lilydjwg/pssh

Allow host wildcard

cacharle opened this issue · 9 comments

cacharle commented

It would be nice if pssh could read my ssh config and allow me to pick hosts based on a wildcard.

e.g

$ cat ~/.ssh/config
Host hello-foo
    ...
Host hello-bar
    ...

and we run: $ pssh -H 'hello-*' echo bye to execute the command on hello-foo and hello-bar

I am willing to contribute this feature if it's not available yet.

lilydjwg commented

What if the string after Host already contains a wildcard?

cacharle commented

I guess we just ignore Host containing wild cards?

lilydjwg commented

That means when the user optimizes their ssh config, they may silently break existing pssh commands / scripts. It doesn't sound great.

Also, you can just grep out your hosts. Perhaps a way to generate a host list dynamically is better?

cacharle commented

Indeed, you can do create a simple script to grep the hosts.

I just think that it's something that is convenient and I don't think every person that uses this project should have to make their own script for this.

If you're scared of breaking existing scripts, we can just create a new option like --host-regex.

lilydjwg commented

I mean the Host line is not a host list, but host patterns. Giving one thing two roles isn't a good idea.

Btw, I wonder why does one have a lot of non-wildcard Host lines, but still want to run the same command on them?

cacharle commented

Lots of device with a static IP and not human friendly domain names.

lilydjwg commented

/etc/hosts seems to be a better place? Except that it needs root.

cacharle commented

ye, but then if I want to run something on 10 devices, I need to list them one by one, which is painful:

pssh -H "location-1-device-1 location-1-device-2 location-1-device-3 location-1-device-4 location-1-device-5 location-1-device-6 location-1-device-7 location-1-device-8 location-1-device-9" echo smth

I'd like to be able to do: pssh -H 'location-1-device-*' echo smth or pssh -H 'location-*-device-*'

I guess I'll write a script for that..

cacharle commented

For posterity, here is what I came up with:

#!/bin/sh

set -e

host_regex="$1"
shift
host_tmp_file=$(mktemp)

echo 'Running on hosts:'
grep '^Host ' ~/.ssh/config |
    grep -v '\*' |
    cut -d ' ' -f 2 |
    grep -E "$host_regex" |
    tee "$host_tmp_file"
echo '----------------'

pssh -h "$host_tmp_file" "$@"

Usage: ./pssh-regex 'location-.*-device-.*' -i -p 10 echo hello