Re: [PATCH v2] kdumpctl: time out after 180 seconds when connecting to ssh host

[Vivek Goyal]

On Tue, Jun 03, 2014 at 03:55:50PM +0800, WANG Chao wrote:
> When starting kdump service with dump target being ssh host, after
> network-online.target, we connect to ssh host and touch the dump
> directory to make sure the host is ready to be dumped to.
>
> Chances are after network-online.target, the particular network resource
> we interest in isn't ready for connecting to the specified ssh host.
> And at that time, we connect to ssh host and fail.
>
> What we should do is to wait for the specific network resource, not
> totally depending on network-online.target. But it's relatively
> complicated to implement. A simple and direct solution would be try as
> many time as it needs to connect to the configured ssh host. However to
> avoid a infinitely loop, we time out and fail. I set this time out value
> to be 180 seconds, and general speaking, 180 seconds would be enough for
> almost any kind of network to be up and ready.
>
> Vivek:
> sleep 2 seconds after each retry.
> output a brief message for each retry/failure.
> Signed-off-by: WANG Chao
>
> kdumpctl | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/kdumpctl b/kdumpctl
> index 9cae0c4..5e4b1b0 100755
> --- a/kdumpctl
> +++ b/kdumpctl
> @@ -381,9 +381,23 @@ function check_ssh_config()
>  function check_ssh_target()
>  {
>    local _ret
> ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
> _ret=$?
> local _start _delta
> # Timeout out after 180 seconds, hopefully it's enough.
> _start=$(date +%s)
> while : ; do
> ssh -q -i $SSH_KEY_LOCATION -o BatchMode=yes $DUMP_TARGET mkdir -p $SAVE_PATH
> _ret=$?
> _delta=$(($(date +%s) - $_start))
> if [[ $_ret -eq 0 || $_delta -gt 180 ]]; then
> 	break

Hey Chao,

I wanted this "180" second interval being declared separtely instead of
using it directly here.

SSH_POLLING_TIMEOUT	180

So either declare it in same file or in kdump-lib.sh as you see fit.
> fi
> echo "ssh to $DUMP_TARGET failed. Will retry after 2 seconds"
> sleep 2
> done
> if [ $_ret -ne 0 ]; then
> echo "ssh failed after multiple tries"
> echo "Could not create $DUMP_TARGET:$SAVE_PATH, you probably need to run "kdumpctl propagate""  >&2
> return 1
> fi
>
> -- 
> 1.9.3