Docker Swarm

• Source: https://github.com/moby/moby
• License: Apache 2.0
• Alternatives: Kubernetes, k3s, Nomad
• Status: RIP — networking was annoying and added complexity for env variables

Multi-server Docker orchestration.

Features

• Native Docker Integration: Built into Docker Engine — no extra tools to install
• Multi-Host Networking: Encrypted overlay networks spanning multiple machines
• Service Scaling: Scale containers up or down with a single command
• Rolling Updates & Rollbacks: Deploy new images with zero downtime and easy rollback
• Node Placement Constraints: Pin services to specific nodes via labels
• Built-In Secrets Management: Securely distribute credentials to services

Setup Network

docker network create \
  --driver overlay \
  --attachable \
  --opt encrypted \
  exist

Setup Swarm (Manager First)

docker swarm init --advertise-addr <MANAGER-IP>
# Save the output token to add workers

Deploy the registry:

docker stack deploy -c docker-compose.yml registry

Join Swarm (Worker)

Run the join command returned from the manager init step.

Pin Service to Node

deploy:
  placement:
    constraints:
      - node.labels.has_local_ssd == true

# List nodes
docker node ls

# Label a node
docker node update --label-add has_local_ssd=true {hostname}