1 # Capturing VPP core dumps
2 In order to debug a crash of VPP, it is required to provide a coredump file, which allows backtracing of the VPP issue. The following items are the requirements for capturing a coredump:
4 #### 1. Disable k8s Probes to Prevent k8s from Restarting the POD with a Crashed VPP
5 As described in [BUG_REPORTS.md](BUG_REPORTS.html#collecting-the-logs-in-case-of-crash-loop).
7 #### 2. Modify VPP Startup config file
8 In `/etc/vpp/contiv-vswitch.conf`, add the following lines into the `unix` section:
13 coredump-size unlimited
18 #### 3. Turn on Coredumps in the Vswitch Container
19 After re-deploying Contiv-VPP networking, enter bash shell in the vswitch
20 container (use actual name of the vswitch POD - `contiv-vswitch-7whk7` in this case):
22 kubectl exec -it contiv-vswitch-7whk7 -n kube-system -c contiv-vswitch bash
28 sysctl -w debug.exception-trace=1
29 sysctl -w kernel.core_pattern="/tmp/dumps/%e-%t"
31 echo 2 > /proc/sys/fs/suid_dumpable
35 Now repeat the steps that lead to the VPP crash. You can also force VPP to crash at the point where it is
36 running (e.g., if it is stuck) by using the SIGQUIT signal:
41 #### 5. Locate and Inspect the Core File
42 The core file should appear in `/tmp/dumps` in the container:
49 You can try to backtrace, after installing gdb:
51 apt-get update && apt-get install gdb
52 gdb vpp vpp_main-1524124440
56 #### 6. Copy the Core File Out of the Container
57 Finally, copy the core file out of the container. First, while still inside the container,
58 pack the core file into an archive:
62 tar cvzf vppdump.tar.gz vpp_main-1524124440
65 Now, on the host, determine the docker ID of the container, and then copy the file out of the host:
67 docker ps | grep vswitch_contiv
68 d7aceb2e4876 c43a70ac3d01 "/usr/bin/supervisor…" 25 minutes ago Up 25 minutes k8s_contiv-vswitch_contiv-vswitch-zqzn6_kube-system_9923952f-43a6-11e8-be84-080027de08ea_0
70 docker cp d7aceb2e4876:/tmp/dumps/vppdump.tar.gz .
73 Now you are ready to file a bug in [jira.fd.io](https://jira.fd.io/) and attach the core file.