A Multi-Service Multi-Node Web App

Creating networks, volumes, and services for a web-based "cats vs. dogs" voting app.

Here is a basic diagram of how the 5 services will work:

• All images are on Docker Hub, so all commands are written inside commands.sh file. We can paste those commands into swarm shell.
• a backend and frontend overlay networks are needed. Nothing different about them other than that backend will help protect database from the voting web app. (similar to how a VLAN setup might be in traditional architecture)
• The database server should use a named volume for preserving data. Using --mount format to do this: --mount type=volume,source=db-data,target=/var/lib/postgresql/data

Services (names below should be service names)

• vote

  • adityahajare/examplevotingapp_vote
  • web front end for users to vote dog/cat
  • ideally published on TCP 80. Container listens on 80
  • on frontend network
  • 2+ replicas of this container

• redis

  • redis:3.2
  • key/value storage for incoming votes
  • no public ports
  • on frontend network
  • 1 replica NOTE VIDEO SAYS TWO BUT ONLY ONE NEEDED

• worker

  • adityahajare/examplevotingapp_worker:java
  • backend processor of redis and storing results in postgres
  • no public ports
  • on frontend and backend networks
  • 1 replica

• db

  • postgres:9.4
  • one named volume needed, pointing to /var/lib/postgresql/data
  • on backend network
  • 1 replica
  • remember set env for password-less connections -e POSTGRES_HOST_AUTH_METHOD=trust

• result

  • adityahajare/examplevotingapp_result
  • web app that shows results
  • runs on high port since just for admins (lets imagine)
  • so run on a high port of your choosing (I choose 5001), container listens on 80
  • on backend network
  • 1 replica