looking for a starting point for a web app to run a script locally (on server)

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Talkiet

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#261441 27-Nov-2019 21:42

I am competent at several things, website development is NOT one of those things and google is throwing up a LOT of results and I don't even know enough about how to intelligently narrow the search...

I am trying to find a way to create a webpage on a linux machine that reads a file of several remote machines that are either online, or not - and presents through the browser a list of these, coded (by colour/icon) to show whether each is currently online or offline (That's easy enough for me to create a CSV or even HTML I guess with a cron job or something)... The major bit I am wondering where to start is that each line should have a few buttons beside it and each button should kick off a command on the webserver. (In this case the command/script will be to remotely execute a job on the remote machine through SSH)...

All the "hard" work of the underlying capability is done - this is about the presentation so someone doesn't need to log into a machine and remember/enter CLI commands to kick off the commands.

I've heard people say "just use php or cgi" but that's a bit generic for me at the moment.

Server is Apache, I have full control of it.

Any starting point (ideally an example of how to click on an icon on a web page and execute a command on a server) would be greatly appreciated.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

marpada

476 posts

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#2361869 27-Nov-2019 22:18

It's easy enough to do it from scratch using any programming language, but I'd recommend you to use any existing tool for managing remote servers like RunDeck or Ansible Tower/AWX.

itxtme

2102 posts

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#2361879 28-Nov-2019 00:09

When you say "click on an icon on a web page and execute a command" what method of communication are you referring to? I get that you want to run the webpage locally but how do you plan on executing the command remotely? Are you having HTTP servers on the remote computers too or are you planning on SSH'ng in from the local webpage?

michaelmurfy

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#2361885 28-Nov-2019 06:23

You can essentially use anything. Python3 + Flask or NodeJS come to mind here.

Just use Apache mod_proxy to proxy through to the web app.

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Talkiet

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#2362027 28-Nov-2019 09:10

itxtme:

When you say "click on an icon on a web page and execute a command" what method of communication are you referring to? I get that you want to run the webpage locally but how do you plan on executing the command remotely? Are you having HTTP servers on the remote computers too or are you planning on SSH'ng in from the local webpage?

By having the webserver run a remote bash script via SSH on the target machine...

The only thing exposed on the remote machines is SSH, and that is only exposed via an openvpn tunnel back to the main machine. They are not open to the real world at all for inbound connections.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

chevrolux

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#2362078 28-Nov-2019 09:38

Noob PHP guy here....

So I would say, the 'buttons' on your page (oh and use Bootstrap CSS to make everything look nice) are just hyperlinks to the appropriate PHP script that triggers the shell script. I would guess the same script is used for all the servers, just with different variables?

The URL of the buttons would be, for example, 'https://talkiet.co.nz/shell_script.php?server=host1&action=reboot'

Then in 'shell_script.php', you can can just pull out that info from the $_GET variable by referencing whatever key you used in the URL.... $_GET['server'] or $_GET['action']

Finally to trigger the shell script... there is the php command 'exec()' or 'shell_exec()' which runs commands on the system... I've used exec() successfully, not sure of the benefits of exec vs shell_exec.

Lastly, just stick "header('Location: /home');"... substituting your index page of course for location, so the php script take you back to the main page after running. Good thing about exec is that's it's non-blocking so you don't need to wait for it to run.

Edit: I guess there are security concerns running shell scripts from web pages, but I assumed you already realise that and the page won't be publicly accessible.

Talkiet

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#2362112 28-Nov-2019 09:51

chevrolux:

Noob PHP guy here....

So I would say, the 'buttons' on your page (oh and use Bootstrap CSS to make everything look nice) are just hyperlinks to the appropriate PHP script that triggers the shell script. I would guess the same script is used for all the servers, just with different variables?

The URL of the buttons would be, for example, 'https://talkiet.co.nz/shell_script.php?server=host1&action=reboot'

Then in 'shell_script.php', you can can just pull out that info from the $_GET variable by referencing whatever key you used in the URL.... $_GET['server'] or $_GET['action']

Finally to trigger the shell script... there is the php command 'exec()' or 'shell_exec()' which runs commands on the system... I've used exec() successfully, not sure of the benefits of exec vs shell_exec.

Lastly, just stick "header('Location: /home');"... substituting your index page of course for location, so the php script take you back to the main page after running. Good thing about exec is that's it's non-blocking so you don't need to wait for it to run.

Edit: I guess there are security concerns running shell scripts from web pages, but I assumed you already realise that and the page won't be publicly accessible.

Many thanks! That post has given me a good starting point to look at. And yeah - there are no real security concerns. The system is closed off and only available on LAN. The server and all remote clients are on VPN.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

hio77

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#2362410 28-Nov-2019 20:05

michaelmurfy: You can essentially use anything. Python3 + Flask or NodeJS come to mind here.

Just use Apache mod_proxy to proxy through to the web app.

/shudders now your talking like our bot teams!

few options here, will reach out to ya neil :)

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Hibino

166 posts

Master Geek

#2363387 30-Nov-2019 11:54

You can have 3 php files to do it. The exec() function in php can catch reply from the command it runs, so you can use the output of your script to make it extendable.

since all calls are ssh so you will need to have private/public key auth, you won't be able to enter password for ssh in exec().

a config php file, contains ip address of servers and commands so you can easily change later

//ssh username
$username = 'abcd';

// script to check server status, the script can output a digit for different status
$status_cmd = '/a/b/c/s.sh';
// colors for the output of server status script
$status_color = array(
'' => '#000000', // error connect or nothing from the script
'1' => '#ff0000',
'2' => '#00ff00',
'3' => '#0000ff',
);

// list of servers
$servers = array(
'name_1' => '1.1.1.1',
'name_2' => '2.2.2.2',
'name_3' => '3.3.3.3',
);

// commands for each server
$cmds = array(
'btn_1' => '/a/b/c/d/a.sh',
'btn_2' => '/a/b/c/d/b.sh',
'btn_3' => '/a/b/c/d/c.sh',
);

a server list php file, loop through the server and commands display on page

require_once( 'config.php' );

// get all status, you can use ajax calls so it won't block page displaying, but it is LAN so this should be fast enough
$server_status = array();
foreach( $servers as $s_name => $ip ){
    $output = array();
    exec( "ssh {$username}@{$ip} {$status_cmd}", $output );
    $server_status[$s_name] = !empty( $output ) ? $output[0] : '';
}

// display a table of all servers
echo '<table width="100%">';
foreach( $servers as $s_name => $ip ){
    echo '<tr>',
         '<td>', $s_name, '</td>',
         '<td>', $ip, '</td>'.
         '<td bgcolor="' ,$status_color[$server_status[$s_name]], '"> </td>',
         '<td>';
    foreach( $cmds as $btn_name => $cmd ){
        // commands are run in new window/tab, you can use ajax or iframe to have result in same page
        echo '<a href="run.php?server=' .$s_name. '&btn=' .$btn_name. '" target="blank"></a>, ';
    }
    echo '</td>',
         '</tr>';
}
echo '</table>';

a php to run the command from button press

require_once( 'config.php' );

$s_name = $_GET['s_name'];
$btn_name = $_GET['btn_name'];
$output = array();
exec( "ssh {$username}@{$servers[$s_name]} {$cmds[$btn_name]}", $output );
if( !empty( $output ) ){
echo( implode( '<br>', $output ) );
}else{
echo 'error with command';
}