How to configure oAuth2 with password flow with Swagger ui in spring boot rest application

After 8 months, finally the password flow is supported in Swagger UI, here is the final code and settings which works for me:

1) Swagger Config:

package com.example.api;


import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.bind.annotation.RequestMethod;
import springfox.documentation.schema.ModelRef;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.service.AuthorizationScope;
import springfox.documentation.service.Contact;
import springfox.documentation.service.GrantType;
import springfox.documentation.service.OAuth;
import springfox.documentation.service.ResourceOwnerPasswordCredentialsGrant;
import springfox.documentation.service.ResponseMessage;
import springfox.documentation.service.SecurityReference;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.builders.ResponseMessageBuilder;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spi.service.contexts.SecurityContext;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger.web.ApiKeyVehicle;
import springfox.documentation.swagger.web.SecurityConfiguration;
import springfox.documentation.swagger2.annotations.EnableSwagger2;
import java.util.Collections;
import java.util.List;

import static com.google.common.collect.Lists.*;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

    @Value("${app.client.id}")
    private String clientId;
    @Value("${app.client.secret}")
    private String clientSecret;
    @Value("${info.build.name}")
    private String infoBuildName;

    @Value("${host.full.dns.auth.link}")
    private String authLink;

    @Bean
    public Docket api() {

        List<ResponseMessage> list = new java.util.ArrayList<>();
        list.add(new ResponseMessageBuilder().code(500).message("500 message")
                .responseModel(new ModelRef("Result")).build());
        list.add(new ResponseMessageBuilder().code(401).message("Unauthorized")
                .responseModel(new ModelRef("Result")).build());
        list.add(new ResponseMessageBuilder().code(406).message("Not Acceptable")
                .responseModel(new ModelRef("Result")).build());

        return new Docket(DocumentationType.SWAGGER_2).select().apis(RequestHandlerSelectors.any())
                .paths(PathSelectors.any()).build().securitySchemes(Collections.singletonList(securitySchema()))
                .securityContexts(Collections.singletonList(securityContext())).pathMapping("/")
                .useDefaultResponseMessages(false).apiInfo(apiInfo()).globalResponseMessage(RequestMethod.GET, list)
                .globalResponseMessage(RequestMethod.POST, list);



    }

    private OAuth securitySchema() {

        List<AuthorizationScope> authorizationScopeList = newArrayList();
        authorizationScopeList.add(new AuthorizationScope("read", "read all"));
        authorizationScopeList.add(new AuthorizationScope("trust", "trust all"));
        authorizationScopeList.add(new AuthorizationScope("write", "access all"));

        List<GrantType> grantTypes = newArrayList();
        GrantType creGrant = new ResourceOwnerPasswordCredentialsGrant(authLink+"/oauth/token");

        grantTypes.add(creGrant);

        return new OAuth("oauth2schema", authorizationScopeList, grantTypes);

    }

    private SecurityContext securityContext() {
        return SecurityContext.builder().securityReferences(defaultAuth()).forPaths(PathSelectors.ant("/user/**"))
                .build();
    }

    private List<SecurityReference> defaultAuth() {

        final AuthorizationScope[] authorizationScopes = new AuthorizationScope[3];
        authorizationScopes[0] = new AuthorizationScope("read", "read all");
        authorizationScopes[1] = new AuthorizationScope("trust", "trust all");
        authorizationScopes[2] = new AuthorizationScope("write", "write all");

        return Collections.singletonList(new SecurityReference("oauth2schema", authorizationScopes));
    }

    @Bean
    public SecurityConfiguration securityInfo() {
        return new SecurityConfiguration(clientId, clientSecret, "", "", "", ApiKeyVehicle.HEADER, "", " ");
    }

    private ApiInfo apiInfo() {
        return new ApiInfoBuilder().title("My API title").description("")
                .termsOfServiceUrl("https://www.example.com/api")
                .contact(new Contact("Hasson", "http://www.example.com", "[email protected]"))
                .license("Open Source").licenseUrl("https://www.example.com").version("1.0.0").build();
    }

}

2) in POM use this Swagger UI version 2.7.0:

    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>2.7.0</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>2.7.0</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-bean-validators</artifactId>
        <version>2.7.0</version>
    </dependency>

3) in the application.properties add the following properties:

host.full.dns.auth.link=http://oauthserver.example.com:8081
app.client.id=test-client
app.client.secret=clientSecret
auth.server.schem=http

4) in the Authorisation server add a CORS filter:

package com.example.api.oauth2.oauth2server;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * Allows cross origin for testing swagger docs using swagger-ui from local file
 * system
 */
@Component
public class CrossOriginFilter implements Filter {
    private static final Logger log = LoggerFactory.getLogger(CrossOriginFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

        // Called by the web container to indicate to a filter that it is being
        // placed into service.
        // We do not want to do anything here.
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
            throws IOException, ServletException {

        log.info("Applying CORS filter");
        HttpServletResponse response = (HttpServletResponse) resp;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
        response.setHeader("Access-Control-Max-Age", "0");
        chain.doFilter(req, resp);
    }

    @Override
    public void destroy() {

        // Called by the web container to indicate to a filter that it is being
        // taken out of service.
        // We do not want to do anything here.
    }
}

If you run with these settings you will get the authorize button in the link http://apiServer.example.com:8080/swagger-ui.html#/ (if you run on 8080) as follows:

Then when you click on the authorize button you will get the following dialogue, add the data for your username/password and the client id and the client secret, the type has to be request body, I am not sure why but this is what works with me, although I thought it should be basic auth as this is how the client secret is sent, anyway this is how Swagger-ui works with password flow and all your API endpoints are working again. Happy swaggering!!! :)