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šŸ‘Øā€šŸ­ Welder

Welder allows you to set up a Linux server with plain shell scripts.

I wrote it out of frustration with Ansible. Ansible is an amazing and powerful tool, but for my needs it's just too much. 90% of the time all I need is to be able to run a shell script on the server, without extra dependencies.

In most basic terms, that's what welder does.

But there's some more.

āš ļø NOTE: if you're looking for the previous version of welder, you'll find it here.

Features

Directory structure

An example directory structure:

ā”œā”€ā”€ playbook.conf
ā”œā”€ā”€ config.conf
ā”œā”€ā”€ firewall
ā”‚Ā Ā  ā”œā”€ā”€ files
ā”‚Ā Ā  ā”‚Ā Ā  ā””ā”€ā”€ rules.v4
ā”‚Ā Ā  ā””ā”€ā”€ firewall.sh
ā”œā”€ā”€ nginx
ā”‚Ā Ā  ā””ā”€ā”€ nginx.sh
ā”œā”€ā”€ system
ā”‚Ā Ā  ā”œā”€ā”€ files
ā”‚Ā Ā  ā”‚Ā Ā  ā”œā”€ā”€ 10periodic
ā”‚Ā Ā  ā”‚Ā Ā  ā”œā”€ā”€ 50unattended-upgrades
ā”‚Ā Ā  ā”‚Ā Ā  ā””ā”€ā”€ ssh_key
ā”‚Ā Ā  ā””ā”€ā”€ system.sh
ā””ā”€ā”€ website
    ā”œā”€ā”€ files
    ā”‚Ā Ā  ā””ā”€ā”€ site.conf.template
    ā””ā”€ā”€ website.sh

Playbook

Playbook is just a list of modules to execute. Example:

# playbook.conf

system
firewall
nginx
website

Config

Config file:

SITE_DOMAIN = "example.com"
SITE_DIR = "/var/www"

You can reference config variables in your scripts like this:

#!/bin/sh
set -xeu

. ./config.conf

echo $SITE_DOMAIN

Templates

Welder offers simple sed-based templates that interpolate variables in double brackets with values defined in config.

# website/files/nginx-site.conf.template

server {
    listen 80;

    server_name {{ SITE_DOMAIN }};
    root {{ SITE_DIR }}/current/public;
}

Usage

Run the playbook with the following command:

welder run playbook.conf user@example.com

How it works

Welder goes through the modules defined in playbook.conf, copies them to a cache directory, compiles config files and templates, rsyncs the directory to the server. Then it runs the setup script that invokes all *.sh files within the playbook (all scripts will be called with sudo).

Example setup script

# nginx/nginx.sh

# NOTE: sudo isn't necessary because the whole script will be
#       invoked as `sudo nginx/nginx.sh`

set -xeu # 'u' will give you warnings on unbound config variables

add-apt-repository -y ppa:nginx/stable
sapt-get update && apt-get install -y nginx

service nginx start

cp files/nginx.conf /etc/nginx/nginx.conf

# Disable default site
if [ -f /etc/nginx/sites-enabled/default ]; then
  rm /etc/nginx/sites-enabled/default
fi

service nginx restart

Installation

The only dependency required by welder is rsync (which should be pre-installed on your system in most cases).

  1. Check out welder into ~/.welder (or whatever location you prefer):

    $ git clone https://github.com/pch/welder.git ~/.welder
    
  2. Add ~/.welder/bin to your $PATH for access to the welder command-line utility.

    $ echo 'export PATH="$PATH:$HOME/.welder/bin"' >> ~/.bash_profile
    

    Ubuntu Desktop note: Modify your ~/.bashrc instead of ~/.bash_profile.

    Zsh note: Modify your ~/.zshrc file instead of ~/.bash_profile.

  3. Restart your shell so that PATH changes take effect. (Opening a new terminal tab will usually do it.) Now check if welder was set up:

    $  which welder
    /Users/my-user/Code/welder/bin/welder
    

Caveats

Since welder allows you to run anything on the server, you should use it with caution. It won't protect you from screw-ups, like rm -rf "/$undefined_variable".

Use at your own risk.

Alternatives

There's an alternative version of welder (the classic version), re-implemented in Python by @thomas-mc-work.