Akka/Scala example source code file (akka-cluster)

This example Akka source code file (akka-cluster) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

actor_system_url, asks, checking, host, jmx_client, querying, self, sends, url, usage

The akka-cluster Akka example source code

#!/bin/bash

# ============== Akka Cluster Administration Tool ==============
#
# This script is meant to be used from within the Akka distribution.
#
# Add these options to the sbt or startup script:
#   java \
#      -Dcom.sun.management.jmxremote.port=9999 \
#      -Dcom.sun.management.jmxremote.ssl=false \
#      -Dcom.sun.management.jmxremote.authenticate=false \
#      ...
# ==============================================================

# FIXME support authentication? if so add: -Dcom.sun.management.jmxremote.password.file=<path to file> AND tweak this script to support it (arg need 'user:passwd' instead of '-')

declare AKKA_HOME="$(cd "$(cd "$(dirname "$0")"; pwd -P)"/..; pwd)"

SELF=`basename $0` # script name
HOST=$1            # cluster node to talk to through JMX
PORT=$2

shift 2

JMX_CLIENT="java -jar $AKKA_HOME/bin/jmxsh-R5.jar -h $HOST -p $PORT /dev/fd/0"

function invoke() {
  echo jmx_invoke -m akka:type=Cluster "$@" | $JMX_CLIENT
}

function get() {
  echo "puts [jmx_get -m akka:type=Cluster \"$1\"]" | $JMX_CLIENT
}

function ensureNodeIsRunningAndAvailable {
    REPLY=$(get Available) # redirects STDERR to STDOUT before capturing it
    if [[ "$REPLY" != *true ]]; then
        echo "Akka cluster node is not available on $HOST, due to $REPLY"
        exit 1
    fi
}

# switch on command
case "$1" in

    join)
        if [ $# -ne 2 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> join <node-url-to-join>"
            exit 1
        fi

        ACTOR_SYSTEM_URL=$2
        echo "$HOST is JOINING cluster node $ACTOR_SYSTEM_URL"
        invoke join $ACTOR_SYSTEM_URL
        ;;

    leave)
        if [ $# -ne 2 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> leave <node-url-to-join>"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        ACTOR_SYSTEM_URL=$2
        echo "Scheduling $ACTOR_SYSTEM_URL to LEAVE cluster"
        invoke leave $ACTOR_SYSTEM_URL
        ;;

    down)
        if [ $# -ne 2 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> down <node-url-to-join>"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        ACTOR_SYSTEM_URL=$2
        echo "Marking $ACTOR_SYSTEM_URL as DOWN"
        invoke down $ACTOR_SYSTEM_URL
        ;;

    member-status)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> member-status"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Querying member status for $HOST"
        get MemberStatus
        ;;

    cluster-status)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> cluster-status"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Querying cluster status"
        get ClusterStatus
        ;;

    members)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> members"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Querying members"
        get Members
        ;;

    unreachable)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> unreachable"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Querying unreachable members"
        get Unreachable
        ;;

    leader)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> leader"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Checking leader status"
        get Leader
        ;;

    is-singleton)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> is-singleton"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Checking for singleton cluster"
        get Singleton
        ;;

    is-available)
        if [ $# -ne 1 ]; then
            echo "Usage: $SELF <node-hostname> <jmx-port> is-available"
            exit 1
        fi

        ensureNodeIsRunningAndAvailable

        echo "Checking if member node on $HOST is AVAILABLE"
        get Available
        ;;

    *)
        printf "Usage: bin/$SELF <node-hostname> <jmx-port> <command> ...\n"
        printf "\n"
        printf "Supported commands are:\n"
        printf "%26s - %s\n" "join <node-url>"   "Sends request a JOIN node with the specified URL"
        printf "%26s - %s\n" "leave <node-url>"  "Sends a request for node with URL to LEAVE the cluster"
        printf "%26s - %s\n" "down <node-url>"   "Sends a request for marking node with URL as DOWN"
        printf "%26s - %s\n" member-status       "Asks the member node for its current status"
        printf "%26s - %s\n" members             "Asks the cluster for addresses of current members"
        printf "%26s - %s\n" unreachable         "Asks the cluster for addresses of unreachable members"
        printf "%26s - %s\n" cluster-status      "Asks the cluster for its current status (member ring, unavailable nodes, meta data etc.)"
        printf "%26s - %s\n" leader              "Asks the cluster who the current leader is"
        printf "%26s - %s\n" is-singleton        "Checks if the cluster is a singleton cluster (single node cluster)"
        printf "%26s - %s\n" is-available        "Checks if the member node is available"
        printf "Where the <node-url> should be on the format of 'akka.tcp://actor-system-name@hostname:port'\n"
        printf "\n"
        printf "Examples: bin/$SELF localhost 9999 is-available\n"
        printf "          bin/$SELF localhost 9999 join akka.tcp://MySystem@darkstar:2552\n"
        printf "          bin/$SELF localhost 9999 cluster-status\n"
        exit 1
        ;;
esac