Micro TODO

Trying to write a TODO app with micro services architecture. I am using several technologies just for the sake of using them and getting first-hand experience with them.

Installation

1. Install go-1.9

2. Install Docker

3. Install dep - dep

4. Install dependencies by running dep ensure

5. Run docker build -t micro-todo . to build Docker image

6. Start Docker container from built image

   By default, container runs Registry service. To specify which service to run, append <service name>.bin to the container running command. E.g. docker run -d -p 127.0.0.1:30010:3000 -p 127.0.0.1:8080:80 micro-todo auth.bin

   To start admin web application, go to admin/README.md for instructions

Project structure

• admin - Admin web application for exploring services state
• auth - Auth service
• logger - Logger service
• proto - shared service RPC protocol and generated API gateways
• registry - Registry service
• todo - TODO service
• vendor - project dependencies

Services

Service list

1. Registry - public - list of all available services and load balancing
2. Auth - internal - authorizes and registers users
3. TODO - internal - keeps TODO tasks
4. Admin - admin - provides WEB UI for logs and status of all services
5. Logger - internal - receives logs from all services and provides them to Admin

Service API and configuration

For information about service API and configuration see following files:

• Registry

Communication process

Clients's communication with Auth and TODO through Registry

0. Services register themselves in Registry
1. Client performs request to the Registry to specific service and its API endpoint
2. Registry proxies request to the best instance, converting request to internal protocol, and waits for response
3. On receiving response, Registry converts response from internal protocol to HTTP response and sends back to client

Registry, Auth, TODO services' communication with Logger service

0. Service queries Registry for Logger service
1. Service sends log message to Logger service

Admin service's communication with Logger

0. Admin queries Registry for Logger service
1. Admin queries Logger service for requested service type logs
2. Admin updates log every n seconds
3. Admin queries Registry for services status

Features

• Registry:
  • Works on gRPC
  • Works on HTTP
  • Keeps up-to-date list by performing service instance health checks
  • Supports server-side registering
  • Responses with service types list
  • Responses with service type instances list
  • Responses with address of suitable requested service (balancing)
  • Supports several load balancing algorithms:
    • Random balancer
    • Round-robin balancer
    • Weighted random balancer
    • Weighted round-robin balancer
  • Has health HTTP endpoint
  • Has health RPC method
  • Responses with error message if service is unavailable
  • Restricts querying internal services from external clients
  • Restricts querying admin services from external clients
  • Writes logs to Logger
• Auth:
  • Registers new users
  • Authorizes users
  • Provides auth tokens for authorized users
  • Authenticates users by their auth tokens
• TODO:
  • Stores TODO tasks
  • Stores TODO lists of user
  • Allows adding TODO tasks
  • Allows editing TODO tasks
  • Allows deleting TODO tasks
  • Allows sharing TODO tasks with different users
  • Writes logs to Logger
• Admin:
  • Authenticates admin in WEB UI
  • Collects logs from Logger
  • Shows health status of all services
  • Periodically updates status and logs
• Logger:
  • Receives logs from different services
  • Stores them by service type instances
  • Responses with logs of specific service type instance
  • Persists logs on disks