Docker Swarm - A Multi-Service Multi-Node Web App

Author: aditya43

10-Swarm-Multi-Service-Multi-Node-Web-App/README.md

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+# 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:
+
+![diagram](./architecture.png)
+- 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

10-Swarm-Multi-Service-Multi-Node-Web-App/architecture.png

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+docker network create -d overlay backend
+docker network create -d overlay frontend
+
+docker service create --name vote -p 80:80 --network frontend --replicas 2 adityahajare/examplevotingapp_vote
+
+docker service create --name redis --network frontend redis:3.2
+
+docker service create --name db --network backend -e POSTGRES_HOST_AUTH_METHOD=trust --mount type=volume,source=db-data,target=/var/lib/postgresql/data postgres:9.4
+
+docker service create --name worker --network frontend --network backend adityahajare/examplevotingapp_worker:java
+
+docker service create --name result --network backend -p 5001:80 adityahajare/examplevotingapp_result