SpringBoot 3.3 RestClient with Proxy and Authentication: Tackling the 401 Unauthorized Error
This article dives into a common challenge faced when using SpringBoot 3.3's RestClient with a proxy server and basic authentication. Specifically, we'll explore the "401 Unauthorized" error and how to troubleshoot and resolve it. This guide uses real code snippets and explanations, making it a practical resource for developers working with SpringBoot REST APIs.
The Issue:
Many developers encounter a 401 Unauthorized error when setting up their SpringBoot 3.3 applications to communicate with external APIs through a proxy server while implementing basic authentication. The core problem often boils down to the proxy server not receiving the correct credentials.
The Example Code:
The code provided in the question demonstrates a typical approach to configure a proxy and basic authentication:
proxyUrl = "proxy.ops.org";
proxyport = 8080;
CredentialsProvider credsProvider = new BasicCredentialsProvider();
credsProvider.setCredentials(
new AuthScope(proxyUrl, proxyport),
new UsernamePasswordCredentials(username, password)
);
HttpHost myProxy = new HttpHost(proxyUrl, proxyport);
HttpClientBuilder clientBuilder = HttpClientBuilder.create();
clientBuilder.setProxy(myProxy).setDefaultCredentialsProvider(credsProvider);
clientBuilder.setProxy(myProxy).setDefaultCredentialsProvider(credsProvider);
HttpClient httpClient = clientBuilder.build();
HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory();
factory.setHttpClient(httpClient);
RestClient rstCleint = RestClient.builder
.baseUrl("http://test.org")
.requestFactory(factory)
.build();
Troubleshooting the 401 Error:
The debug logs show a key message: "No credentials found for auth scope [Basic 'Test' https://test.org:443]." This indicates that while the proxy server is properly configured, the authentication process is failing because the credentials are not being sent correctly to the proxy.
Solution:
The primary issue arises because the authentication scope in the CredentialsProvider is not correctly set. Instead of using the target API's address (test.org), the authentication scope should be set to the proxy server's address (proxy.ops.org).
Here's the corrected code:
proxyUrl = "proxy.ops.org";
proxyport = 8080;
CredentialsProvider credsProvider = new BasicCredentialsProvider();
credsProvider.setCredentials(
new AuthScope(proxyUrl, proxyport),
new UsernamePasswordCredentials(username, password)
);
HttpHost myProxy = new HttpHost(proxyUrl, proxyport);
HttpClientBuilder clientBuilder = HttpClientBuilder.create();
clientBuilder.setProxy(myProxy).setDefaultCredentialsProvider(credsProvider);
HttpClient httpClient = clientBuilder.build();
HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory();
factory.setHttpClient(httpClient);
RestClient rstCleint = RestClient.builder
.baseUrl("http://test.org")
.requestFactory(factory)
.build();
Explanation:
By changing the AuthScope to new AuthScope(proxyUrl, proxyport), we ensure that the credentials are sent to the proxy server (proxy.ops.org) when establishing a connection. The proxy server can then use these credentials to authenticate with the target API on your behalf.
Additional Notes:
- Proxy Configuration: Ensure that your proxy server is correctly configured within your SpringBoot application.
- Authentication Mechanism: While this article focuses on basic authentication, the same principle applies to other authentication methods like OAuth2. You need to make sure that the credentials are being sent to the correct location for authentication.
- Firewall Rules: Check if any firewall rules might be blocking the communication between your application and the proxy server or the proxy server and the target API.
- Network Connectivity: Verify that your application has proper network connectivity to the proxy server and the target API.
Conclusion:
This article addressed a common issue involving 401 Unauthorized errors while using SpringBoot's RestClient with a proxy and basic authentication. The key takeaway is the importance of setting the correct authentication scope within the CredentialsProvider to ensure the proxy server receives the necessary credentials for authentication.
Remember to carefully analyze the debug logs and pay attention to the authentication scope used for successful proxy and authentication configurations.
Attribution:
The code snippets used in this article are from a question on Stack Overflow. Credit goes to the original author of the question, whose valuable input helped in creating this helpful guide.
