Linode StackScript Builder

MonitoringLinode

Build StackScript configurations with user-defined fields, compatible images, and bash provisioning scripts.

Last verified: May 2026

Linode StackScripts Configuration

Build StackScript configurations with user-defined fields (UDFs), compatible images, bash provisioning scripts, and deployment automation.

Required Fields

labelimagesscript

{
  "label": "web-server-setup",
  "description": "Provision a production-ready web server with Nginx, Node.js, and security hardening",
  "images": ["linode/ubuntu24.04", "linode/ubuntu22.04", "linode/debian12"],
  "isPublic": false,
  "revNote": "v2.1 — Added fail2ban and automatic security updates",
  "userDefinedFields": [
    {
      "name": "hostname",
      "label": "Server Hostname",
      "type": "text",
      "required": true,
      "example": "web-01"
    },
    {
      "name": "app_port",
      "label": "Application Port",
      "type": "text",
      "default": "3000",
      "required": false
    },
    {
      "name": "enable_firewall",
      "label": "Enable UFW Firewall",
      "type": "oneOf",
      "options": ["yes", "no"],
      "default": "yes"
    },
    {
      "name": "ssh_pubkey",
      "label": "SSH Public Key",
      "type": "text",
      "required": true
    }
  ],
  "script": "#!/bin/bash\n# <UDF name=\"hostname\" label=\"Server Hostname\" />\n# <UDF name=\"app_port\" label=\"Application Port\" default=\"3000\" />\n# <UDF name=\"enable_firewall\" label=\"Enable UFW\" oneOf=\"yes,no\" default=\"yes\" />\n# <UDF name=\"ssh_pubkey\" label=\"SSH Public Key\" />\n\nset -euo pipefail\nhostnamectl set-hostname $HOSTNAME\napt-get update && apt-get upgrade -y\napt-get install -y nginx nodejs npm fail2ban ufw\n\nif [ \"$ENABLE_FIREWALL\" = \"yes\" ]; then\n  ufw default deny incoming\n  ufw default allow outgoing\n  ufw allow ssh\n  ufw allow http\n  ufw allow https\n  ufw --force enable\nfi\n\necho \"$SSH_PUBKEY\" >> /root/.ssh/authorized_keys\nsystemctl enable nginx\necho \"StackScript complete\"\n"
}

Generated Output

Output will appear here...

How It Helps

Linode StackScripts are reusable bash provisioning scripts that run on first boot — bringing a fresh Linode from a clean OS image to a configured application server in one step. The Linode StackScript Builder generates StackScript configurations including user-defined fields (UDFs), compatible image whitelists, and the provisioning bash with safety patterns (idempotency, error handling). Output is ready to register via the Linode API.

Things Engineers Ask

What runs the StackScript — and as which user?

StackScripts run as root during the Linode's first boot, before login is available. You can use this to install packages, configure system services, and create users. The script runs once per Linode (StackScript variables track the run). For idempotency on rebuilds, design the script so re-running is a no-op.

How do UDFs work?

User-Defined Fields are declared in the StackScript metadata and prompt the operator (or API caller) for values at Linode creation time. UDF values appear as environment variables inside the StackScript. They're how you make one StackScript reusable across slight variations — 'install nginx for [DOMAIN]' rather than hardcoding the domain.

In Practice

Your team has been spinning up fresh Linodes by SSH'ing in and running a 200-line bootstrap script that lives in someone's home directory. After three engineers leaving and three slightly-different bootstrap variants, you formalize the process into a StackScript with the builder. New Linodes are now provisioned via Terraform with a StackScript reference and UDFs for environment-specific values. Total drift between Linodes goes from 'whatever the bootstrap looked like that week' to zero.

Practical Applications

1Building a standardized 'web server' StackScript that installs nginx, configures TLS via Let's Encrypt, and sets up a baseline firewall.
2Creating a StackScript that takes UDFs (domain name, deploy user, repo URL) and customizes the provisioning to those inputs without editing the script for each Linode.
3Generating a StackScript that pulls application code from a git repo and runs the application-specific bootstrap (npm install, systemd unit registration, environment file rendering).
4Migrating one-off shell scripts engineers have been pasting into fresh Linodes into proper StackScripts with version control and consistent execution.

Behind the Scenes

The builder collects StackScript label, description, UDF declarations (name, label, default, required), compatible images list, and the bash provisioning. It validates the UDF syntax against Linode's expected metadata format and emits an API-ready JSON payload plus the StackScript body. The bash is checked for common safety patterns (set -e, error handling) and warnings are surfaced where they're missing.

Things the Docs Don’t Tell You

TIP

Always `set -e` and `set -o pipefail` in StackScripts. Without them, a failed step silently succeeds and you end up with a half-configured Linode that 'looks fine' but doesn't actually work.

TIP

Use UDFs for everything that would otherwise hardcode the script to a specific environment. A StackScript that takes domain, email, deploy user, and git URL as UDFs is reusable; one with those hardcoded is one-off.

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