 +---
 3 files changed, 39 insertions(+), 4 deletions(-)
 create mode 100644 cmd/apps/metering.go

diff --git a/cmd/apps/metering.go b/cmd/apps/metering.go
new file mode 100644
index 0000000..a333d1b
--- /dev/null
+++ b/cmd/apps/metering.go
@@ -0,0 +1,37 @@
+package apps
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"github.com/streamingfast/dmetering"
+	"go.uber.org/zap"
+)
+
+// GetCommonMeteringPlugin returns the common metering plugin value to use
+// for the application. It reads the `common-metering-plugin` flag
+// from the command and returns the plugin after expanding the
+// environment variables in it meaning 'paymentGateway://test?token=${TOKEN}'.
+func GetCommonMeteringPluginValue() string {
+	plugin := viper.GetString("common-metering-plugin")
+	return os.ExpandEnv(plugin)
+}
+
+// GetCommonMeteringPlugin returns the common metering plugin to use
+// for the application. It reads the `common-metering-plugin` flag
+// from the command and returns the plugin after expanding the
+// environment variables in it meaning 'paymentGateway://test?token=${TOKEN}'.
+func GetCommonMeteringPlugin(cmd *cobra.Command, logger *zap.Logger) (dmetering.EventEmitter, error) {
+	// We keep cmd as argument for future proofing, at which point we are going to break
+	// GetCommonMeteringPluginValue above.
+	_ = cmd
+
+	eventEmitter, err := dmetering.New(GetCommonMeteringPluginValue(), logger)
+	if err != nil {
+		return nil, fmt.Errorf("new metering plugin: %w", err)
+	}
+
+	return eventEmitter, nil
+}
diff --git a/cmd/apps/start.go b/cmd/apps/start.go
index 74e1efc..b191290 100644
--- a/cmd/apps/start.go
+++ b/cmd/apps/start.go
@@ -73,7 +73,7 @@ func start(cmd *cobra.Command, dataDir string, args []string, rootLog *zap.Logge
 		return fmt.Errorf("protocol specific hooks not configured correctly: %w", err)
 	}
 
-	eventEmitter, err := dmetering.New(sflags.MustGetString(cmd, "common-metering-plugin"), rootLog)
+	eventEmitter, err := GetCommonMeteringPlugin(cmd, rootLog)
 	if err != nil {
 		return fmt.Errorf("unable to initialize dmetering: %w", err)
 	}
diff --git a/cmd/apps/substreams_tier1.go b/cmd/apps/substreams_tier1.go
index 9441846..393fd3e 100644
--- a/cmd/apps/substreams_tier1.go
+++ b/cmd/apps/substreams_tier1.go
@@ -119,11 +119,9 @@ func RegisterSubstreamsTier1App[B firecore.Block](chain *firecore.Chain[B], root
 				wasmExtensions = exts
 			}
 
-			meteringConfig := viper.GetString("common-metering-plugin")
-
 			return app.NewTier1(appLogger,
 				&app.Tier1Config{
-					MeteringConfig: meteringConfig,
+					MeteringConfig: GetCommonMeteringPluginValue(),
 
 					MergedBlocksStoreURL: mergedBlocksStoreURL,
 					OneBlocksStoreURL:    oneBlocksStoreURL,