[Pacemaker] Required resources for stateful clones

[Eamon Roque]

Hi,


>> On Thu, May 19, 2011 at 5:05 AM, Eamon Roque 
<Eamon.Roque at lex-com.net>wrote:

>> Hi,
>>
>> I've put together a cluster of two nodes running a databank without 
shared
>> storage. Both nodes replicate data between them, which is taken care of 
by
>> the databank itself.
>>
>> I have a resource for the databank and ip. I then created a stateful 
clone
>> from the databank resource. I created colocation rules joining the
>> databank-ms-clone and ip:
>>
>> node pgsqltest1
>> node pgsqltest2
>> primitive Postgres-IP ocf:heartbeat:IPaddr2 \
>>         params ip="10.19.57.234" cidr_netmask="32" \
>>         op monitor interval="30s" \
>>         meta is-managed="false"
>> primitive resPostgres ocf:heartbeat:pgsql \
>>         params pgctl="/opt/PostgreSQL/9.0/bin/pg_ctl"
>>pgdata="/opt/PostgreSQL/9.0/data" psql="/opt/PostgreSQL/9.0/bin/psql"
>> pgdba="postgres" \
>>         op monitor interval="1min" \
>>         meta is-managed="false"
>> ms msPostgres resPostgres \
>>         meta master-max="1" master-node-max="1" clone-max="2"
>> clone-node-max="1" notify="true" target-role="started"
>> colocation colPostgres inf: Postgres-IP msPostgres:Master
>> order ordPostgres inf: msPostgres:promote Postgres-IP:start
>> property $id="cib-bootstrap-options" \
>>         dc-version="1.1.2-2e096a41a5f9e184a1c1537c82c6da1093698eb5" \
>>         cluster-infrastructure="openais" \
>>         expected-quorum-votes="2" \
>>        stonith-enabled="false" \
>>        no-quorum-policy="ignore" \
>>         last-lrm-refresh="1302707146"
>> rsc_defaults $id="rsc-options" \
>>         resource-stickiness="200"
>> op_defaults $id="op_defaults-options" \
>>         record-pending="false"
>>
>> The normal postgres agent doesn't support this functionality, but I've 
put
>> together my own using the mysql agent as a model. Before running the 
script
>> through ocf-tester, I unmanage the postgres resource.
>>

> Could you show how you implemented promote/demote for pgsql?

Sure, let's start with the ultra-simple "promote" function:

#
# These variables are higher up in the file, but they will probably help 
with understanding the error of 
# my ways.

CRM_MASTER="${HA_SBIN_DIR}/crm_master"
ATTRD_UPDATER="${HA_SBIN_DIR}/attrd_updater"

pgsql_promote() {
        local output
        local rc
        local CHECK_PG_SQL
        local COMPLETE_STANDBY_QUERY
        local PROMOTE_SCORE_HIGH
        local MOD_PSQL_M_FORMAT


        PROMOTE_SCORE_HIGH=1000 
        CHECK_PG_SQL="SELECT pg_is_in_recovery()"
        MOD_PSQL_M_FORMAT="$OCF_RESKEY_psql -Atc"
        COMPLETE_STANDBY_QUERY="$MOD_PSQL_M_FORMAT \"$CHECK_PG_SQL\""

        output=$(su - $OCF_RESKEY_pgdba -c "$COMPLETE_STANDBY_QUERY" 2>&1)
        echo $output
 
        rc=$?
 
        case $output in
                f)
                        ocf_log debug "PostgreSQL Node is running in 
Master mode..."
                        return $OCF_RUNNING_MASTER
                ;;
 
                t)
                        ocf_log debug "PostgreSQL Node is in Hot_Standby 
mode..."
                        return $OCF_SUCCESS
                ;;

                *)
                        ocf_log err "Critical error in $CHECK_PG_SQL: 
$output"
                        return $OCF_ERR_GENERIC 
                ;;
        esac

#
# "Real" promotion is handled here.
# The trigger file is created and we check for "recovery.conf" on the 
host.
# If we can't find it, then the file will be copied from the HA-Config 
into postgres' data folder.
#

if ! touch $OCF_RESKEY_trigger_file; then
        ocf_log err "$OCF_RESKEY_trigger_file could not be created!"
        return $OCF_ERR_GENERIC
fi

if [ ! -f $OCF_RESKEY_recovery_conf ]; then
        ocf_log err "$OCF_RESKEY_recovery_conf doesn't exist!"
        cp $OCF_RESKEY_recovery_conf_ersatz $OCF_RESKEY_pgdata
        return $OCF_SUCCESS
fi

# If both file exist or can be created, then the failover fun can start.

ocf_log info "$OCF_RESKEY_trigger_file was created."
ocf_log info "$OCF_RESKEY_recovery_conf exists and can be copied to the 
correct location."

# Sometimes, the master needs a bit of time to take the reins. So...

while :
do
        pgsql_monitor warn
        rc=$?

        if [ $rc -eq $OCF_RUNNING_MASTER ]; then
                break;
        fi

        ocf_log debug "Postgres Server could not be promoted. Please 
wait..."
 
        sleep 1

done

ocf_log info "Postgres Server has been promoted. Please check on the 
previous master."

#################################
#Attributes Update:             #
#################################

$ATTRD_UPDATER -n $PGSQL_STATUS_NAME -v \"PRI\" || exit $(echo "Eh! 
Attrd_updater is not working!")

#############################################
# Resource stickiness pumped up to 1000 :  #
#############################################

$CRM_MASTER -v $PROMOTE_WERT_HOCH || exit $(echo "crm_master could not 
change the Master's status!")

############
# Success! #
############ 

return $OCF_SUCCESS

}

######################################################################################################

Thanks!

Éamon


>> Unfortunately, promote/demote doesn't work. ocf-tester tries to use the
>> "crm_attribute -N pgsql1 -n master-pgrql-replication-agent -l reboot -v
>> 100", but the (unmanaged) resources don't accept the score change.
>>
>> I'm pretty sure that I just need to be hit with a clue stick and would 
be
>> grateful for any help.
>>
>> Thanks,
>>
>> ?amon
>>



-- 
Serge Dubrouski.
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