Description

rcmd (remote command) is a command line utility written in Ruby for executing the same command on multiple systems through ssh. This is done by assigning a host to a thread and creating the ssh sessions in those threads.

Features

Command line switch for setting number of threads to be used at a time. (Default is 4)
A comma seperated list of hosts piped from another command can be used as the node list.
Username can be specified. (Default is root. Requires valid ssh-key in ~/.ssh)
Output shows which host the output is from
Stdout can be suppressed, only allowing for stderr to be shown
Usage of Regex for generating the host list
Support for SQLite3, MySql/MariaDB and PostgreSQL queries for generating host list

Installation

rcmd is available as a gem and kan be installed with gem install rcmd

Usage Examples

Help Screen

Usage: rcmd [options]
    -u, --username username          Username for SSH connections
    -n, --nodes x,y,z                Comma seperated list of nodes. use '-' for a space seperated list piped from another command
    -r, --regexp regex               Use Regex to build host list (ruby regexp)
    -t, --threads threads            Number of threads to run
    -c, --command <command>          Quoted string containing the command to be run
    -q, --quiet                      Suppress stdout of commands.  stderr will still be displayed
    -v, --version                    Print what version of the command is in use
    -D, --debug                      Print debug information

Database Options
    -C, --create-config              Create template dbconfig file in ~/.rcmd
    -T, --type server-type           Database query on server type
    -H, --host hostname-pattern      Database query on hostname (sql like query)
    -O, --os operating-system        Database query on Operating System string

Specifying nodes manually

Specifying a comma seperated list of hosts and timing the total execution time.

daibhidh@darkstar:~/$ time rcmd -n node1,node2,node3,node4 -c 'cat /etc/redhat-release'
node2 :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node1 :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node4 :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)
node3 :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)


real    0m2.749s
user    0m0.272s
sys     0m0.050s

Piping list of nodes

Using the hammer cli to get a list of hosts from a RedHat Satellite and providing it to rcmd as the node list.

daibhidh@darkstar:~/$ hammer --output base host list --organization org | awk '/Name:/ {print $2}' | rcmd -n - -c 'cat /etc/redhat-release'
node1.example.com :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node3.example.com :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)
node2.example.com :: Red Hat Enterprise Linux ComputeNode release 6.8 (Santiago)
node4.example.com :: Red Hat Enterprise Linux ComputeNode release 6.9 (Santiago)

Using regex to build node list

daibhidh@darkstar:~/$ rcmd -r 'node([1-9]|1[1-2])$' -c 'hostname -f'
node2 :: node2.example.com
node1 :: node1.example.com
node4 :: node4.example.com
node3 :: node3.example.com
node5 :: node5.example.com
node6 :: node6.example.com
node8 :: node8.example.com
node7 :: node7.example.com
node11 :: CONNECT ERROR :: Unable to connect to host!
node9 :: node9.example.com
node12 :: node12.example.com

Database backend support

The database backend support is provided by ActiveRecord and thus compatible with databases which are supported by ActiveRecord. Out of the box mysql2, sqlite3 and postgresql work. To use another database backend then you will need to download the source, add it to the rcmd.gemspec file, and correct the 'requires' in lib/rcmd/db.rb accordingly.

I tried having all of types in there but the dependency requirements became too great, both within Ruby and development libraries on the system.

To set up the database backend run rcmd with the '-C' switch first. This will create a database configuration file in ~/.rcmd named dbconfig.yml. In this file you can specify the adapter, and various other soptions for the database backend. For the queries to work properly, the :host_field: MUST be set so the command knows what column contains the host name.

Two optional fields exist as well, which are type_field and os_field. While these are meant to represent "Server type (I.e. Web, DB, etc) and Operating System Name/version, you can map these to whatever fields you would like to be able to sort by. If these fields are not specified then using the associated command line options will result in a run time error.

To minimize the size and possible issues with various backend adapters, no adapters are listed/installed when installing this Gem. It is up to you to install the correct adapter for the database you are wanting to connect to.

The '-T' and '-O' options use strict matching in their queries where as the '-H' option uses a 'LIKE' query.

Database backend examples

Hostname query (Match all systems whose hostname starts with node and contains at least two additional charectors):

daibhidh@darkstar:~/$ rcmd -H 'node%_' -c 'hostname -f'
node20 :: node20.example.com
node10 :: node10.example.com
node12 :: node12.example.com
node13 :: node13.example.com
node15 :: node15.example.com
node16 :: node16.example.com
node18 :: node18.example.com
node17 :: node17.example.com
node11 :: node11.example.com
node19 :: node19.example.com
node14 :: node14.example.com

Type query (Match all hosts listed as web servers):

daibhidh@darkstar:~/$ rcmd -T 'web' -c 'hostname -f'
node11 :: node11.example.com
node19 :: node19.example.com
node14 :: node14.example.com

OS query (Match all hosts listed as running slackware):

daibhidh@darkstar:~/$ rcmd -o 'slackware' -c 'hostname -f'
node10 :: node10.example.com
node12 :: node12.example.com
node18 :: node18.example.com
node17 :: node17.example.com
node11 :: node11.example.com

Database Issues

Due to some Operating systems forcing older Ruby versions (RedHat, CentOS, Mac OS X) rcmd will not install properly on these hosts. You can either manually install a newer version of Ruby (>= 2.2.2) or you can try to install activerecord and activesuppert versions 4.2.6. This might work but I have not fully tested it as of yet.

Development

If you are wanting to modify the code by all means do so. If you clone this repository you can then run bundle install to install the dependencies needed. Tests are performed with rspec and can be run with rake.

Available Rake tasks are:

rake build            # Build rcmd-1.6.4.gem into the pkg directory
rake clean            # Remove any temporary products
rake clobber          # Remove any generated files
rake clobber_rdoc     # Remove RDoc HTML files
rake console          # Open an IRB console with this gem loaded
rake install          # Build and install rcmd-1.6.4.gem into system gems
rake install:local    # Build and install rcmd-1.6.4.gem into system gems without network access
rake rdoc             # Build RDoc HTML files
rake reinstall        # Remove, build, and install gem
rake release[remote]  # Create tag v1.6.4 and build and push rcmd-1.6.4.gem to Rubygems
rake rerdoc           # Rebuild RDoc HTML files
rake test:all         # Run all RSpec tests
rake test:db          # Test Database functionality (sqlite3 required)
rake test:mainlib     # Test main rcmd lib