Akka/Scala example source code file (reference.conf)

This example Akka source code file (reference.conf) 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.

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The reference.conf Akka example source code

#####################################
# Akka Remote Reference Config File #
#####################################

# This is the reference config file that contains all the default settings.
# Make your edits/overrides in your application.conf.

# comments about akka.actor settings left out where they are already in akka-
# actor.jar, because otherwise they would be repeated in config rendering.

akka {

  actor {

    serializers {
      akka-containers = "akka.remote.serialization.MessageContainerSerializer"
      proto = "akka.remote.serialization.ProtobufSerializer"
      daemon-create = "akka.remote.serialization.DaemonMsgCreateSerializer"
    }


    serialization-bindings {
      # Since com.google.protobuf.Message does not extend Serializable but
      # GeneratedMessage does, need to use the more specific one here in order
      # to avoid ambiguity
      "akka.actor.ActorSelectionMessage" = akka-containers
      "com.google.protobuf.GeneratedMessage" = proto
      "akka.remote.DaemonMsgCreate" = daemon-create
    }

    deployment {

      default {

        # if this is set to a valid remote address, the named actor will be
        # deployed at that node e.g. "akka.tcp://sys@host:port"
        remote = ""

        target {

          # A list of hostnames and ports for instantiating the children of a
          # router
          #   The format should be on "akka.tcp://sys@host:port", where:
          #    - sys is the remote actor system name
          #    - hostname can be either hostname or IP address the remote actor
          #      should connect to
          #    - port should be the port for the remote server on the other node
          # The number of actor instances to be spawned is still taken from the
          # nr-of-instances setting as for local routers; the instances will be
          # distributed round-robin among the given nodes.
          nodes = []

        }
      }
    }
  }

  remote {

    ### General settings

    # Timeout after which the startup of the remoting subsystem is considered
    # to be failed. Increase this value if your transport drivers (see the
    # enabled-transports section) need longer time to be loaded.
    startup-timeout = 10 s

    # Timout after which the graceful shutdown of the remoting subsystem is
    # considered to be failed. After the timeout the remoting system is
    # forcefully shut down. Increase this value if your transport drivers
    # (see the enabled-transports section) need longer time to stop properly.
    shutdown-timeout = 10 s

    # Before shutting down the drivers, the remoting subsystem attempts to flush
    # all pending writes. This setting controls the maximum time the remoting is
    # willing to wait before moving on to shut down the drivers.
    flush-wait-on-shutdown = 2 s

    # Reuse inbound connections for outbound messages
    use-passive-connections = on

    # Controls the backoff interval after a refused write is reattempted.
    # (Transports may refuse writes if their internal buffer is full)
    backoff-interval = 5 ms

    # Acknowledgment timeout of management commands sent to the transport stack.
    command-ack-timeout = 30 s

    # If set to a nonempty string remoting will use the given dispatcher for
    # its internal actors otherwise the default dispatcher is used. Please note
    # that since remoting can load arbitrary 3rd party drivers (see
    # "enabled-transport" and "adapters" entries) it is not guaranteed that
    # every module will respect this setting.
    use-dispatcher = "akka.remote.default-remote-dispatcher"

    ### Security settings

    # Enable untrusted mode for full security of server managed actors, prevents
    # system messages to be send by clients, e.g. messages like 'Create',
    # 'Suspend', 'Resume', 'Terminate', 'Supervise', 'Link' etc.
    untrusted-mode = off
    
    # When 'untrusted-mode=on' inbound actor selections are by default discarded.
    # Actors with paths defined in this white list are granted permission to receive actor
    # selections messages. 
    # E.g. trusted-selection-paths = ["/user/receptionist", "/user/namingService"]   
    trusted-selection-paths = []

    # Should the remote server require that its peers share the same
    # secure-cookie (defined in the 'remote' section)? Secure cookies are passed
    # between during the initial handshake. Connections are refused if the initial
    # message contains a mismatching cookie or the cookie is missing.
    require-cookie = off

    # Generate your own with the script availbale in
    # '$AKKA_HOME/scripts/generate_config_with_secure_cookie.sh' or using
    # 'akka.util.Crypt.generateSecureCookie'
    secure-cookie = ""

    ### Logging

    # If this is "on", Akka will log all inbound messages at DEBUG level,
    # if off then they are not logged
    log-received-messages = off

    # If this is "on", Akka will log all outbound messages at DEBUG level,
    # if off then they are not logged
    log-sent-messages = off

    # Sets the log granularity level at which Akka logs remoting events. This setting
    # can take the values OFF, ERROR, WARNING, INFO, DEBUG, or ON. For compatibility
    # reasons the setting "on" will default to "debug" level. Please note that the effective
    # logging level is still determined by the global logging level of the actor system:
    # for example debug level remoting events will be only logged if the system
    # is running with debug level logging.
    # Failures to deserialize received messages also fall under this flag.
    log-remote-lifecycle-events = on

    # Logging of message types with payload size in bytes larger than
    # this value. Maximum detected size per message type is logged once,
    # with an increase threshold of 10%.
    # By default this feature is turned off. Activate it by setting the property to
    # a value in bytes, such as 1000b. Note that for all messages larger than this
    # limit there will be extra performance and scalability cost.
    log-frame-size-exceeding = off
    
    # Log warning if the number of messages in the backoff buffer in the endpoint
    # writer exceeds this limit. It can be disabled by setting the value to off.
    log-buffer-size-exceeding = 50000

    ### Failure detection and recovery

    # Settings for the failure detector to monitor connections.
    # For TCP it is not important to have fast failure detection, since
    # most connection failures are captured by TCP itself. 
    transport-failure-detector {

      # FQCN of the failure detector implementation.
      # It must implement akka.remote.FailureDetector and have
      # a public constructor with a com.typesafe.config.Config and
      # akka.actor.EventStream parameter.
      implementation-class = "akka.remote.DeadlineFailureDetector"

      # How often keep-alive heartbeat messages should be sent to each connection.
      heartbeat-interval = 4 s

      # Number of potentially lost/delayed heartbeats that will be
      # accepted before considering it to be an anomaly.
      # A margin to the `heartbeat-interval` is important to be able to survive sudden,
      # occasional, pauses in heartbeat arrivals, due to for example garbage collect or
      # network drop.
      acceptable-heartbeat-pause = 20 s
    }

    # Settings for the Phi accrual failure detector (http://ddg.jaist.ac.jp/pub/HDY+04.pdf
    # [Hayashibara et al]) used for remote death watch.
    watch-failure-detector {

      # FQCN of the failure detector implementation.
      # It must implement akka.remote.FailureDetector and have
      # a public constructor with a com.typesafe.config.Config and
      # akka.actor.EventStream parameter.
      implementation-class = "akka.remote.PhiAccrualFailureDetector"

      # How often keep-alive heartbeat messages should be sent to each connection.
      heartbeat-interval = 1 s

      # Defines the failure detector threshold.
      # A low threshold is prone to generate many wrong suspicions but ensures
      # a quick detection in the event of a real crash. Conversely, a high
      # threshold generates fewer mistakes but needs more time to detect
      # actual crashes.
      threshold = 10.0

      # Number of the samples of inter-heartbeat arrival times to adaptively
      # calculate the failure timeout for connections.
      max-sample-size = 200

      # Minimum standard deviation to use for the normal distribution in
      # AccrualFailureDetector. Too low standard deviation might result in
      # too much sensitivity for sudden, but normal, deviations in heartbeat
      # inter arrival times.
      min-std-deviation = 100 ms

      # Number of potentially lost/delayed heartbeats that will be
      # accepted before considering it to be an anomaly.
      # This margin is important to be able to survive sudden, occasional,
      # pauses in heartbeat arrivals, due to for example garbage collect or
      # network drop.
      acceptable-heartbeat-pause = 10 s


      # How often to check for nodes marked as unreachable by the failure
      # detector
      unreachable-nodes-reaper-interval = 1s

      # After the heartbeat request has been sent the first failure detection
      # will start after this period, even though no heartbeat mesage has
      # been received.
      expected-response-after = 3 s

    }

    # After failed to establish an outbound connection, the remoting will mark the
    # address as failed. This configuration option controls how much time should
    # be elapsed before reattempting a new connection. While the address is
    # gated, all messages sent to the address are delivered to dead-letters.
    # Since this setting limits the rate of reconnects setting it to a
    # very short interval (i.e. less than a second) may result in a storm of
    # reconnect attempts.
    retry-gate-closed-for = 5 s

    # After catastrophic communication failures that result in the loss of system
    # messages or after the remote DeathWatch triggers the remote system gets
    # quarantined to prevent inconsistent behavior.
    # This setting controls how long the Quarantine marker will be kept around
    # before being removed to avoid long-term memory leaks.
    # WARNING: DO NOT change this to a small value to re-enable communication with
    # quarantined nodes. Such feature is not supported and any behavior between
    # the affected systems after lifting the quarantine is undefined.
    prune-quarantine-marker-after = 5 d

    # This setting defines the maximum number of unacknowledged system messages
    # allowed for a remote system. If this limit is reached the remote system is
    # declared to be dead and its UID marked as tainted.
    system-message-buffer-size = 1000

    # This setting defines the maximum idle time after an individual
    # acknowledgement for system messages is sent. System message delivery
    # is guaranteed by explicit acknowledgement messages. These acks are
    # piggybacked on ordinary traffic messages. If no traffic is detected
    # during the time period configured here, the remoting will send out
    # an individual ack.
    system-message-ack-piggyback-timeout = 0.3 s

    # This setting defines the time after internal management signals
    # between actors (used for DeathWatch and supervision) that have not been
    # explicitly acknowledged or negatively acknowledged are resent.
    # Messages that were negatively acknowledged are always immediately
    # resent.
    resend-interval = 2 s

    # WARNING: this setting should not be not changed unless all of its consequences
    # are properly understood which assumes experience with remoting internals
    # or expert advice.
    # This setting defines the time after redelivery attempts of internal management
    # signals are stopped to a remote system that has been not confirmed to be alive by
    # this system before.
    initial-system-message-delivery-timeout = 3 m

    ### Transports and adapters

    # List of the transport drivers that will be loaded by the remoting.
    # A list of fully qualified config paths must be provided where
    # the given configuration path contains a transport-class key
    # pointing to an implementation class of the Transport interface.
    # If multiple transports are provided, the address of the first
    # one will be used as a default address.
    enabled-transports = ["akka.remote.netty.tcp"]

    # Transport drivers can be augmented with adapters by adding their
    # name to the applied-adapters setting in the configuration of a
    # transport. The available adapters should be configured in this
    # section by providing a name, and the fully qualified name of
    # their corresponding implementation. The class given here
    # must implement akka.akka.remote.transport.TransportAdapterProvider
    # and have public constructor without parameters.
    adapters {
      gremlin = "akka.remote.transport.FailureInjectorProvider"
      trttl = "akka.remote.transport.ThrottlerProvider"
    }

    ### Default configuration for the Netty based transport drivers

    netty.tcp {
      # The class given here must implement the akka.remote.transport.Transport
      # interface and offer a public constructor which takes two arguments:
      #  1) akka.actor.ExtendedActorSystem
      #  2) com.typesafe.config.Config
      transport-class = "akka.remote.transport.netty.NettyTransport"

      # Transport drivers can be augmented with adapters by adding their
      # name to the applied-adapters list. The last adapter in the
      # list is the adapter immediately above the driver, while
      # the first one is the top of the stack below the standard
      # Akka protocol
      applied-adapters = []

      transport-protocol = tcp

      # The default remote server port clients should connect to.
      # Default is 2552 (AKKA), use 0 if you want a random available port
      # This port needs to be unique for each actor system on the same machine.
      port = 2552

      # The hostname or ip to bind the remoting to,
      # InetAddress.getLocalHost.getHostAddress is used if empty
      hostname = ""

      # Enables SSL support on this transport
      enable-ssl = false

      # Sets the connectTimeoutMillis of all outbound connections,
      # i.e. how long a connect may take until it is timed out
      connection-timeout = 15 s

      # If set to "<id.of.dispatcher>" then the specified dispatcher
      # will be used to accept inbound connections, and perform IO. If "" then
      # dedicated threads will be used.
      # Please note that the Netty driver only uses this configuration and does
      # not read the "akka.remote.use-dispatcher" entry. Instead it has to be
      # configured manually to point to the same dispatcher if needed.
      use-dispatcher-for-io = ""

      # Sets the high water mark for the in and outbound sockets,
      # set to 0b for platform default
      write-buffer-high-water-mark = 0b

      # Sets the low water mark for the in and outbound sockets,
      # set to 0b for platform default
      write-buffer-low-water-mark = 0b

      # Sets the send buffer size of the Sockets,
      # set to 0b for platform default
      send-buffer-size = 256000b

      # Sets the receive buffer size of the Sockets,
      # set to 0b for platform default
      receive-buffer-size = 256000b

      # Maximum message size the transport will accept, but at least
      # 32000 bytes.
      # Please note that UDP does not support arbitrary large datagrams,
      # so this setting has to be chosen carefully when using UDP.
      # Both send-buffer-size and receive-buffer-size settings has to
      # be adjusted to be able to buffer messages of maximum size.
      maximum-frame-size = 128000b

      # Sets the size of the connection backlog
      backlog = 4096

      # Enables the TCP_NODELAY flag, i.e. disables Nagle’s algorithm
      tcp-nodelay = on

      # Enables TCP Keepalive, subject to the O/S kernel’s configuration
      tcp-keepalive = on

      # Enables SO_REUSEADDR, which determines when an ActorSystem can open
      # the specified listen port (the meaning differs between *nix and Windows)
      # Valid values are "on", "off" and "off-for-windows"
      # due to the following Windows bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4476378
      # "off-for-windows" of course means that it's "on" for all other platforms
      tcp-reuse-addr = off-for-windows

      # Used to configure the number of I/O worker threads on server sockets
      server-socket-worker-pool {
        # Min number of threads to cap factor-based number to
        pool-size-min = 2

        # The pool size factor is used to determine thread pool size
        # using the following formula: ceil(available processors * factor).
        # Resulting size is then bounded by the pool-size-min and
        # pool-size-max values.
        pool-size-factor = 1.0

        # Max number of threads to cap factor-based number to
        pool-size-max = 2
      }

      # Used to configure the number of I/O worker threads on client sockets
      client-socket-worker-pool {
        # Min number of threads to cap factor-based number to
        pool-size-min = 2

        # The pool size factor is used to determine thread pool size
        # using the following formula: ceil(available processors * factor).
        # Resulting size is then bounded by the pool-size-min and
        # pool-size-max values.
        pool-size-factor = 1.0

        # Max number of threads to cap factor-based number to
        pool-size-max = 2
      }


    }

    netty.udp = ${akka.remote.netty.tcp}
    netty.udp {
      transport-protocol = udp
    }

    netty.ssl = ${akka.remote.netty.tcp}
    netty.ssl = {
      # Enable SSL/TLS encryption.
      # This must be enabled on both the client and server to work.
      enable-ssl = true

      security {
        # This is the Java Key Store used by the server connection
        key-store = "keystore"

        # This password is used for decrypting the key store
        key-store-password = "changeme"

        # This password is used for decrypting the key
        key-password = "changeme"

        # This is the Java Key Store used by the client connection
        trust-store = "truststore"

        # This password is used for decrypting the trust store
        trust-store-password = "changeme"

        # Protocol to use for SSL encryption, choose from:
        # Java 6 & 7:
        #   'SSLv3', 'TLSv1'
        # Java 7:
        #   'TLSv1.1', 'TLSv1.2'
        protocol = "TLSv1"

        # Example: ["TLS_RSA_WITH_AES_128_CBC_SHA", "TLS_RSA_WITH_AES_256_CBC_SHA"]
        # You need to install the JCE Unlimited Strength Jurisdiction Policy
        # Files to use AES 256.
        # More info here:
        # http://docs.oracle.com/javase/7/docs/technotes/guides/security/SunProviders.html#SunJCEProvider
        enabled-algorithms = ["TLS_RSA_WITH_AES_128_CBC_SHA"]

        # There are three options, in increasing order of security:
        # "" or SecureRandom => (default)
        # "SHA1PRNG" => Can be slow because of blocking issues on Linux
        # "AES128CounterSecureRNG" => fastest startup and based on AES encryption
        # algorithm
        # "AES256CounterSecureRNG"
        # The following use one of 3 possible seed sources, depending on
        # availability: /dev/random, random.org and SecureRandom (provided by Java)
        # "AES128CounterInetRNG"
        # "AES256CounterInetRNG" (Install JCE Unlimited Strength Jurisdiction
        # Policy Files first)
        # Setting a value here may require you to supply the appropriate cipher
        # suite (see enabled-algorithms section above)
        random-number-generator = ""
      }
    }

    ### Default configuration for the failure injector transport adapter

    gremlin {
      # Enable debug logging of the failure injector transport adapter
      debug = off
    }

    ### Default dispatcher for the remoting subsystem

    default-remote-dispatcher {
      type = Dispatcher
      executor = "fork-join-executor"
      fork-join-executor {
        # Min number of threads to cap factor-based parallelism number to
        parallelism-min = 2
        parallelism-max = 2
      }
    }
    
    backoff-remote-dispatcher {
      type = Dispatcher
      executor = "fork-join-executor"
      fork-join-executor {
        # Min number of threads to cap factor-based parallelism number to
        parallelism-min = 2
        parallelism-max = 2
      }
    }


  }

}