Re: patch: sv check should wait when svrun is not ready

From: Colin Booth <>
Date: Mon, 16 Feb 2015 15:56:18 -0800

If you are running the sv check within a dependent service's run
script that was spawned first, the script will fail and runsv will
respawn it, with the call eventually succeeding once the required
service is up. This presumes that you start your scripts set -e or
/bin/sh -e of course, but there's no reason not to in this case.

If you're calling this from a daemon script that is outside of the
general supervision framework, you'll need to write a simple wait loop
in shell to wrap the sv call similar to what Case suggested. Something
like the following should do you:

while ! sv check $REQSVC > /dev/null
do echo "Waiting on required service $REQSVC"
sleep 1


But at that point, might as well just stick it into supervision and
let the dependent run script fail a few times before check passes.


On Mon, Feb 16, 2015 at 1:23 PM, Buck Evan <> wrote:
> Is there anything else I can do to get this considered for merge?
> On Mon, Feb 9, 2015 at 5:55 PM, Buck Evan <> wrote:
>> Essentially, if `sv check` is run too soon after `runsv` (or runit for
>> that matter), it will immediately fail without waiting for runsv to come
>> up. In my particular use case, runit is running inside a (detached) docker,
>> and I'm using `sv check` to wait for my dockerized service to be ready,
>> which I think is a good use case for `sv check`. Without this patch, I'm
>> forced to write some code which re-runs `sv check` if it fails before
>> $SVWAIT seconds, which sounds awfully like the behavior of sv-check itself.
>> You can demonstrate the problem I'm trying to describe like so:
>> #!/bin/bash
>> make
>> rm -rf myservice
>> mkdir -p myservice
>> ln -s /bin/cat myservice/run
>> ./runsv ./myservice/ >&/dev/null & ./sv check ./myservice/; echo $?; ./sv
>> check ./myservice/; echo $?
>> Output:
>> $ ./demo
>> warning: ./myservice/: unable to open supervise/ok: file does not exist
>> 1
>> ok: run: ./myservice/: (pid 65635) 0s
>> 0
>> Patch:
>> --- src/sv.c
>> +++ src/sv.c
>> _at_@ -213,7 +213,7 @@ int checkscript() {
>> int check(char *a) {
>> unsigned int pid;
>> - if ((r =svstatus_get()) == -1) return(-1);
>> + if ((r =svstatus_get()) == -1) return(0);
>> while (*a) {
>> if (r == 0) { if (*a == 'x') return(1); return(-1); }
>> pid =(unsigned char)svstatus[15];

"If the doors of perception were cleansed every thing would appear to
man as it is, infinite. For man has closed himself up, till he sees
all things thru' narrow chinks of his cavern."
  --  William Blake
Received on Mon Feb 16 2015 - 23:56:18 UTC

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