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kdumpctl: wait a while for network ready if dump target is ssh

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If dump target is ipv6 address, a host should have ipv6 address ready
before starting kdump service. Otherwise, kdump service fails to start due
to the failure "ssh dump_server_ip mkdir -p $SAVE_PATH".
And user can see message like:
 "Could not create root@2620:52:0:10da:46a8:42ff:fe23:3272/var/crash"

I observe a long period (about 30s) on some machine before they got ipv6
address dynamiclly, which is never seen on ipv4 host.

Hence kdump service has a dependency on ipv6 address. But there is no good
way to resolve it. One way is asking user to run the cmd "nmcli connection
modify eth0 ipv6.may-fail false". But this will block systemd until ipv6
address is ready. Despite doing so, kdump can try its best (wait 1 minutes
after it starts up) before failure.

How to implement the wait is arguable. It will involve too many technique
details if explicitly waiting on ipv6 address, instead, just lean on 'ssh'
return value to see the availability of network.

Signed-off-by: Pingfan Liu <piliu@redhat.com>
Acked-by: Kairui Song <kasong@redhat.com>
This commit is contained in:
Pingfan Liu 2019-08-12 16:07:39 +08:00 committed by Kairui Song
parent 15f6d2627f
commit c1a06343df
1 changed files with 31 additions and 4 deletions
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35
kdumpctl
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@ -730,12 +730,39 @@ check_ssh_config()
return 0
}
# ipv6 host address may takes a long time to be ready.
# Instead of checking against ipv6 address, we just check the network reachable
# by the return val of 'ssh'
check_and_wait_network_ready()
{
local start_time=$(date +%s)
local cur
local diff
while true; do
ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
# ssh exits with the exit status of the remote command or with 255 if an error occurred
if [ $? -eq 0 ]; then
return 0
elif [ $? -ne 255 ]; then
return 1
fi
cur=$(date +%s)
diff=$( $cur - $start_time )
# 60s time out
if [ $diff -gt 60 ]; then
break;
fi
sleep 1
done
return 1
}
check_ssh_target()
{
local _ret
ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
_ret=$?
if [ $_ret -ne 0 ]; then
check_and_wait_network_ready
if [ $? -ne 0 ]; then
echo "Could not create $DUMP_TARGET:$SAVE_PATH, you probably need to run \"kdumpctl propagate\"" >&2
return 1
fi