CI: different workfows - connectivity test - failing with panic "runtime error: index out of range [3] with length 0" #43901
Description
There are more CI failures with the same reasons, personally I checked and verified logs from:
https://github.com/cilium/cilium/actions/runs/21202871770
https://github.com/cilium/cilium/actions/runs/21201773204
https://github.com/cilium/cilium/actions/runs/21205748555
The Cilium agent panics with "index out of range" in pkg/datapath/linux/config/config.go during startup or configuration regeneration.
example of the error:
message: "=health reporter-id=agent.datapath.orchestrator.job-reinitialize\npanic:
runtime error: index out of range [3] with length 0\n\ngoroutine 416 [running]:\ngithub.com/cilium/cilium/pkg/byteorder.NetIPv4ToHost32({0x0?,
0xc000e12a50?, 0x4b2389c?})\n\t/go/src/github.com/cilium/cilium/pkg/byteorder/byteorder.go:15
+0x65\ngithub.com/cilium/cilium/pkg/datapath/linux/config.(*HeaderfileWriter).WriteNodeConfig(0xc001ed8d80,
{0x7f1bb24621c8, 0xc002ef6c80}, 0xc000fe5208)\n\t/go/src/github.com/cilium/cilium/pkg/datapath/linux/config/config.go:143
+0x973\ngithub.com/cilium/cilium/pkg/datapath/loader.hashDatapath({0x51db458,
0xc001ed8d80}, 0xc000fe5208)\n\t/go/src/github.com/cilium/cilium/pkg/datapath/loader/hash.go:20
+0xa9\ngithub.com/cilium/cilium/pkg/datapath/loader.(*objectCache).UpdateDatapathHash(0xc000bc2f50,
0xc0024a85f0?)\n\t/go/src/github.com/cilium/cilium/pkg/datapath/loader/cache.go:65
+0x4d\ngithub.com/cilium/cilium/pkg/datapath/loader.(*loader).Reinitialize(0xc001fc9b80,
{0x51d3f58, 0xc000b14870}, 0xc000fe5208, {{0x4aa10bf, 0x4}, {0x0, 0x0},
0x0, 0x0, ...}, ...)\n\t/go/src/github.com/cilium/cilium/pkg/datapath/loader/base.go:356
+0x3be\ngithub.com/cilium/cilium/pkg/datapath/orchestrator.(*orchestrator).reinitialize(0xc002008b08,
{0x51d3f58?, 0xc000b14870?}, {{0x0?, 0x0?}, 0x0?}, 0xc000fe5208)\n\t/go/src/github.com/cilium/cilium/pkg/datapath/orchestrator/orchestrator.go:284
+0x128\ngithub.com/cilium/cilium/pkg/datapath/orchestrator.(*orchestrator).reconciler(0xc002008b08,
{0x51d3f58, 0xc000b14870}, {0x51e9c80, 0xc0022f24e0})\n\t/go/src/github.com/cilium/cilium/pkg/datapath/orchestrator/orchestrator.go:229
+0x805\ngithub.com/cilium/hive/job.(*jobOneShot).start(0xc002060000, {0x51d3f58,
0xc000b14870}, 0xc002c4dfd0?, {0x51e9c80, 0xc001ed9f20}, {{{0xc001f"
reason: Error
startedAt: "2026-01-21T09:00:16Z"
Reason: When EnableIPv4 is set to true, WriteNodeConfig unconditionally attempts to convert cfg.CiliumInternalIPv4 to a 32-bit host integer. If the internal IP (router IP) has not yet been initialized (e.g. waiting for IPAM or K8s sync), accessing the nil byte slice causes the panic in byteorder.
if option.Config.EnableIPv4 {
ipv4GW := cfg.CiliumInternalIPv4
cDefinesMap["IPV4_GATEWAY"] = fmt.Sprintf("%#x", byteorder.NetIPv4ToHost32(ipv4GW))