inlet/snmp: fix parsing of inlet.snmp.communities as a string

Fix #116

console/data/docs/99-changelog.md

@@ -14,6 +14,7 @@ identified with a specific icon:
 ## Unreleased
 
 - 🩹 *orchestrator*: validate configuration of other services on start
+- 🩹 *inlet*: correctly parse `inlet.snmp.communities` when it is just a string
 - 🌱 *inlet*: add `inlet.snmp.ports` to configure SNMP exporter ports
 
 ## 1.5.7 - 2022-08-23

inlet/snmp/config.go

@@ -105,13 +105,17 @@ func ConfigurationUnmarshallerHook() mapstructure.DecodeHookFunc {
 			if mapKey == nil {
 				// Use the fact we can set the default value directly.
 				from.SetMapIndex(reflect.ValueOf("communities"), from.MapIndex(*defaultKey))
+			} else if communities.Kind() == reflect.String {
+				return nil, errors.New("do not provide default-community when using communities")
 			} else {
 				communities.SetMapIndex(reflect.ValueOf("::/0"), from.MapIndex(*defaultKey))
 			}
 		} else {
-			// default-community should contain ::/0
+			// communities should contain ::/0
 			if mapKey == nil {
 				from.SetMapIndex(reflect.ValueOf("communities"), reflect.ValueOf("public"))
+			} else if communities.Kind() == reflect.String {
+				// Do nothing
 			} else if !communities.MapIndex(reflect.ValueOf("::/0")).IsValid() {
 				communities.SetMapIndex(reflect.ValueOf("::/0"), reflect.ValueOf("public"))
 			}

inlet/snmp/config_test.go

@@ -101,6 +101,29 @@ func TestConfigurationUnmarshallerHook(t *testing.T) {
 					"::ffff:203.0.113.128/121": "private",
 				}),
 			},
+		}, {
+			Description: "communities as a string",
+			Initial:     func() interface{} { return Configuration{} },
+			Configuration: func() interface{} {
+				return gin.H{
+					"communities": "private",
+				}
+			},
+			Expected: Configuration{
+				Communities: helpers.MustNewSubnetMap(map[string]string{
+					"::/0": "private",
+				}),
+			},
+		}, {
+			Description: "communities as a string, default-community",
+			Initial:     func() interface{} { return Configuration{} },
+			Configuration: func() interface{} {
+				return gin.H{
+					"default-community": "nothing",
+					"communities":       "private",
+				}
+			},
+			Error: true,
 		}, {
 			Description: "communities, default-community empty",
 			Initial:     func() interface{} { return Configuration{} },