I’m building a Spring Boot application that processes requests from a chatbot service and returns relevant data. The app needs to connect to external APIs that require OAuth2 authentication to fetch additional information.
The Challenge I’m Facing
I’ve stored my API credentials in the application.yml configuration file. However, most OAuth2 examples I find online show user authentication flows where users log in through social media accounts like Google or Twitter.
What I actually need is different - my backend service should authenticate directly with external APIs using client credentials, without any user interaction involved.
What I’m Looking For
Can anyone share examples or best practices for implementing machine-to-machine OAuth2 authentication in Spring Boot? I want my service to automatically get access tokens using stored credentials and make authenticated API calls to external services.
interesting challenge! i’m curious tho - are you planning to hit multiple different oauth2 providers or just one main API? also wondering if you’ve considerd token caching strategies since those access tokens usually expire pretty quick. what’s your expected request volume looking like?
I encountered this exact scenario when integrating with multiple vendor APIs in my Spring Boot application. The OAuth2 Client Credentials flow is what you need for machine-to-machine authentication. Spring Security 5+ provides excellent support through WebClient with OAuth2 authorization. Configure your credentials in application.yml under spring.security.oauth2.client.registration and spring.security.oauth2.client.provider sections. Then inject WebClient with .oauth2Client() filter to automatically handle token acquisition and refresh. The framework manages token lifecycle, caching, and renewal transparently. Make sure to use @ConfigurationProperties to bind your OAuth2 settings rather than hardcoding values. This approach has been rock-solid in production environments handling thousands of API calls daily without manual token management overhead.
oauth2 client credentials grant is definitly the way to go here. i use RestTemplate with ClientCredentialsResourceDetails and it works great for server-to-server auth. just set your clientId, clientSecret, and accessTokenUri in the config and spring handles the token stuff automatically. way simpler than webclient imo