rex

README

rex (remote execute)

rex executes given command(s) on multiple remote hosts, ssh-connecting to them in parallel.

You're expected to have passwordless access to hosts, rex authenticates itself with the help of ssh-agent that is expected to be running.

Setup

go install github.com/artyom/rex@latest

Binary will be placed either to directory set with ${GOBIN} environment or to ${GOPATH}/bin which defaults to ${HOME}/go/bin.

Usage examples

Execute uptime command on multiple hosts:

rex -l root -cmd 'uptime' host1.example.com host2.example.com

Default username may be overridden on a per-host basis:

rex -l root -cmd 'uptime' host1.example.com admin@host2.example.com

Default username can be set as environment variable:

export REX_USER=admin

If output should be saved to files, not printed to console, use -logs flag:

rex -logs -l root -cmd '/etc/init.d/mysql restart' db1.example.com db2.example.com

By default output would be saved to /tmp/db1.example.com.stdout, /tmp/db1.example.com.stderr, etc. Empty files would be automatically removed. Override filename templates with -logs.stderr and -logs.stdout flags.

When complex processing is required on remote hosts, it can be easier to write separate script and pass it via -stdin flag:

rex -stdin my-script.sh -cmd '/bin/sh' host1.example.com host2.example.com

Note, -stdin argument should be a regular file, since it is read multiple times — one time per remote host, so giving something pipe-like here won't work.

The same mechanism can be used to copy arbitrary data:

rex -stdin archive.tar.gz -cmd 'tar xz -C /tmp && cp -v /tmp/file-from-archive /dst' host1 host2

Since in most workflows multiple hosts are used together over and over again, it's easier to group them together. rex treats hostname starting with @ symbol as group name; groups are read from yaml file specified by -g flag which defaults to $HOME/.rex-groups.yaml. Consider the file with following content:

alpha:
  - alpha1.example.com
  - alpha2.example.com
  - alpha3.example.com
beta:
  - beta1.example.com
  - beta2.example.com
  - beta3.example.com
  - beta4.example.com

Now rex can use groups:

rex -cmd 'uptime' @alpha @beta

Both groups and arbitrary hosts can be used together.

License

MIT

Documentation

Overview

Command rex executes given command on multiple remote hosts, connecting to them via ssh in parallel.

You're expected to have passwordless acces to hosts, rex authenticates itself speaking to ssh-agent that is expected to be running.