consul-cluster_docker-compose

• Overview
  • 1 - Components
• Getting Started
  • 1 - Build the image
  • 2 - Update the docker-compose file
  • 3 - Start the cluster
  • 4 - Use the UIs
• Details
  • 1 - Caveats
    • supervisor / Environment variables

Overview

1 - Components

• Base Debian:squeeze
• Supervisor process management
• Consul Agents

Debian Squeeze Base image for Sandbox purpose

• easier to customize
• easier to work with Attached Shell for debugging purpose

Getting Started

1 - Build the image

docker build -t <YOUR_TAG_NAME> --file=Dockerfile .

2 - Update the docker-compose file

docker-compose.yml

Stuff to update:

• Image: Name of the image you have just built;
• Ports: Mapping per instances (to avoid port collision on Host)
• Environment: CONSUL_OPTS (passed to consul agent to define)
  • How many members you want for boostrapping
  • Who to join for the other members
  • What ever other options you would need

$ cat docker-compose.yml
---
consul1:
  image: sandbox/consul-server
  hostname: consul1
  ports:
   - "8301:8300"
   - "8401:8400"
   - "8501:8500"
   - "8601:8600"
   - "9001:9001"
  environment:
   - CONSUL_OPTS=-bootstrap-expect=3

consul2:
  image: sandbox/consul-server
  hostname: consul2
  links:
   - consul1
  ports:
   - "8302:8300"
   - "8402:8400"
   - "8502:8500"
   - "8602:8600"
   - "9002:9001"
  environment:
   - CONSUL_OPTS=-rejoin -retry-join=consul1

...

3 - Start the cluster

docker-compose up


Creating consul1_1...
Creating consul2_1...
Creating consul3_1...
Attaching to consul1_1, consul2_1, consul3_1
...
consul1_1 | 2015-09-18 07:16:27,558 WARN Included extra file "/etc/supervisor/conf.d/01-consul-server.conf" during parsing
...
consul3_1 | 2015-09-18 07:16:29,111 WARN Included extra file "/etc/supervisor/conf.d/01-consul-server.conf" during parsing
...
consul2_1 | 2015-09-18 07:16:28,193 WARN Included extra file "/etc/supervisor/conf.d/01-consul-server.conf" during parsing
...

consul1_1 | 2015-09-18 07:16:30,216 INFO success: consul entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
consul2_1 | 2015-09-18 07:16:30,251 INFO success: consul entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)
consul3_1 | 2015-09-18 07:16:31,208 INFO success: consul entered RUNNING state, process has stayed up for > than 1 seconds (startsecs)

4 - Use the UIs

• Supervisor: [http://DOCKER_IP:900X]
• Consul UI: [http://DOCKER_IP:850X]

Details

1 - Caveats

supervisor / Environment variables

In order to use Environment variables via Docker engine in Supervisor

• => Have to wrapp the consul command with Bash ....

See:

• http://supervisord.org/configuration.html#program-x-section-settings
• http://stackoverflow.com/questions/12900402/supervisor-and-environment-variables
• http://blog.trifork.com/2014/03/11/using-supervisor-with-docker-to-manage-processes-supporting-image-inheritance/

01-consul-server.conf

$ cat supervisor/conf.d/01-consul-server.conf

[program:consul]
directory=/opt/consul

command=/bin/bash -x -c "printenv && /bin/consul agent -config-dir /opt/consul/conf ${CONSUL_OPTS}"

stdout_logfile=/opt/consul/logs/consul-stdout.log
stderr_logfile=/opt/consul/logs/consul-error.log
numprocs=1
autostart=true
autorestart=true
stopsignal=INT