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Authentication and Authorization in a Microservices Architecture
by Gustavo Peixoto de Azevedo

Authentication and Authorization in a Microservices Architecture

Authentication and Authorization are critical issues in any system. A distributed system as an Event-Driven collection of Microservices running on the cloud adds additional challenges for these issues.

This post recapitulates the characteristics of an Event-Driven Microservices Architecture, what is Authentication and Authorization, explains the requirements for a Solution, and finally proposes a solution that addresses these requirements.

Microservices Architecture

All companies to survive and grow need to embrace, adapt and innovate with technologies that can improve and change their business models and operations to enable a more competitive business relationship with the market. Digital technologies are evolving fast and having widespread adoption. The current business scenario is been reshaped by transformations enabled by these technologies, enabling new business models and turning others obsolete.

IT business systems are the main tool to implement business models and operations. Microservices Architecture is the prominent software architecture that addresses the needs of current IT business systems:

  • experiment fast
  • learn fast
  • evolve fast

A Microservices Architecture has the following characteristics:

  • Composed by autonomous specialized services
  • Each service intrinsically related to a business subdomain
  • Multiple technologies: each service can be implemented using the most convenient technology

Event Driven Microservices

  • Loosed coupled services
  • Intercomunication via messages

Authentication

Identification of the user. To check the identity of an user based on the credentials received. The identification of an user can be composed of atributes that define roles. The authentication can be a system service.

Authorization

Permissions assigned for an user. To determine if the identified user should be granted access to a particular resource. Authorization can be specific for each service. User relationships with domain data are determined in the service context. Resource server.

Requirements for a Solution

  • Authentication in the first interaction in a user session
  • Authentication Persistance during a user session
  • Existence of a Mechanism for Authentication invalidation during a session
  • Authorization based on user, context and data
  • Minimal overhead in each Microservices

A solution

  • Client / Server Communication:

    • Cookies as transport mechanism
    • JWT for storing pertinent information about the user
  • System Components:

    • Authentication Service
    • Authorization Service
    • Message Mechanism
  • Microservice add-ons:

    • Authentication Sidecar
    • Autorization Sidecar

Data based Authentication and Authorization

JWT are access tokens JWT enables stateless authorization

Json Web Token is a compact URL-safemeans ofrepresenting claims to be transfered between two parties. The claims are encoded as JSON object that is digitaly assigned by hashing itusing a shared secret between the parties.

A secure way to transit to encapsulate arbitary data that can be sent over unsecure URLs. Securely send a payload. A JWT is composed of a Header, a payload (claims), and a signature.

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