Setup a Docker Swarm cluster

.gitignore

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+*.log
+nodes.rb
+.settings.yml
+.swarm
+.vagrant

LICENSE

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+Copyright (C) 2023 by Kris Lamoureux <kris@lamoureux.io>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+PERFORMANCE OF THIS SOFTWARE.

Makefile

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+.PHONY: all vagrant clean
+
+all: vagrant
+
+vagrant:
+	vagrant up --no-destroy-on-error --no-color | tee ./vagrantup.log
+
+clean:
+	vagrant destroy -f --no-color
+	rm -rf .vagrant vagrantup.log .swarm

README.md

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+# Vagrant Docker Swarm Environment
+
+**Warning: For development only, do not use for production**
+
+This repository contains a Vagrantfile and the necessary configuration files
+for automating the setup of a Docker Swarm cluster using Vagrant’s shell
+provisioning. You can easily override the default settings for the Vagrant
+environment and the Swarm cluster to suit your needs. Customize global
+settings via the `.settings.yml` file, and specify per-node overrides using the
+`NODES` Ruby hash in `nodes.rb`.
+
+By default, `make` will create three Debian Stable x86_64 Docker Swarm nodes.
+Each node will have:
+- 2 threads/cores (depending on architecture)
+- 2 GB of RAM
+- ~1 GB of storage
+
+**Warning: Make sure your machine has enough resources or adjust override settings.**
+
+# Quick Start
+Get your Vagrant Docker Swarm cluster up and running with these simple steps:
+
+- Setup the Cluster
+
+  Run the following command to clean any previous setup and start fresh:
+  ```bash
+  make clean && make
+  ```
+
+- SSH into a Node
+
+  Access the first node (`node1`) in your cluster:
+  ```bash
+  vagrant ssh node1
+  ```
+
+- Verify Cluster Setup
+
+  List all the nodes to ensure they've joined the cluster successfully:
+  ```bash
+  docker node ls
+  ```
+
+
+# Global Overrides
+If you wish to override the default settings on a global level,
+you can do so by creating a `.settings.yml` file based on the provided
+`example-.settings.yml` file:
+
+```bash
+cp example-.settings.yml .settings.yml
+```
+
+Once you have copied the `example-.settings.yml` to `.settings.yml`, you can
+edit it to override the default settings. Below are the available settings:
+
+## Vagrant Settings Overrides
+- `VAGRANT_BOX`
+  - Default: `debian/bookworm64`
+  - Tested most around Debian Stable x86_64 (currently Bookworm)
+- `VAGRANT_CPU`
+  - Default: `2`
+  - Two threads or cores per node, depending on CPU architecture
+- `VAGRANT_MEM`
+  - Default: `2048`
+  - Two GB of RAM per node
+- `SSH_FORWARD`
+  - Default: `false`
+  - Enable this if you need to forward SSH agents to the Vagrant machine(s)
+
+## Docker Swarm Settings Overrides
+- `SWARM_NODES`
+  - Default: `3`
+  - The total number of nodes in your Docker Swarm cluster
+- `JOIN_TIMEOUT`
+  - Default: `60`
+  - Timeout in seconds for nodes to obtain a swarm join token
+
+# Per-Node Overrides
+The naming convention for nodes follows a specific pattern: `nodeX`, where `X`
+is a number corresponding to the node's position within the cluster. This
+convention is strictly adhered to due to the iteration logic within the
+`Vagrantfile`, which utilizes a loop iterating over an array range defined by
+the number of swarm nodes (`Array(1..SWARM_NODES)`). Each iteration of the loop
+corresponds to a node, and the loop counter is in the node name (`nodeX`).
+
+The overrides, if specified in `nodes.rb`, take the highest precedence,
+followed by the overrides in `.settings.yml`, and lastly, the defaults hard
+coded in the `Vagrantfile` itself. This hierarchy allows for a flexible
+configuration where global overrides can be specified in `.settings.yml`, and
+more granular, per-node overrides can be defined in `nodes.rb`. If a particular
+setting is not overridden in either `.settings.yml` or `nodes.rb`, the default
+value from the `Vagrantfile` is used.
+
+If you wish to override the default settings on a per-node level, you can do so
+by creating a `nodes.rb` file based on the provided `example-nodes.rb` file:
+
+```bash
+cp example-nodes.rb nodes.rb
+```
+
+Once you have copied the `example-nodes.rb` to `nodes.rb`, you can edit it to
+override the default settings. Below are the available settings available
+per-node:
+
+- `BOX`
+  - Default: `debian/bookworm64` (or as overridden in `.settings.yml`)
+  - Vagrant box or image to be used for the node.
+- `CPU`
+  - Default: `2` (or as overridden in `.settings.yml`)
+  - Defines the number of CPU cores or threads (depending on architecture).
+- `MEM`
+  - Default: `2048` (2 GB) (or as overridden in `.settings.yml`)
+  - Specifies the amount of memory (in MB) allocated to the node.
+- `SSH`
+  - Default: `false` (or as overridden in `.settings.yml`)
+  - Enable this if you need to forward SSH agents to the Vagrant machine
+
+All settings are optional, and as many or as few options can be overridden on
+any arbitrary node.

Vagrantfile

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+# -*- mode: ruby -*-
+# vi: set ft=ruby :
+
+# Load override settings
+require 'yaml'
+settings_path = '.settings.yml'
+settings = {}
+
+if File.exist?(settings_path)
+  settings = YAML.load_file(settings_path)
+end
+
+# Default Vagrant settings
+VAGRANT_BOX = settings['VAGRANT_BOX'] || 'debian/bookworm64'
+VAGRANT_CPU = settings['VAGRANT_CPU'] || 2
+VAGRANT_MEM = settings['VAGRANT_MEM'] || 2048
+SSH_FORWARD = settings['SSH_FORWARD'] || false
+
+# Default Swarm settings
+SWARM_NODES  = settings['SWARM_NODES']  || 3
+JOIN_TIMEOUT = settings['JOIN_TIMEOUT'] || 60
+
+# Node settings overrides
+if File.exist?('nodes.rb')
+  require_relative 'nodes.rb'
+else
+  # Using all defaults
+  NODES = {}
+end
+
+HOSTS = Array(1..SWARM_NODES)
+Vagrant.configure(2) do |vm_config|
+  HOSTS.each do |count|
+    vm_config.vm.define "node#{count}" do |config|
+      config.vm.hostname = "node#{count}"
+      config.vm.box = NODES.dig("node#{count}", 'BOX') || VAGRANT_BOX
+      config.ssh.forward_agent =
+        NODES.dig("node#{count}", 'SSH') || SSH_FORWARD
+
+      # Libvirt
+      config.vm.provider :libvirt do |virt|
+        virt.memory = NODES.dig("node#{count}", 'MEM') || VAGRANT_MEM
+        virt.cpus = NODES.dig("node#{count}", 'CPU') || VAGRANT_CPU
+      end
+
+      # VirtualBox
+      config.vm.provider :virtualbox do |vbox|
+        vbox.memory = NODES.dig("node#{count}", 'MEM') || VAGRANT_MEM
+        vbox.cpus = NODES.dig("node#{count}", 'CPU') || VAGRANT_CPU
+      end
+
+      # Install and Setup Docker Swarm
+      config.vm.provision "shell", inline: <<-SHELL
+        export JOIN_TIMEOUT=#{JOIN_TIMEOUT}
+        /bin/bash /vagrant/provision.sh
+      SHELL
+    end
+  end
+end

example-.settings.yml

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+########################
+### Example settings ###
+########################
+
+# This configuration as-is will take 12 threads/cores and 12 GB of RAM
+# Make sure you have enough resources before running something like this.
+
+# Set per-node overrides in nodes.rb if your setup requires it
+
+# Vagrant default global overrides
+VAGRANT_BOX: debian/bookworm64
+VAGRANT_CPUS: 4
+VAGRANT_MEM: 4096
+SSH_FORWARD: true
+
+# Swarm default overrides
+SWARM_NODES: 3
+JOIN_TIMEOUT: 60

example-nodes.rb

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+#########################
+### Example overrides ###
+#########################
+
+# This configuration as-is will take 10 threads/cores and 10 GB of RAM assuming
+# that .settings.yml isn't overriding the defaults. Make sure you have enough
+# resources before running something like this.
+
+# Don't forget to set SWARM_NODES in .settings
+# if you run more/less than 3 nodes
+
+NODES = {
+  # CPU/MEM heavy node
+  'node1' => {
+    #'BOX'  => 'debian/bookworm64',
+    'CPU' => 4,
+    'MEM'  => 4096,
+    'SSH'  => true
+  },
+  # Memory heavy node
+  'node2' => {
+    'BOX'  => 'debian/bookworm64',
+    #'CPU' => 4,
+    'MEM'  => 4096,
+    #'SSH'  => true
+  },
+  # CPU heavy node
+  'node3' => {
+    'BOX'  => 'debian/bookworm64',
+    'CPU' => 4,
+    #'MEM'  => 4096,
+    #'SSH'  => true
+  }
+}

provision.sh

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+#!/bin/bash
+
+######################################
+### Install and setup Docker Swarm ###
+######################################
+
+# Print commands and exit on error
+set -xe
+
+# Install Docker
+which curl &>/dev/null || (apt-get update && apt-get install -y curl)
+which docker &>/dev/null || curl -fsSL https://get.docker.com | sh
+[ ! "$(id -nG "$USER" | grep -c docker)" -eq 1 ] && usermod -aG docker "$USER"
+
+# Setup Docker Swarm
+if [ ! "$(docker info | grep -c 'Swarm: active')" -eq 1 ]; then
+  # Make hostname: node1 the leader who gives the join token to others
+  if [ "$(hostname)" == "node1" ]; then
+    docker swarm init | grep -Eo 'docker swarm join .+:[0-9]+' > /vagrant/.swarm
+  else
+    # Waits JOIN_TIMEOUT of seconds to find the swarm join token before giving up
+    START_TIME="$(date +%s)"
+    # Initial wait
+    sleep 5
+    # Wait until .swarm can be found via Vagrant provider file sharing
+    while [ ! -f /vagrant/.swarm ]; do
+      CURRENT_TIME="$(date +%s)"
+      DIFF_TIME="$((CURRENT_TIME - START_TIME))"
+
+      # Timeout
+      if [ "$DIFF_TIME" -ge "$JOIN_TIMEOUT" ]; then
+        echo "[ERROR]: $(hostname) waited $DIFF_TIME/$JOIN_TIMEOUT seconds"
+        exit 1
+      fi
+
+      # Waiting
+      echo "Waiting ($DIFF_TIME/$JOIN_TIMEOUT seconds) for /vagrant/.swarm file"
+      sleep 10
+    done
+
+    # /vagrant/.swarm file found, so join the swarm
+    /bin/bash /vagrant/.swarm
+    fi
+fi

scratch/.gitignore

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+*
+!.gitignore