architecture - Microservice Authentication strategy

Question

I'm having a hard time choosing a decent/secure authentication strategy for a microservice architecture. The only SO post I found on the topic is this one: Single Sign-On in Microservice Architecture

My idea here is to have in each service (eg. authentication, messaging, notification, profile etc.) a unique reference to each user (quite logically then his user_id) and the possibility to get the current user's id if logged in.

From my researches, I see there are two possible strategies:

1. Shared architecture

In this strategy, the authentication app is one service among other. But each service must be able to make the conversion session_id => user_id so it must be dead simple. That's why I thought of Redis, that would store the key:value session_id:user_id.

2. Firewall architecture

In this strategy, session storage doesn't really matter, as it is only handled by the authenticating app. Then the user_id can be forwarded to other services. I thought of Rails + Devise (+ Redis or mem-cached, or cookie storage, etc.) but there are tons of possibilities. The only thing that matter is that Service X will never need to authenticate the user.

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How do those two solutions compare in terms of:

• security
• robustness
• scalability
• ease of use

Or maybe you would suggest another solution I haven't mentioned in here?

I like the solution #1 better but haven't found much default implementation that would secure me in the fact that I'm going in the right direction.

Answer 1

Based on what I understand, a good way to resolve it is by using the OAuth 2 protocol (you can find a little more information about it on http://oauth.net/2/)

When your user logs into your application they will get a token and with this token they will be able to send to other services to identify them in the request.

Example of Chained Microservice Design

Resources:

• http://presos.dsyer.com/decks/microservice-security.html
• https://github.com/intridea/oauth2
• https://spring.io/guides/tutorials/spring-security-and-angular-js/