Support running commands on remote servers over SSH

[danielbachhuber]

As a WP-CLI user, it would be convenient if I could use a global --ssh=<host> argument to run a command against a WordPress install on a remote server:

$ wp --ssh=v:/srv/www/wordpress-develop.dev/src option get home
http://wordpress-develop.dev

To modify the behavior of the command at runtime, it should be possible to hook in a custom command:

WP_CLI::add_hook( 'before_ssh', function() {
    switch( WP_CLI\Utils\parse_ssh_url( WP_CLI::get_runner()->config['ssh'], PHP_URL_HOST ) ) {
        case 'runcommand.io':
            putenv( 'WP_CLI_SSH_PRE_CMD=export PATH=$HOME/bin:$PATH' );
            break;
    }
});

https://github.com/xwp/wp-cli-ssh is good prior art from @westonruter and @jonathanbardo that we can crib from.

[danielbachhuber]

@westonruter @jonathanbardo Do you recall why you originally used passthru() instead of ssh2_connect() and its corresponding library?

[westonruter]

@danielbachhuber not exactly, but two reasons come to mind:

1. I wasn't aware of ssh2_connect().
2. And ssh2_connect() isn't a core PHP function but part of a PECL extension.

[jonathanbardo]

I think at the time we also needed to be able to ssh into a jump server before reaching the final web server. This was going to be easier to do using passthru().

[danielbachhuber]

Thanks guys. I think I'll end up going with passthru() because it will be easier to reuse the user's SSH config details.

[danielbachhuber]

Debating whether we need to support port in some fashion. I'm inclined to have users define the port in their SSH config if it's non-standard.

[danielbachhuber]

@westonruter @jonathanbardo Would you mind testing out the current implementation when you have a moment, and let me know what you think? Specifically, I'm looking for feedback on the implementation, and any additional features you think it needs.

[jonathanbardo]

@danielbachhuber I agree, SSH config for non standard port number makes sense.

[westonruter]

Would you mind testing out the current implementation when you have a moment, and let me know what you think? Specifically, I'm looking for feedback on the implementation, and any additional features you think it needs.

@timneutkens actually, since you've been using WP-CLI SSH most frequently of late (AFAIK), would you give this PR a try and provide feedback?

[danielbachhuber]

would you give this PR a try and provide feedback?

Just to clarify, the code has already landed on master. If you're using the Phar install, you can wp cli update --nightly to try it out.

[timneutkens]

@westonruter @danielbachhuber Will do. Bet I will have time to review this tomorrow.

[timneutkens]

Hey @danielbachhuber, looks good :)

Only thing I noticed is that wp is hardcoded here: https://github.com/wp-cli/wp-cli/blob/master/php/WP_CLI/Runner.php#L356.

Few weeks ago I created a pull request on wp-cli-ssh (xwp/wp-cli-ssh#27) to add support for a custom command to be ran. So you could do something like: wpcli_command: php ./vendor/bin/wp (https://github.com/xwp/wp-cli-ssh/blob/master/wp-cli.sample.yml#L22) when you install wp-cli using composer.

The hook you implemented probably solves the issue I had wanting to use a different php command for wp-cli. Just not the part where you would want to use a different path to the command.

[danielbachhuber]

Only thing I noticed is that wp is hardcoded here

That was intentional, although I could be convinced otherwise.

The hook you implemented probably solves the issue I had wanting to use a different php command for wp-cli. Just not the part where you would want to use a different path to the command.

Well, my thinking is that you could create a just-in-time alias to a different path, if WP-CLI wasn't available as wp. Even though there is a workaround, it's somewhat intentional not to permit an arbitrary executable (e.g. it's a design decision that --ssh should only be used to execute WP-CLI).

What do you think about my explanation?

[timneutkens]

That's a fair point. You could alias wp using the hook. So that will do.

[timneutkens]

I also noticed that you can provide WP_CLI_PHP to use another version php. So that is an even better solution to the issue I had 😄

[danielbachhuber]

Debating whether we need to support port in some fashion. I'm inclined to have users define the port in their SSH config if it's non-standard.

I figured out a syntax for us to support port:

192.168.50.10:2222:/srv/www/wordpress-develop.dev/src

If the port isn't specified, then 22 is assumed:

192.168.50.10:/srv/www/wordpress-develop.dev/src

[timneutkens]

I agree, that's the best syntax for supporting ports 👍

[scribu]

Git uses a syntax without a colon between port and path:

ssh://[user@]host.xz[:port]/path/to/repo.git/

https://git-scm.com/docs/git-clone

[scribu]

Since it's a standard URL format, it should be parseable with PHP's parse_url().

[danielbachhuber]

Since it's a standard URL format, it should be parseable with PHP's parse_url().

I agree, I'll update.

[danielbachhuber]

Actually, parse_url() isn't quite compatible with using a SSH config like v. If we use regex instead, we could support a similar syntax to standard URL format:

@prod:
  ssh: rc~/webapps/production
@dev:
  ssh: v/srv/www/runcommand.dev
@wpdev:
  ssh: v:2222/srv/www/wordpress-develop.dev/src

[danielbachhuber]

Feeling pretty good with this now as a v1. I'll handle website documentation as a part of #2767

[timneutkens]

Thanks Daniel, will have to make so changes to our internal setup 👍

[toleabivol]

How would I do it if I usually login with :
ssh -i ~/.ssh/pemfiles/yyyy.pem [email protected]

[danielbachhuber]

@toleabivol You'll need to set a SSH config with the identity file reference.