[ClusterLabs] Using "mandatory" startup order but avoiding depending clones from restart after member of parent clone fails

[Ken Gaillot]

On 02/09/2017 08:50 AM, Alejandro Comisario wrote:
> Ken, thanks for yor reply.
> 
> Since in our setup, we use active/active mysql clone, so i think that
> order is the only way to ensure what i want.
> So, simple question, making order "Advisory", and tiking into
> consideration that "maybe" keystone starts before mysql, making it fail
> because of database connecrion.
> 
> If i set on the keystone clone (and all the dependant clones)
> on-fail="restart" for start and monitor actions (of course setting the
> cib option start-failure-is-fatal=false ) to make sure that if it fails,
> it will restart till everything is ok.
> 
> would that make sense to "workaround" that ?
> 
> best.

Yes, that would work. The default is to fail up to 1,000,000 times, then
it will stop retrying on that node. Of course, you can clean up the
failure to start over (or set a failure-timeout to do that automatically).

> On Thu, Feb 9, 2017 at 12:18 AM, Ken Gaillot <kgaillot at redhat.com
> <mailto:kgaillot at redhat.com>> wrote:
> 
>     On 02/06/2017 05:25 PM, Alejandro Comisario wrote:
>     > guys, really happy to post my first doubt.
>     >
>     > i'm kinda having an "conceptual" issue that's bringing me, lots of
>     issues
>     > i need to ensure that order of starting resources are mandatory but
>     > that is causing me a huge issue, that is if just one of the members of
>     > a clone goes down and up (but not all members) all resources depending
>     > on it are restarted (wich is bad), my workaround is to set order as
>     > advisory, but that doesnt asure strict order startup.
>     >
>     > eg. clone_b runs on servers_B, and depends on clone_a that runs on
>     servers_A.
>     >
>     > I'll put an example on how i have everything defined between this
>     two clones.
>     >
>     > ### clone_A running on servers A (location rule)
>     > primitive p_mysql mysql-wss \
>     > op monitor timeout=55 interval=60 enabled=true on-fail=restart \
>     > op start timeout=475 interval=0 on-fail=restart \
>     > op stop timeout=175 interval=0 \
>     > params socket="/var/run/mysqld/mysqld.sock"
>     > pid="/var/run/mysqld/mysqld.pid" test_passwd="XXX" test_user=root \
>     > meta is-managed=true
>     >
>     > clone p_mysql-clone p_mysql \
>     > meta target-role=Started interleave=false globally-unique=false
>     >
>     > location mysql_location p_mysql-clone resource-discovery=never \
>     > rule -inf: galera ne 1
>     >
>     > ### clone_B running on servers B (location rule)
>     > primitive p_keystone apache \
>     > params configfile="/etc/apache2/apache2.conf" \
>     > op monitor on-fail=restart interval=60s timeout=60s \
>     > op start on-fail=restart interval=0 \
>     > meta target-role=Started migration-threshold=2 failure-timeout=60s
>     > resource-stickiness=300
>     >
>     > clone p_keystone-clone p_keystone \
>     > meta target-role=Started interleave=false globally-unique=false
>     >
>     > location keystone_location p_keystone-clone resource-discovery=never \
>     > rule -inf: keystone ne 1
>     >
>     > order p_clone-mysql-before-p_keystone INF: p_mysql-clone
>     p_keystone-clone:start
>     >
>     > Again just to make my point, if p_mysql-clone looses even one member
>     > of the clone, ONLY when that member gets back, all members of
>     > p_keystone-clone gets restarted, and thats NOT what i need, so if i
>     > change the order from mandatory to advisory, i get what i want
>     > regarding behaviour of what happens when instances of the clone comes
>     > and goes, but i loos the strictness of the startup order, which is
>     > critial for me.
>     >
>     > How can i fix this problem ?
>     > .. can i ?
> 
>     I don't think pacemaker can model your desired situation currently.
> 
>     In OpenStack configs that I'm familiar with, the mysql server (usually
>     galera) is a master-slave clone, and the constraint used is "promote
>     mysql then start keystone". That way, if a slave goes away and comes
>     back, it has no effect.