Start jboss-cli only once

Question

I want to create a bash/shell script which monitors the JVM memory usage of Wildfly by using the jboss-cli Therefor I need to get the hosts and get the Wildfly servers per host in a for loop. However, starting/connecting the jboss-cli takes several seconds and stresses the CPU. This makes the script very slow. Sending commands in an interactive jboss-cli session is quite fast.

Is there a way to connect to the jboss-cli only once and send the input commands to that active session? I need the output of the commands to continue with the script.

Current script:

# List all hosts:
hosts="$(jboss-cli.sh -c --controller=servername:9990 --command=":read-children-names(child-type=host)" | grep "        " | awk '{print $1}' | sed 's/,//g' | sed 's/"//g')"
# Loop through hosts results:
for host in $hosts
{       
        #List all servers:
        servers="$(jboss-cli.sh -c --controller=servername:9990 --command="/host=$host:read-children-names(child-type=server)" | grep "        " | awk '{print $1}' | sed 's/,//g' | sed 's/"//g')"
        # Loop through server results:
        for server in $servers
        {
            # check if server is running:
            serverstate=$(jboss-cli.sh -c --controller=servername:9990 --command="/host=$host/server=$server:read-attribute(name=server-state)" | grep "result" | awk '{print $3}' | sed 's/"//g')

            if [ $serverstate = "running" ]
            then
                #Do a check etc. etc.
            fi
        }       
}

In addition to the starting post: there are 3 hosts, with each 50 Wildfly servers, so that currently means +/- 300 times creating a jboss-cli connection at the moment. — b100, Jun 18 '20 at 12:26

score 0 · Accepted Answer · answered Jun 18 '20 at 16:00

Had a similar problem. My solution is using coroutine in ksh and I don't know if it's possible in bash like your flag (but if ksh is installed you can still use it). At least it might gives you some pointers.

#!/bin/ksh

#connecting using coroutine -- Note the |& at the end
{JBOSS_HOME}/bin/jboss-cli.sh --connect --controller={Master_IP}:{Master_Port} --user={UID} --password={Password} |&
#sending request to coroutine
print -p "ls -l /host\n"
#Reading from corouting
while read -p answer; do
##Need to verify when stop reading -- after the prompt is back
    if [[ $answer != *domain*:* ]]; then
    ## If it's not an error, concatenate, space delimited, the response
        if [[ $answer == *WFLYCTL* ]]; then
            print "$(date +"%Y%m%d%H%M") - FATAL - Error detected - Exiting"
            print "$(date +"%Y%m%d%H%M") - Error detected : $answer"
            exit
        else
            Dummy+=$answer" "
        fi
    elif [[ locFlag -eq 1 ]]; then
        locFlag=0
        break
    else
        locFlag=1
    fi
done
##Response to array
SvrArray=( $Dummy )
##Do anything with the response, here just printing
for i in ${!SvrArray[@]}; do
        print "$i. ${SvrArray[$i]}"
done

Start jboss-cli only once

1 Answers1