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71 lines
2.5 KiB
Markdown
71 lines
2.5 KiB
Markdown
# Example Voting App
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A simple distributed application running across multiple Docker containers.
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## Getting started
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Download [Docker Desktop](https://www.docker.com/products/docker-desktop) for Mac or Windows. [Docker Compose](https://docs.docker.com/compose) will be automatically installed. On Linux, make sure you have the latest version of [Compose](https://docs.docker.com/compose/install/).
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This solution uses Python, Node.js, .NET, with Redis for messaging and Postgres for storage.
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Run in this directory to build and run the app:
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```shell
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docker compose up
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```
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The `vote` app will be running at [http://localhost:5000](http://localhost:5000), and the `results` will be at [http://localhost:5001](http://localhost:5001).
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Alternately, if you want to run it on a [Docker Swarm](https://docs.docker.com/engine/swarm/), first make sure you have a swarm. If you don't, run:
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```shell
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docker swarm init
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```
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Once you have your swarm, in this directory run:
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```shell
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docker stack deploy --compose-file docker-stack.yml vote
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```
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## Run the app in Kubernetes
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The folder k8s-specifications contains the YAML specifications of the Voting App's services.
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Run the following command to create the deployments and services objects in the vote namespace:
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```shell
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kubectl create -f k8s-specifications/
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vote "vote" created
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deployment "db" created
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deployment "db" created
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service "db" created
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deployment "redis" created
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service "redis" created
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deployment "result" created
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service "result" created
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deployment "vote" created
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service "vote" created
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deployment "worker" created
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```
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The vote interface is then available on port 31000 on each host of the cluster, the result one is available on port 31001.
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## Architecture
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* A front-end web app in [Python](/vote) which lets you vote between two options
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* A [Redis](https://hub.docker.com/_/redis/) which collects new votes
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* A [.NET](/worker/) worker which consumes votes and stores them in…
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* A [Postgres](https://hub.docker.com/_/postgres/) database backed by a Docker volume
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* A [Node.js](/result) web app which shows the results of the voting in real time
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## Notes
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The voting application only accepts one vote per client browser. It does not register additional votes if a vote has already been submitted from a client.
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This isn't an example of a properly architected perfectly designed distributed app... it's just a simple
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example of the various types of pieces and languages you might see (queues, persistent data, etc), and how to
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deal with them in Docker at a basic level.
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