clad - Parallel SSH client
clad [options] <cluster> <command>
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.
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.
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
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 5.8.1 or better in the
PATH and requires JSON::PP (included as part of the Core as of Perl 5.14).
Limit the maximum number of simultaneous connections to
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
FILE2, etc. The files will automatically be removed when the command completes on the remote end. An example usage for this would be to install rpm packages:
% clad --file Database-Server-0.01-1.noarch.rp mycluster 'rpm -U $FILE1'
Print help and exit.
Print the version and exit.
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:
--- cluster: mycluster: - host1 - host2 myothercluster: - 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.
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.
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 default.
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.
A hash of inline scripts. The keys are the script name and the values are the script bodies. For example, with
--- script: dir_listing: #!/bin/bash for i in $( ls ); do echo item: $i done
You can get directory listing with
% clad cluster dir_listing
Here is an example configuration
--- env: PATH: /home/starscream/perl5/bin:/usr/local/bin:/usr/bin:/bin PERL5LIB: /home/starscream/perl5/lib cluster: mailservers: - mail1 - mail2 webservers: - www1 - www2 - www3 databases: - db1 - db2 - db3 - db4 alias: config_init: git clone git1:/cm/config-$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
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
In the configuration above, we have specified
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 local::lib.
% clad webservers -- perl -Mojo -E 'say g("mojolicio.us")->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 ]
For example, to initialize the configuration directory using the <config_init> alias:
--- alias: config_init: git clone git1:/cm/config-$CLUSTER.git ~/etc
% clad webservers config_init
...we can update using the
--- alias: config_update: cd ~/etc && git pull
% 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 disaster.
--- alias: config_destory: rm -rf ~/etc
% clad webservers config_destroy
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.
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 <email@example.com>
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.