docs: add contiv vpp

Change-Id: I92227fc4968fc6a478beb7f38707b91e9f0635ec
Signed-off-by: Scott Keeler <skeeler@cisco.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/docs/usecases/contiv/CORE_FILES.md b/docs/usecases/contiv/CORE_FILES.md
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+# Capturing VPP core dumps
+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:
+
+#### 1. Disable k8s Probes to Prevent k8s from Restarting the POD with a Crashed VPP
+As described in [BUG_REPORTS.md](BUG_REPORTS.html#collecting-the-logs-in-case-of-crash-loop).
+
+#### 2. Modify VPP Startup config file
+In `/etc/vpp/contiv-vswitch.conf`, add the following lines into the `unix` section:
+
+```
+unix {
+    ...
+    coredump-size unlimited
+    full-coredump
+}
+```
+
+#### 3. Turn on Coredumps in the Vswitch Container
+After re-deploying Contiv-VPP networking, enter bash shell in the vswitch 
+container (use actual name of the vswitch POD - `contiv-vswitch-7whk7` in this case):
+```
+kubectl exec -it contiv-vswitch-7whk7 -n kube-system -c contiv-vswitch bash
+```
+
+Enable coredumps:
+```
+mkdir -p /tmp/dumps
+sysctl -w debug.exception-trace=1 
+sysctl -w kernel.core_pattern="/tmp/dumps/%e-%t"
+ulimit -c unlimited
+echo 2 > /proc/sys/fs/suid_dumpable
+```
+
+#### 4. Let VPP Crash
+Now repeat the steps that lead to the VPP crash. You can also force VPP to crash at the point where it is 
+running (e.g., if it is stuck) by using the SIGQUIT signal:
+```
+kill -3 `pidof vpp`
+```
+
+#### 5. Locate and Inspect the Core File
+The core file should appear in `/tmp/dumps` in the container:
+```
+cd /tmp/dumps
+ls
+vpp_main-1524124440
+```
+
+You can try to backtrace, after installing gdb:
+```
+apt-get update && apt-get install gdb
+gdb vpp vpp_main-1524124440
+(gdb) bt
+```
+
+#### 6. Copy the Core File Out of the Container
+Finally, copy the core file out of the container. First, while still inside the container,
+pack the core file into an archive:
+
+```
+cd /tmp/dumps
+tar cvzf vppdump.tar.gz vpp_main-1524124440
+```
+
+Now, on the host, determine the docker ID of the container, and then copy the file out of the host:
+```
+docker ps | grep vswitch_contiv
+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
+
+docker cp d7aceb2e4876:/tmp/dumps/vppdump.tar.gz .
+```
+
+Now you are ready to file a bug in [jira.fd.io](https://jira.fd.io/) and attach the core file.
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