Handle meta-data commands that return multiple values.

cmd/chirpstack-gateway-bridge/cmd/configfile.go

@@ -418,6 +418,15 @@ marshaler="{{ .Integration.Marshaler }}"
   # Max. execution duration.
   max_execution_duration="{{ .MetaData.Dynamic.MaxExecutionDuration }}"
 
+  # Split delimiter.
+  #
+  # When the output of a command returns multiple lines, ChirpStack Gateway Bridge
+  # assumes multiple values are returned. In this case it will split by the given delimiter
+  # to obtain the key / value of each row. The key will be prefixed with the name of the
+  # configured command.
+  split_delimiter="{{ .MetaData.Dynamic.SplitDelimiter }}"
+
+
   # Commands to execute.
   #
   # The value of the stdout will be used as the key value (string).

cmd/chirpstack-gateway-bridge/cmd/root.go

@@ -67,6 +67,7 @@ func init() {
 
 	viper.SetDefault("integration.mqtt.auth.azure_iot_hub.sas_token_expiration", 24*time.Hour)
 
+	viper.SetDefault("meta_data.dynamic.split_delimiter", "=")
 	viper.SetDefault("meta_data.dynamic.execution_interval", time.Minute)
 	viper.SetDefault("meta_data.dynamic.max_execution_duration", time.Second)
 

docs/content/install/config.md

@@ -446,6 +446,15 @@ marshaler="protobuf"
   # Max. execution duration.
   max_execution_duration="1s"
 
+  # Split delimiter.
+  #
+  # When the output of a command returns multiple lines, ChirpStack Gateway Bridge
+  # assumes multiple values are returned. In this case it will split by the given delimiter
+  # to obtain the key / value of each row. The key will be prefixed with the name of the
+  # configured command.
+  split_delimiter="="
+
+
   # Commands to execute.
   #
   # The value of the stdout will be used as the key value (string).

internal/config/config.go

@@ -110,13 +110,14 @@ type Config struct {
 			EndpointEnabled bool   `mapstructure:"endpoint_enabled"`
 			Bind            string `mapstructure:"bind"`
 		} `mapstructure:"prometheus"`
-	}	`mapstructure:"metrics"`
+	} `mapstructure:"metrics"`
 
 	MetaData struct {
 		Static  map[string]string `mapstructure:"static"`
 		Dynamic struct {
 			ExecutionInterval    time.Duration     `mapstructure:"execution_interval"`
 			MaxExecutionDuration time.Duration     `mapstructure:"max_execution_duration"`
+			SplitDelimiter       string            `mapstructure:"split_delimiter"`
 			Commands             map[string]string `mapstructure:"commands"`
 		} `mapstructure:"dynamic"`
 	} `mapstructure:"meta_data"`

internal/metadata/metadata.go

@@ -22,8 +22,9 @@ var (
 	cmnds  map[string]string
 	cached map[string]string
 
-	interval     time.Duration
-	maxExecution time.Duration
+	interval       time.Duration
+	maxExecution   time.Duration
+	splitDelimiter string
 )
 
 // Setup configures the metadata package.
@@ -36,6 +37,7 @@ func Setup(conf config.Config) error {
 
 	interval = conf.MetaData.Dynamic.ExecutionInterval
 	maxExecution = conf.MetaData.Dynamic.MaxExecutionDuration
+	splitDelimiter = conf.MetaData.Dynamic.SplitDelimiter
 
 	go func() {
 		for {
@@ -71,7 +73,23 @@ func runCommands() {
 			continue
 		}
 
-		newKV[k] = out
+		if strings.Contains(out, "\n") {
+			rows := strings.Split(out, "\n")
+			for _, row := range rows {
+				kv := strings.Split(row, splitDelimiter)
+				if len(kv) != 2 {
+					log.WithFields(log.Fields{
+						"row":             row,
+						"split_delimiter": splitDelimiter,
+					}).Warning("metadata: can not split output in key / value")
+				} else {
+					newKV[k+"_"+kv[0]] = kv[1]
+				}
+			}
+
+		} else {
+			newKV[k] = out
+		}
 	}
 
 	mux.Lock()

internal/metadata/metadata_test.go

@@ -116,9 +116,20 @@ func TestMetaData(t *testing.T) {
 				"bar": "test2",
 			},
 		},
+		{
+			Name: "command returns multiple rows",
+			Commands: map[string]string{
+				"bar": `echo -e "foo=bar\nalice=bob"`,
+			},
+			Expected: map[string]string{
+				"bar_foo":   "bar",
+				"bar_alice": "bob",
+			},
+		},
 	}
 
 	maxExecution = time.Second
+	splitDelimiter = "="
 
 	for _, tst := range tests {
 		t.Run(tst.Name, func(t *testing.T) {