Segfault with managed dynamic configs

[agis]

After upgrading the relay to ab7647a (the latest master, as of now), it started throwing segfaults:

Aug 13 14:00:32 foo relay[557]: time="2018-08-13T14:00:32+03:00" level=info msg="Using config file '/etc/relay.conf'."
Aug 13 14:00:32 foo relay[557]: time="2018-08-13T14:00:32+03:00" level=info msg="Relay 8b3dcfd8-41ec-44f7-a5ac-a3c1652fe9c1 is initializing."
Aug 13 14:00:32 foo relay[557]: time="2018-08-13T14:00:32+03:00" level=info msg="Started 16 request workers."
Aug 13 14:00:33 foo relay[557]: time="2018-08-13T14:00:33+03:00" level=info msg="Managed bundle dynamic configs enabled."
Aug 13 14:00:33 foo relay[557]: time="2018-08-13T14:00:33+03:00" level=info msg="Refreshing bundle dynamic configs every 5s."
Aug 13 14:00:35 foo relay[557]: panic: runtime error: invalid memory address or nil pointer dereference
Aug 13 14:00:35 foo relay[557]: [signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x7404e8]
Aug 13 14:00:35 foo relay[557]: goroutine 1 [running]:
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay.(*DynamicConfigUpdater).refreshConfigs(0xc4203e0000)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/dynamic_config.go:104 +0xd8
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay.(*DynamicConfigUpdater).Run(0xc4203e0000, 0x24, 0xc420016009)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/dynamic_config.go:55 +0x19c
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay.(*cogRelay).handleBusEvents(0xc420010540, 0x87a600, 0xc420296d80, 0x0)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/relay.go:133 +0x5bc
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay.(*cogRelay).(github.com/operable/go-relay/relay.handleBusEvents)-fm(0x87a600, 0xc420296d80, 0x0)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/relay.go:79 +0x48
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay/bus.(*MQTTConnection).Connect(0xc420296d80, 0xc42025b920, 0x2e, 0xc420018010, 0x10, 0xc42001603f, 0x15, 0x75b, 0x0, 0x0, ...)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/bus/mqtt.go:51 +0x3b0
Aug 13 14:00:35 foo relay[557]: github.com/operable/go-relay/relay.(*cogRelay).Start(0xc420010540, 0x878240, 0xc420010540)
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/relay/relay.go:91 +0x4f9
Aug 13 14:00:35 foo relay[557]: main.main()
Aug 13 14:00:35 foo relay[557]: /Users/agis/dev/go/src/github.com/operable/go-relay/main.go:182 +0x214

After bisecting, it's apparent that 6a9d3ec caused this.

We do have the managed dynamic configuration mode enabled.

[wasilak]

Same happens to me. For the time being downgrading to operable/relay:1.0.1 did the trick.