muCon 2016: Authentication in Microservice Systems By David Borsos
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The document discusses authentication and authorization challenges in microservice architectures, highlighting issues such as shared user databases and ownership of credentials. It presents various solutions including Single Sign-On (SSO), distributed sessions, client-side tokens, and the use of API gateways, evaluating their security, statelessness, and integration complexity. The document emphasizes the need for robust authentication mechanisms to ensure security without compromising the microservices' independence and scalability.
muCon 2016: Authentication in Microservice Systems By David Borsos
- 1. @davib0 Authentication in Microservice Systems David Borsos
- 2. @davib0 Authentication and Authorisation in Microservice Systems David Borsos
- 3. @davib0 Authentication and Authorisation in Microservice Systems David Borsos
- 4. @davib0 End-user Authentication and Authorisation in Microservice Systems David Borsos
- 5. @davib0 Introduction David Borsos Joined OpenCredo in 2013 Working on microservices since then Email: [email protected] Twitter: @davib0 http://www.opencredo.com
- 6. @davib0 Why?
- 11. @davib0 μServices! ● Composing functionality ● Self-contained services ● “Bounded context” ● Independent scaling ● Independent deployment ○ Containers ○ Schedulers ■ Kubernetes ■ Mesos + Marathon ○ PaaS(es) ■ CloudFoundry ● Localized failures ● Prefer statelessness ○ Don’t rely on HTTP Sessions
- 13. @davib0 μServices - Let’s try the same pattern
- 14. @davib0 μServices - Let’s try the same pattern Problem #1 - shared user database
- 16. @davib0 μServices Problem #1 - shared user database
- 17. @davib0 μServices Problem #1 - shared user database Solution #1 - distribute!
- 18. @davib0 μServices Problem #1 - shared user database Solution #1 - distribute! Problem #2 - who owns the credentials?
- 20. @davib0 μServices Problem #1 - shared user database Solution #1 - distribute! Problem #2 - who owns the credentials?
- 21. @davib0 μServices Problem #1 - shared user database Solution #1 - distribute! Problem #2 - who owns the credentials? Solution #2 - Authentication Service
- 22. @davib0 μServices Problem #1 - shared user database Solution #1 - distribute! Problem #2 - who owns the credentials? Solution #2 - Authentication Service Problem #3 - switching services
- 26. @davib0 μServices - what do we want? ● “Secure” ○ Security is complex ○ Client-side ○ Sharing secrets? ● Stateless services ○ Multiple instances ● No single point of failure ○ On every request ○ When switching services ● No inherent bottlenecks ● Transparency ● Logout? ● Integration with μServices ● Simple to implement
- 27. @davib0 μServices 1. Use SSO solutions 2. Distributed session 3. Client-side token 4. Client-side token + API Gateway
- 29. @davib0 Detour: how do these work?
- 30. @davib0 A common SSO pattern 1. User requests access 2. Not authenticated 3. User authenticates with SSO Server 4. Authentication successful, grant token 5. User uses token 6. Application uses token to get user details 7. Auth Server returns details +1 Auth server maintains “global login” +2 Application maintains “local login”
- 31. @davib0 Using SSO solutions ● SSO “login” state is usually opaque ● SSO Service becomes SPOF ● Chatty traffic ● Every switch potentially requires SSO ○ Optimise with local “login” caching
- 32. @davib0 Using SSO solutions Security As good as the chosen SSO ✔ Secret sharing No ✔ Statelessness Relies on HTTP sessions ✘ SPOF @ service switch Authentication server ✘ Bottlenecks Authentication server (switch only) ! Transparent Yes ✔ Logout Complex ✘ Technologies CAS, OAuth2* ✔ Integration Good library support ✔ Implementation Fairly high complexity ✘
- 34. @davib0 Distributed sessions 1. User requests access 2. Not authenticated 3. User authenticates with Auth Service 4. Authentication successful a. Write state to distributed Session Store i. User X is logged in ii. Sets TTL b. Sets Session ID on client side 5. User uses Session ID 6. μService read distributed Session Store a. Refresh TTL
- 35. @davib0 Distributed sessions Security Opaque, rotatable Session ID ✔ Secret sharing Access to session store ✘ Statelessness Shared state ✔ SPOF @ service switch Session store* ! Bottlenecks Session store (every request) ✘ Transparent Yes ✔ Logout Trivial - delete shared session ✔ Technologies Redis, Cassandra, Hazelcast, Riak ✘ Integration Custom implementation ✘ Implementation Medium/High complexity !
- 37. @davib0 3. “Poor man’s certificates”
- 38. @davib0 Client side tokens 1. User requests access 2. Not authenticated 3. User authenticates with Auth Server 4. Authentication successful a. Set ID token on the client side i. Self-contained ii. Signed iii. TTL 5. Services understand ID token a. Can parse user ID b. Can verify token i. Check signature ii. Check TTL
- 39. @davib0 Detour: JSON Web Tokens (JWT)
- 40. @davib0 JWT eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzd WIiOiJteVVzZXJJZCIsIm5hbWUiOiJKb2huIERv ZSJ9.00q6RI76-oOyQIoshomTVIfmebQPGoDV 2znTErEJjjo Header { "alg": "HS256", "typ": "JWT" } Body { "sub": "myUserId", "name": "John Doe" } Signature
- 41. @davib0 JWT ● Standard ● Simple ● Extensible ● Can use a variety of signatures (SHA or RSA) ● Good library support ● Symmetric or Public/Private key signatures ● http://jwt.io
- 42. @davib0 Client side tokens 1. User requests access 2. Not authenticated 3. User authenticates with Auth Server 4. Authentication successful a. Set ID token on the client side i. Self-contained ii. Signed iii. TTL 5. Services understand ID token a. Can parse user ID b. Can verify token i. Check signature ii. Check TTL
- 43. @davib0 But...
- 44. @davib0 ...token is valid until TTL...
- 45. @davib0 ...and μServices accept it...
- 47. @davib0 Client-side tokens: Logout ● Remove token from client-side store ● Periodically check with Auth Service (“renew token”) ● CRL-style revocation ○ Maintain list of revoked tokens ○ Distribute list across μServices (messaging middleware) ● Use short-lived (15m) tokens
- 48. @davib0 Client-side tokens Security Potentially exposing User IDs ! Secret sharing Depends on signature algorithm ! Statelessness Completely stateless ✔ SPOF @ service switch None ✔ Bottlenecks None ✔ Transparent Yes ✔ Logout Complex* (for server-side) ! Technologies JWT, OpenID Connect ✔ Integration Good library support ✔ Implementation Simple ✔
- 49. @davib0 4. Client-side tokens + API Gateway
- 50. @davib0 Client-side tokens + API Gateway 1. User requests access 2. Not authenticated 3. User authenticates with Auth Server 4. Authentication successful a. Set ID token on the client side i. Self-contained ii. Signed iii. TTL 5. API Gateway translates to opaque token 6. API Gateway resolves to ID token 7. Services understand ID token a. Can parse user ID b. Can verify token i. Check signature ii. Check TTL
- 51. @davib0 API Gateways ● Proxying all user-facing communication ● Fairly simple ● Needs data store (for this use-case) ● Not a distributed session ○ μServices don’t interact with token store ○ μServices are not API Gateway-aware ● Logout ○ Revoke tokens in API Gateway’s token store
- 52. @davib0 Client-side tokens + API Gateway Security Opaque, rotatable Session ID ✔ Secret sharing Depends on signature algorithm ! Statelessness Some state held in API GW ! SPOF @ service switch None ✔ Bottlenecks API Gateway ! Transparent Yes ✔ Logout Trivial ✔ Technologies JWT, nginx, distributed DB, Kong ! Integration Good library support ✔ Implementation Fairly high complexity ✘
- 53. @davib0 Summary
- 54. @davib0 SSO Distributed Session JWT API GW Security ✔ ✔ ! ✔ Secret sharing ✔ ✘ ! ! Statelessness ✘ ✔ ✔ ! SPOF @ service switch ✘ ! ✔ ✔ Bottlenecks ! ✘ ✔ ! Transparent ✔ ✔ ✔ ✔ Logout ✘ ✔ ! ✔ Technologies ✔ ✘ ✔ ! Integration ✔ ✘ ✔ ✔ Implementation ✘ ! ✔ ✘