Execute remote command (SSH)

🟡 Intermediate

script

This example shows how to run commands on a remote host from an OnSphere script using SSH with PEM-format key authentication.

Create a detached script scheduled to run every 30 seconds.
Write a JavaScript script that opens an SSH connection and executes a command on the remote host.
Generate an RSA key pair in PEM format and register both files as module resources.
Deploy the public key to the remote host’s authorized_keys file to enable key-based authentication.

git checkout origin/osp-scripts-configuration .
git checkout origin/example-scripts-execute-remote-command .

Configuration

Steps

1. Create a detached script

root/script/detached.scripts

The detached script has the task to execute the script every 30 seconds.

{
    "moduleId" : "modules.scripts.scripts-1",
    "sourceFile" : "root/script/script.js",
    "accessedValues" : [],
    "scheduledExecutions" : ["0/10 * * ? * * *"]
}

1. Create a script to execute on a remote target (via SSH)

root/script/script.js

Note

Change the IP/hostname and check if the SSH is enabled on your test target.

main();

function main() {
    
    log.info("Execute example script with schedule execution and certificate authentification");
    // Create the runner for SSH with CERTIFICATE
    let runner = ssh.certCmdBuilder("10.100.0.77", 51234, "osp", "test")
    // Set the maximum time to establish the connection (keep it low)
    .setConnectionTimeout(5)
    // Set a maximum time after witch the SSH drop the line.
    .setMaxCommandTime(5)
    .build();

    // Establish a SSH connexion and run a command.
    let res = runner.run(["echo \"executed\"", ">", "/tmp/script-execution-result"]);

    // If SSH failure
    if (res.exceptionCode !== 0) 
    {
        log.error("Fail to establish the SSH connection with error code [" + res.exceptionCode + "]");    
        return;
    }

    if (res.returnCode !== 0) 
    {
        log.error("Fail to execute the command error code [" + res.exceptionCode + "] and stdin [" + res.stdIn + "] and stderr [" + res.stdErr +"]" );    
        return;
    }
    
    log.info("Execution success output is [" + res.stdIn + "]");
}

3. Add the SSH certificates as resource

Note

The certificate must be generated in PEM format. The OPENSSH format is not supported by the lib used to establish the SSH connection. You can for example use ssh-keygen -t rsa -m PEM

modules/script/scripts-1/module.resources

{
    "resources": [
        {
            "source": "root/ssh/",
            "destination": "certs"
        }
    ]
}

root/ssh/test

root/ssh/test.pub

ssh-rsa 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 manticore@manticore

1. Deploy the SSH key on host

To authenticate with SSH key the host must have the public key listed inside its ~/.ssh/authorized_keys file. Use one of the following method :

use ssh-copy-id from a linux host

ssh-copy-id -i [] user@host

write the public key inside the file

cat [pubkey.pem] >> ~/.ssh/authorized_keys