From 09dadd948be39fd5008ce1e7d917cd1128d2dbf4 Mon Sep 17 00:00:00 2001
From: James Shaw <james.omnistat@gmail.com>
Date: Wed, 14 Feb 2024 21:48:42 +0000
Subject: [PATCH] Added ability to specify multiple config files

---
 README.md          |  4 +++-
 config/load.go     | 45 ++++++++++++++++++++++++++++-----------------
 modbus_exporter.go |  4 ++--
 3 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 7517ea1..05f087f 100644
--- a/README.md
+++ b/README.md
@@ -62,7 +62,7 @@ usage: modbus_exporter [<flags>]
 Flags:
   -h, --[no-]help                Show context-sensitive help (also try
                                  --help-long and --help-man).
-      --config.file="modbus.yml"  
+      --config.file=modbus.yml ...  
                                  Sets the configuration file.
       --[no-]web.systemd-socket  Use systemd socket activation listeners instead
                                  of port listeners (Linux only).
@@ -89,6 +89,8 @@ Visit http://localhost:9602/metrics to get the metrics of the exporter itself.
 Check out [`modbus.yml`](/modbus.yml) for more details on the configuration file
 format.
 
+The `--config.file` parameter can be used multiple times to load more than one file.
+It also supports [glob filename matching](https://pkg.go.dev/path/filepath#Glob), e.g. `modbus_*.yml`.
 
 ## TODO
 
diff --git a/config/load.go b/config/load.go
index e18da14..ea848c1 100755
--- a/config/load.go
+++ b/config/load.go
@@ -15,27 +15,38 @@ package config
 
 import (
 	"os"
+	"path/filepath"
 
 	yaml "gopkg.in/yaml.v2"
 )
 
-// LoadConfig unmarshals the targets configuration file.
-func LoadConfig(pathToTargets string) (Config, error) {
-	ls := Config{}
-	yamlFile, err := os.ReadFile(pathToTargets)
-	if err != nil {
-		return Config{}, err
-
-	}
-
-	err = yaml.Unmarshal(yamlFile, &ls)
-	if err != nil {
-		return Config{}, err
-	}
-
-	if err := ls.validate(); err != nil {
-		return Config{}, err
+// LoadConfig unmarshals the targets configuration file(s).
+func LoadConfig(pathToTargets []string) (Config, error) {
+	fullConfig := Config{}
+	for _, p := range pathToTargets {
+		files, err := filepath.Glob(p)
+		if err != nil {
+			return Config{}, err
+		}
+		for _, f := range files {
+			ls := Config{}
+			yamlFile, err := os.ReadFile(f)
+			if err != nil {
+				return Config{}, err
+			}
+
+			err = yaml.Unmarshal(yamlFile, &ls)
+			if err != nil {
+				return Config{}, err
+			}
+
+			if err := ls.validate(); err != nil {
+				return Config{}, err
+			}
+
+			fullConfig.Modules = append(fullConfig.Modules, ls.Modules...)
+		}
 	}
 
-	return ls, nil
+	return fullConfig, nil
 }
diff --git a/modbus_exporter.go b/modbus_exporter.go
index 7a35f6d..e24d733 100644
--- a/modbus_exporter.go
+++ b/modbus_exporter.go
@@ -41,7 +41,7 @@ func main() {
 		configFile = kingpin.Flag(
 			"config.file",
 			"Sets the configuration file.",
-		).Default("modbus.yml").String()
+		).Default("modbus.yml").Strings()
 		toolkitFlags = webflag.AddFlags(kingpin.CommandLine, ":9602")
 	)
 
@@ -59,7 +59,7 @@ func main() {
 	telemetryRegistry.MustRegister(collectors.NewGoCollector())
 	telemetryRegistry.MustRegister(collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}))
 
-	level.Info(logger).Log("msg", "Loading configuration file", "config_file", *configFile)
+	level.Info(logger).Log("msg", "Loading configuration file(s)", "config_file", strings.Join(*configFile, ", "))
 	config, err := config.LoadConfig(*configFile)
 	if err != nil {
 		level.Error(logger).Log("msg", "Error loading config", "err", err)