inlet/metadata: prefer ifAlias over ifDescr for interface description

ifDescr is more likely to contain the interface name for compatibility
with ancien stuff (part of the original ifTable). The heuristics about
it being different than ifName is not 100% correct as some IOS XE device
may use the short name for ifDescr and the long name for ifName.

ifAlias contains the description for IOS XR and JunOS.

console/data/docs/99-changelog.md

@@ -13,6 +13,7 @@ identified with a specific icon:
 
 ## Unreleased
 
+- 💥 *inlet*: in SNMP metadata provider, prefer ifAlias over ifDescr for interface description
 - 🌱 *build*: minimal Go version to build is now 1.23
 - 🌱 *orchestrator*: ability to override ClickHouse or Kafka configuration in some components
 

inlet/metadata/provider/snmp/poller.go

@@ -211,10 +211,10 @@ func (p *Provider) Poll(ctx context.Context, exporter, agent netip.Addr, port ui
 				// If we have ifName, use ifDescr if it is different and ifAlias
 				// is not. Otherwise, keep description empty.
 				name = ifNameVal
-				if okDescr && ifDescrVal != ifNameVal {
-					description = ifDescrVal
-				} else if okAlias {
+				if okAlias && ifAliasVal != ifNameVal {
 					description = ifAliasVal
+				} else if okDescr && ifDescrVal != ifNameVal {
+					description = ifDescrVal
 				}
 			} else {
 				// Don't handle the other case yet. It would be unexpected to

inlet/metadata/provider/snmp/poller_test.go

@@ -241,7 +241,7 @@ func TestPoller(t *testing.T) {
 								OID:  "1.3.6.1.2.1.31.1.1.1.18.645",
 								Type: gosnmp.OctetString,
 								OnGet: func() (interface{}, error) {
-									return "GigabitEthernet-something", nil
+									return "Gi0/0/0/5", nil
 								},
 							},
 						},