JCore Script Tools

Helpers for common scripting tasks like modifying configuration files

Installation

pnpm install --save @jcoreio/script-tools

or

yarn add @jcoreio/script-tools

Standalone Functions

####exec

Promisified version of child_process.exec that also prints the command being called and and includes the original command in any error message

const { exec } = require('@jcoreio/script-tools')

const stdout = (await exec('git pull')).stdout

####execRemote

Executes a command on a remote host via SSH. Disables SSH host key checking by default. To re-enable SSH host key checking, pass strictHostKeyChecking: true.

Options:

• host: string, required: remote hostname
• user: string, optional: username for remote login
• keyFile: string, optional: location of the SSH key pair to access the remote host
• command: string, required: command to run on the remote host
• prefix: string, optional: optionally prefix piped output with the specified value. Disabled by default.
• spawnOpts:
  • sudo: boolean, optional: true if the ssh command should be run with sudo. Defaults to false.
  • captureStdio: boolean, optional: true if the process's stdio should be captured for later use as well as being piped through to the parent process. Defaults to false.

const { execRemote } = require('@jcoreio/script-tools')

await execRemote({
  host: 'remotehost.com',
  user: 'ubuntu',
  keyFile: '~/key.pem',
  command: 'sudo reboot',
  spawnOpts: {
    captureStdio: true,
  },
})

####lineInFile

Ensures that a line exists in a file. Optionally replaces a line matching a specified pattern.

Options:

• file: string, required: path of the destination file
• line: string, required: line to add or replace
• replace: string, optional: pattern of line to replace
• insertAfter: string, optional: insert the line after the specified line
• newLineAtEnd: boolean, optional: true if the file should have a newline at the end. Defaults to true.
• sudo: boolean, optional: true if sudo should be used when writing the file. Defaults to false.
• mode: string, optional: file permissions to set, e.g. '775'
• owner: string, optional: file owner to set
• group: string, optional: file group to set

const { lineInFile } = require('@jcoreio/script-tools')

await lineInFile({
  file: '/etc/myPackage.conf',
  line: 'maxWorkers = 2',
  replace: 'maxWorkers',
  sudo: true,
  owner: 'root',
  group: 'root',
})

####spawn

Promisified version of child_process.spawn that also prints the command being called and pipes stdio to the parent process by default

Arguments:

• command: string, required: command to run
• arguments: Array, optional: arguments
• options: Object, optional:
  • sudo: boolean, optional: true if the ssh command should be run with sudo. Defaults to false.
  • prefix: string, optional: optional prefix to prepend to each line of stderr / stdout from the child process
  • captureStdio: boolean, optional: true if the process's stdio should be captured for later use as well as being piped through to the parent process. Defaults to false.

const { spawn } = require('@jcoreio/script-tools')

await spawn('git', ['clone', 'https://github.com/myorg/myrepo'], {
  captureStdio: true,
})

####writeFile

Writes a file if its contents do not already match, and optionally sets the file's permissions

Arguments:

• file: string, required: file path to write
• contents: string, required: file contents to write
• options: Object, optional:
  • sudo: boolean, optional: true if sudo should be used when writing the file. Defaults to false.
  • mode: string, optional: file permissions to set, e.g. '775'
  • owner: string, optional: file owner to set
  • group: string, optional: file group to set

const { writeFile } = require('@jcoreio/script-tools')

await writeFile('.gitignore', 'node_modules', {
  mode: '775',
  owner: 'root',
  group: 'root',
})

ProcessHandler class

Ensures that child processes are terminated when the parent process exits

Constructor options:

• maxProcesses: number, optional: the maximum number of simultaneous running processes. Defaults to 100. If this limit is exceeded, an Error will be thrown when the next process is added.

const { ProcessHandler } = require('@jcoreio/script-tools')

const handler = new ProcessHandler({ maxProcesses: 10 })

await handler.exec('docker kill my-container')

await handler.spawn('git', ['pull'])

await handler.execRemote({
  host: 'myhost.mycompany.com',
  command: 'uptime',
})

const child = require('child_process').spawn('ls', ['-l'])
handler.killOnExit(child)

handler.killAll()

The following methods work the same as their standaline counterparts, and also return a process that will be terminated when the parent process exits:

• exec
• execRemote
• spawn

#####killOnExit

Monitors an already-launched process and kills it when the parent process exits

Arguments:

• process: ChildProcess, required: process to kill when the parent process exits

#####killAll

Kills all processes that are being monitored. This action is run automatically when node is about to exit.

License

Apache-2.0