I just announced the newSpring Security 5 modules (primarily focused on OAuth2) in the course:
Table of Contents
- 1. Overview
- 2. Setting up the RestTemplate in Spring
- 3. Manual management of the Authorization HTTP header
- 4. Automatic management of the Authorization HTTP header
- 5. Maven dependencies
- 6. Conclusion
1. Overview
This article shows how to use Springs RestTemplate to consume a RESTful Service secured with Basic Authentication.
Once Basic Authentication is set up for the template, each request will be sent preemptively containing the full credentials necessary to perform the authentication process. The credentials will be encoded and will use the Authorization HTTP Header, in accordance with the specs of the Basic Authentication scheme. An example would look like this:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
2. Setting up the RestTemplate
Bootstrapping the RestTemplate into the Spring context can be done by simply declaring a bean for it; however, setting up the RestTemplate with Basic Authentication will require manual intervention, so instead of declaring the bean directly, a Spring FactoryBean will be used for more flexibility. This factory will create and configure the template on initialization:
import org.apache.http.HttpHost; import org.springframework.beans.factory.FactoryBean; import org.springframework.beans.factory.InitializingBean; import org.springframework.stereotype.Component; import org.springframework.web.client.RestTemplate; @Component public class RestTemplateFactory implements FactoryBean<RestTemplate>, InitializingBean { private RestTemplate restTemplate; public RestTemplate getObject() { return restTemplate; } public Class<RestTemplate> getObjectType() { return RestTemplate.class; } public boolean isSingleton() { return true; } public void afterPropertiesSet() { HttpHost host = new HttpHost("localhost", 8080, "http"); restTemplate = new RestTemplate( new HttpComponentsClientHttpRequestFactoryBasicAuth(host)); } }
The host and port values should be dependent on the environment – allowing the client the flexibility to define one set of values for integration testing and another for production use. The values can be managed by the first class Spring support for properties files.
3. Manual Management of the Authorization HTTP Header
The process of creating the Authorization header is relatively straightforward for Basic Authentication, so it can pretty much be done manually with a few lines of code:
HttpHeaders createHeaders(String username, String password){ return new HttpHeaders() {{ String auth = username + ":" + password; byte[] encodedAuth = Base64.encodeBase64( auth.getBytes(Charset.forName("US-ASCII")) ); String authHeader = "Basic " + new String( encodedAuth ); set( "Authorization", authHeader ); }}; }
Then, sending a request becomes just as simple:
restTemplate.exchange (uri, HttpMethod.POST, new HttpEntity<T>(createHeaders(username, password)), clazz);
4. Automatic Management of the Authorization HTTP Header
Both Spring 3.0 and 3.1 and now 4.x have very good support for the Apache HTTP libraries:
- Spring 3.0, the CommonsClientHttpRequestFactory integrated with the now end-of-life’d HttpClient 3.x
- Spring 3.1 introduced support for the current HttpClient 4.x via HttpComponentsClientHttpRequestFactory (support added in the JIRA SPR-6180)
- Spring 4.0 introduced async support via the HttpComponentsAsyncClientHttpRequestFactory
Let’s start setting things up with HttpClient 4 and Spring 4.
The RestTemplate will require an HTTP request factory – a factory that supports Basic Authentication – so far, so good. However, using the existing HttpComponentsClientHttpRequestFactory directly will prove to be difficult, as the architecture of RestTemplate was designed without good support for HttpContext – an instrumental piece of the puzzle. And so we’ll need to subclass HttpComponentsClientHttpRequestFactory and override the createHttpContext method:
import java.net.URI; import org.apache.http.HttpHost; import org.apache.http.client.AuthCache; import org.apache.http.client.protocol.HttpClientContext; import org.apache.http.impl.auth.BasicScheme; import org.apache.http.impl.client.BasicAuthCache; import org.apache.http.protocol.BasicHttpContext; import org.apache.http.protocol.HttpContext; import org.springframework.http.HttpMethod; import org.springframework.http.client.HttpComponentsClientHttpRequestFactory; public class HttpComponentsClientHttpRequestFactoryBasicAuth extends HttpComponentsClientHttpRequestFactory { HttpHost host; public HttpComponentsClientHttpRequestFactoryBasicAuth(HttpHost host) { super(); this.host = host; } protected HttpContext createHttpContext(HttpMethod httpMethod, URI uri) { return createHttpContext(); } private HttpContext createHttpContext() { AuthCache authCache = new BasicAuthCache(); BasicScheme basicAuth = new BasicScheme(); authCache.put(host, basicAuth); BasicHttpContext localcontext = new BasicHttpContext(); localcontext.setAttribute(HttpClientContext.AUTH_CACHE, authCache); return localcontext; } }
It is here – in the creation of the HttpContext – that the basic authentication support is built in. As you can see, doing preemptive Basic Authentication with HttpClient 4.x is a bit of a burden: the authentication info is cached and the process of setting up this authentication cache is very manual and unintuitive.
And with that, everything is in place – the RestTemplate will now be able to support the Basic Authentication scheme just by adding a BasicAuthorizationInterceptor;
restTemplate.getInterceptors().add( new BasicAuthorizationInterceptor("username", "password"));
And the request:
restTemplate.exchange( "http://localhost:8080/spring-security-rest-template/api/foos/1", HttpMethod.GET, null, Foo.class);
For an in-depth discussion on how to secure the REST Service itself, check out this article.
5. Maven Dependencies
The following Maven dependencies are required for the RestTemplate itself and for the HttpClient library:
<dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>4.3.6.RELEASE</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.5.3</version> </dependency>
Optionally, if the HTTP Authorization header is constructed manually, then an additional library is required for the encoding support:
<dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.10</version> </dependency>
You will find the newest versions in the Maven repository.
6. Conclusion
Although the 3.x branch of development for Apache HttpClient has reached the end of life for a while now, and the Spring support for that version has been fully deprecated, much of the information that can be found on RestTemplate and security still doesn’t account for the current HttpClient 4.x releases. This article is an attempt to change that through a detailed, step by step discussion on how to set up Basic Authentication with the RestTemplate and how to use it to consume a secured REST API.
To go beyond the code samples in the article with an implementation of both the consuming side, examined here, but also the actual RESTful Service, have a look at the project over on Github.
This is an Maven-based project, so it should be easy to import and run as it is.
Thank – I updated the code sample.
This has been a very helpful page. I respectfully request that you might consider writing up a little about RestTemplate with Digest Authentication using java configuration code (in lieu of xml type annotation).
Thanks
I’m glad the article was helpful – the other article you mentioned is already written – on Digest Auth.
Thanks. Eugen.
thanks – very useful – I used the manual version
Thanks alot. All your tutorials are great and helped me a lot. I have a Spring Web application where I load my jsps and then through ajax calls interact with rest services. I need to secure both of these, but with basic auth there is no logout/custom login for MVC. Can you suggest something
My suggestion, if this is a reasonable sized application – is to go for a proxy. Client side management of credentials is possible (I had this in the past on simpler projects) – via js libraries (crypto-js among several others) – but it’s somewhat more vulnerable than using the standard cookie based approach with your front end application, and then, from the server side of your front end app, proxy the requests over your REST API (handling the credentials before sending the new request).
A very good post on the subject, if you want to dig deeper.
Cheers,
Eugen.
Thanks alot Eugen. I just checked with my customer and he too is saying no the Client side management. Are any good tutorials or posts available for the proxy based approach. I am new to Spring Security and hence not too familiar with customizing authentication.
Thanks. I will start to look into it. I got the high level idea. But I have no idea where to start, should I look into CAS and single sign-on?
So I have to use a RestTemplate and do getforobject,postforobject… and so on? If yes then I have to change my entire Controller Layer. Or should I have a separate controller layer for js calls? And can using oauth solve this easily?
Yeah Eugen. I understand. I cant thank you enough for helping me out. Thanks a lot.
Cheers!
No worries, hope the project works out well.
Hello sir , where is the download link for the source code
please help
Hey Rajan – did you sign up through the link at the end of the article but haven’t received the code? Cheers,
Eugen.
Hi Eugen,
Can u pls share the source code for this..as when i try to subscribe it sends me the ebook and not the source code…
Hey Marc – to get the full project, sign-up via the link at the very end of the article – the one that says “check out the sample project…” – that should send you the zip. Or email me and I’ll send it over. Cheers,
Eugen.