clad - Parallel SSH client


    version 1.11


     clad [options] <cluster> <command>
     clad --list
     clad --help


    Clad provides the ability to run the same command on several hosts at
    once. The output is displayed unbuffered as the various hosts run the
    command. The list of hosts is determined by reading a configuration
    file which may also contain command aliases and environment settings.



      Dry run, just show the command that would be executed and each host.


      Do not colorize the host names in the output.

    -l user

      Specify a login name for all ssh connections.


      Print out a lot of debugging information which may be useful in
      debugging issues with clad.


      Force clad to wait for the command to finish on each host before
      continuing to the next. This will be slower, but may be easier to
      read the output.

    --config name

      Specify the name of an alternate configuration. For example if you
      use --config MyClad then the configuration file ~/etc/MyClad.conf
      will be used instead of ~/etc/Clad.conf.


      Send the server code with the payload and feed into Perl on the
      remote end. This makes the total payload much larger, but it allows
      you to use clad with servers that do not have App::clad installed.
      The remote end must have Perl 5.6.1 or better in the PATH.

    --max number

      Limit the maximum number of simultaneous connections to number

    --file filename

      Copy files to the remote end as part of the payload. May be specified
      multiple times. The names of the files are available as environment
      variables FILE1, FILE2, etc. The files will automatically be removed
      on the remote end when the command completes. An example usage for
      this would be to install rpm packages:

       % clad --file Database-Server-0.01-1.noarch.rp mycluster 'rpm -U $FILE1'

    --dir directory

      Recursively copy the directory to the remote end as part of the
      payload. The name of the directory is available as an environment
      variable DIR. The directory will automatically be removed on the
      remote end when the command completes. For example if you are
      installing a directory full of rpm packages:

       % clad --dir ~/rpmbuild/RPMS/noarch mycluster 'rpm -U $DIR/*'


      Do not print out standard output and standard input, just the exit
      values or signals returned from each host.

    --log-dir dir

      Specify a directory to write log files to. Each host will have its
      own log file.


      Same as --log-dir, but the location is ~/clad/log.


      Purge any logs that have collected under your home directory from
      using the --log option.


      List the clusters and aliases defined in your configuration.


      Print help and exit.


      Print the version and exit.


    The configuration file is a Clustericious::Config style configuration
    file. See "EXAMPLES" for an example configuration. It contains these
    sections and configuration items:


    Environment hash to override environment variables on all hosts that
    run the command.


    Hash to define the clusters. This is a hash of lists, where the keys
    are the cluster names and the lists are the host names. For example:

         - host1
         - host2
         - host3
         - host4

    The old key (now deprecated) clusters is also recognized, if cluster is
    not specified. This deprecated key will be removed on or after January
    31 2016.

    You can use a single hostname not in the cluster section to specify a
    cluster of one host, so long as it is a legal hostname understood by


    Hash of aliases. This is a useful place to specify common shortcuts.
    The values in this hash may be either strings or lists, allowing you to
    use the list or scalar form of system.

    The old key (now deprecated) aliases is also recognized, if alias is
    not specified. This deprecated key will be removed on or after January
    31 2016.


    clad runs on both the client and the server. This specifies the command
    used to communicate with the client on the server end. Unless you are
    testing clad you probably won't need to change this.


    Include the server code as part of the payload. This is useful for
    hosts that do not already have App::clad installed. This is the same as
    the --fat option above.


    The command to execute on the server side when using the --fat command
    line option or the fat configuration option. The default is simply


    This is the ssh command to use on the client side. It is ssh by


    These are the ssh options used when opening a connection to the server.
    The default may change as needed.


    Extra ssh command line options to be added after ssh_options. If you
    just want to add a few options without replacing the existing set, this
    is the way to go.


    A list of colors as understood by Term::ANSIColor which are used in
    alteration for each host to help separate the output visually.


    Color to use if clad determined the remote call failed

    exit with non zero

    killed by signal

    failed to start (usually due to a bad command)

    The default is bold red.


    Color to use for output to standard error. The default is bold yellow.


    A hash of inline scripts. The keys are the script name and the values
    are the script bodies. For example, with

         for i in $( ls ); do
           echo item: $i

    You can get directory listing with

     % clad cluster dir_listing


    Here is an example configuration

       PATH: /home/starscream/perl5/bin:/usr/local/bin:/usr/bin:/bin
       PERL5LIB: /home/starscream/perl5/lib
         - mail1
         - mail2
         - www1
         - www2
         - www3
         - db1
         - db2
         - db3
         - db4
       config_init: git clone git1:/cm/config-$CLUSTER.git ~/etc
       config_update: cd ~/etc && git pull
       config_destory: rm -rf ~/etc


    To find the uptime of the mailservers:

     % clad webservers uptime
     [mail1 out ]  21:27:04 up 4 days, 12:22,  0 users,  load average: 0.96, 1.01, 1.04
     [mail2 out ]  21:24:09 up 93 days, 12:52,  0 users,  load average: 1.25, 1.33, 1.29

    To find the uptime of all servers in any cluster:

     % clad mailservers,webservers,databases
     [mail1 out ]  21:27:04 up 4 days, 12:22,  0 users,  load average: 0.96, 1.01, 1.04
     [mail2 out ]  21:24:09 up 93 days, 12:52,  0 users,  load average: 1.25, 1.33, 1.29
     [www1  out ]  21:24:37 up 93 days, 12:52,  0 users,  load average: 2.60, 2.34, 2.21
     [www2  out ]  21:23:06 up 93 days, 12:51,  0 users,  load average: 0.60, 0.50, 0.50
     [www3  out ]  21:24:05 up 93 days, 12:52,  0 users,  load average: 3.99, 3.62, 3.55
     [db1   out ]  21:24:53 up 93 days, 12:47,  0 users,  load average: 11.71, 12.15, 12.23
     [db2   out ]  21:26:07 up 93 days, 12:52,  0 users,  load average: 14.13, 13.91, 13.05
     [db3   out ]  21:29:06 up 93 days, 12:53,  0 users,  load average: 1.99, 1.59, 1.14
     [db4   out ]  21:24:55 up 93 days, 12:48,  0 users,  load average: 4.99, 4.83, 4.03

    (note that the output in this example is displayed in order, though in
    practice it will usually be jumbled

 log into hosts with different user

    By default clad will login to the remote servers with what ever user is
    default for ssh (this is usually determined by the local user and / or
    the ssh configuration). You can use the -l option to specify a user
    name for all clusters in the command

     % clad -l foo mailservers,webservers,databases whoami
     [mail1 out ] foo
     [mail2 out ] foo
     [www1  out ] foo
     [www2  out ] foo
     [www3  out ] foo
     [db1   out ] foo
     [db2   out ] foo
     [db3   out ] foo
     [db4   out ] foo

    or you can prefix individual clusters with a user name using the @

     % clad foo@mailservers,bar@webservers,baz@database whoami
     [mail1 out ] foo
     [mail2 out ] foo
     [www1  out ] bar
     [www2  out ] bar
     [www3  out ] bar
     [db1   out ] baz
     [db2   out ] baz
     [db3   out ] baz
     [db4   out ] baz

 running Perl remotely

    In the configuration above, we have specified PATH and PERL5LIB
    environment variables to work with the modules build for local::lib on
    each host (the actual configuration is probably a little more
    complicated), so we can use modules that we have installed in

     % clad webservers -- perl -Mojo -E 'say g("")->dom->at("title")->text'
     [www1 out ]
     [www1 out ]       Mojolicious - Perl real-time web framework
     [www1 out ]
     [www2 out ]
     [www2 out ]       Mojolicious - Perl real-time web framework
     [www2 out ]
     [www3 out ]
     [www3 out ]       Mojolicious - Perl real-time web framework
     [www3 out ]

 pulling remote configuration using git

    Clustericious servers and client use configuration files that are
    usually stored in ~/etc. We usually manage these configurations on a
    cluster by cluster basis using git, and deploy them using clad.

    For example, to initialize the configuration directory using the
    <config_init> alias:

       config_init: git clone git1:/cm/config-$CLUSTER.git ~/etc

    and run:

     % clad webservers config_init

    ...we can update using the config_update alias:

       config_update: cd ~/etc && git pull

    and run:

     % clad webservers config_update

    ...and if the configuration becomes hosed, we can remove it and start
    over. Since the master configuration is stored in git this may not be

       config_destory: rm -rf ~/etc

    and run:

     % clad webservers config_destroy

 using shell

    clad runs the command on the remote end using the same exact arguments
    as you pass it on the client side. That means that it uses either the
    single argument or list version of system depending on input. That
    means that if you want to use shell logic, pipes or redirection, you
    need to use the single argument version! For example:

     % clad webservers cd ~/etc && git pull    # WRONG !
     % clad webservers 'cd ~/etc && git pull'  # RIGHT !

    Sometimes if you don't want to worry about the escaping of meta
    characters the list version will be more appropriate

     % clad webservers perl -E 'say "hi there"'



    This environment variable is set to the cluster name from the
    configuration file on each node that the command is run. The deprecated
    CLUSTER is also set, though that may be removed in a future version.


    You can override the default values for the --fat, --server_command and
    --fat_server_command at install time using options to Build.PL.

     perl Build.PL --clad_fat \
                   --clad_server_command /usr/local/bin/perl \
                   --server_command /usr/local/bin/perl /usr/local/bin/clad --server

    In this example, we specify fully qualified pathnames for Perl and
    clad, which may be what you want in environments where the system Perl
    (usually installed in /usr/bin/perl) comes before the Perl that you
    want to use.


    Clustericious::Admin and clad require an AnyEvent event loop that
    allows entering the event loop by calling recv on a condition variable.
    This is not supported by all AnyEvent event loops and is discouraged by
    the AnyEvent documentation for CPAN modules, though most of the
    important event loops, such as EV and the pure perl implementation that
    comes with AnyEvent DO support this behavior.


    Graham Ollis <>


    This software is copyright (c) 2015 by Graham Ollis.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.