URL Shortener Service

Contents

• Requirements
• Tasks
• APIs
• System Design
  • Overview
  • URL Shortening
• Sequence Diagram
  • URL Shortening
  • URL Redirection
• How to Run
  • Host OS
  • Docker
  • Kubernetes
• Test
  • Unit Test
  • Load Test
• How to Finalize
• Commands

Requirements

• It shortens the given URLs.
• It redirects to the original URL by getting a shortened URL.
• It provides metrics for monitoring.
• Scalability, Availability, Reliability.

Tasks

• APIs: url shortening, redirection, swagger UI, metrics
• Code Formatting w/ make format
• Code Linting w/ make lint
• Dockerfile and docker-compose.yaml
• Unit Test w/ echo testing
• Load Balancer (k8s)
• Auto Scaling (k8s)
• Monitoring: Server Metrics w/ Prometheus & Grafana (k8s)
• Monitoring: Server Logs w/ Promtail & Loki & Grafana (k8s)
• Load Tests w/ Locust
• Redis failure fix on M1 mac (k8s - minikube)
• Ingress w/ Traefik (k8s)
• TLS (k8s)
• Frontend

APIs

POST /shorten  # it returns a key value for shortened url
GET  /:key     # it redirects to the original url
GET  /docs     # swagger UI
GET  /metrics  # prometheus metrics

You can simply test it with curl.

$ curl -X 'POST' 'http://localhost:8080/shorten' \
    -H 'accept: application/json' \
    -H 'Content-Type: application/json' \
    -d '{ "url": "https://www.google.com/search?q=longlonglonglonglonglonglonglonglonglonglongurl" }'

{"key":"M8uIUx0W000"}

Go to http://localhost:8080/M8uIUx0W000 on your browser.

System Design

Overview

• Server: Echo (Golang)
• Database: Redis

URL Shortening

flowchart TD
  Start --> A
  A[Input: originalURL] --> B{Is it in DB?}
  B -->|Yes| C[Return the key for the short URL from DB]
  B -->|No| D[Generate an unique int64 value with snowflake]
  D --> E[Convert the unique key into a Base62 string]
  E --> F[Store the originalURL and the key]
  F --> C
  C --> End

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Sequence Diagram

URL Shortening

sequenceDiagram
  autonumber
  actor U as User
  participant S as Server
  participant D as Database
  U ->> S: HTTP Req. POST Shortened URL {url}
  S ->> D: HTTP Req. GET Shortened URL {key}
  D -->> S: HTTP Resp. {key, exist}
  alt if not exists
    S ->> S: Generate Short URL key
    S ->> D: Store URL and key
  end
  S -->> U: HTTP Resp. Shortened URL key {key}

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URL Redirection

sequenceDiagram
  autonumber
  actor U as User
  participant S as Server
  participant D as Database
  U ->> S: HTTP Req. GET Original URL {key}
  S ->> D: HTTP Req. GET Original URL {key}
  D -->> S: HTTP Resp. {originalURL, exist}
  alt if not exists
    S -->> U: HTTP Resp. Not Found
  else
    S -->> U: HTTP Resp (Redirect). Found {originalURL}
  end

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How to Run

Option 1: Host OS

This repository is tested on:

• redis-server: v7.0.5
• M1 MacMini (2020)

Install redis, golang, and run:

$ redis-server
$ make run  # in another terminal

Option 2: Docker

This repository is tested on:

• docker engine: v20.10.12
• docker-compose: v1.29.2
• M1 MacMini (2020)

Install docker and run:

$ docker-compose up

Option 3: Kubernetes

This repository is tested on:

• minikube v1.29.0
• kubectl 1.26.1
• M1 MacMini (2020)

Install minikube and run:

make cluster  # init the k8s cluster
make charts   # install charts
# Check all pods are running
# kubectl get pods

Access to URL-Shortener

Add host information in /etc/hosts:

127.0.0.1 url-shortener.local
127.0.0.1 grafana.url-shortener.local

Expose grafana and url-shortner:

minikube tunnel

Now, you can access url-shortener service through https://url-shortener.local/ .

To open swagger UI, open https://url-shortener.local/docs/index.html

Access to Grafana

Open Grafana on the web-browser: https://grafana.url-shortener.local/

• id: admin
• pw: prom-operator

Let's configure loki as data sources to monitor the service logs.

• Configuration -> Data sources -> Add data sources

• Select Loki

• Add URL: http://loki.default.svc.cluster.local:3100
• Click Save & test on the bottom.

• Explore -> Select Loki

• job -> default/url-shortner -> Show logs

• Ta-da!

• You can see the server metrics as well: Explore -> Prometheus -> job -> url-shortener -> Use query.

• Ta-da!

Test

Unit Tests

make utest

Load tests

You will need to install Python3 for this.

pip install locust  # just at the first beginning
make ltest

You need to Open http://localhost:8089/

Scenario: Every v-user sends a request of shortening URL or redirection once a second.

• tests with docker-compose.yaml
• Mac Mini 2020

NOTE: By default, minikube starts with 2 CPUs and 2GB of memory, so it shows lower performance than docker-compose settings.

Finalize

You can clear the cluster by running:

make finalize

Commands

make run            # build and run the project
make run-profile    # build and run the project with profiler
make setup-dev      # install go packages

# below commands are available after `make setup-dev`
make docs           # generate swagger ui
make format         # format the codes
make lint           # lint the codes

# tests
make utest          # run unit tests
make cover          # check the unit test coverage
make ltest          # load test w/ locust

# k8s
make cluster        # create a minikube (k8s) cluster
make charts         # install all services
make remove-charts  # remove all services
make finalize       # finalize the cluster