Background:
I am working on a java Spring REST microservice that needs to work with multiple identical back-end systems and multiple identical databases depending on the request parameters.
Basically I have 3 "brands". For each brand there is a set of downstream services and a database. I have no control over those.
My spring service will receive brand as a part of request and will need to call the right downstream services and use the correct database.
Previously I would deal with this by having a separate instance of the spring service for each of the brands. There would be a single property file for each brand and spring would use it to wire up beans. I would have separate URL's for each brand and there was no problem.
Some of my beans need to know about "brand" during creation as they are wrappers around connections downstream services. I.e. once the bean is created there won't be a way to switch it to be a "different brand".
Problem:
I would like to change this so that a single instance of my service can handle requests for any brand.
Requirements:
I was thinking about the following solution:
Have a general property file for non-branded stuff. Spring would wire any non-branded beans and keep them as singleton beans.
Have a property file with brand specific urls etc for each of the brands
Spring would create set of singleton beans for each of the brand using appropriate property file.
Next when the request comes in spring would read the request params and use bean specific for that brand.
Performance is important to me so I would like to reuse the beans as much as possible.
I would like to make this thing as transparent as possible so that people creating new beans don't have to worry about doing anything outside standard configuration/context class.
Does anyone know what would be the best solution to achieve this?
I think you can solve the problem injecting the service in every request with the right set of configurations and beans; possibly already existing in your Application Context.
Given:
$ curl http://localhost:8080/greetings/rodo && echo
Hi from brand1, rodo
$ curl -H "x-brand-name: brand1" http://localhost:8080/greetings/rodo
Hi from brand1, rodo
$ curl -H "x-brand-name: brand2" http://localhost:8080/greetings/rodo && echo
Hi from brand2, rodo
The following code would work:
-- application.yml --
brand1:
greetingPrefix: Hi from brand1,
brand2:
greetingPrefix: Hi from brand2,
-- DemoApplication.java --
#SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#Configuration
class ServiceConfig {
#Bean
public GreetingService greetingServiceBrand1(Brand1Config config) {
return new GreetingService(config);
}
#Bean
public GreetingService greetingServiceBrand2(Brand2Config config) {
return new GreetingService(config);
}
}
#Configuration
class WebConfig implements WebMvcConfigurer {
#Autowired
private ApplicationContext applicationContext;
#Override
public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
resolvers.add(greetingServiceResolver());
}
private GreetingServiceResolver greetingServiceResolver() {
GreetingService greetingServiceBrand1 = applicationContext.getBean("greetingServiceBrand1", GreetingService.class);
GreetingService greetingServiceBrand2 = applicationContext.getBean("greetingServiceBrand2", GreetingService.class);
return new GreetingServiceResolver(greetingServiceBrand1, greetingServiceBrand2);
}
}
}
#RestController
#RequestMapping("/greetings")
class GreetingController {
#GetMapping("/{name}")
public String get(GreetingService greetingService, #PathVariable String name) {
return greetingService.sayHi(name);
}
}
class GreetingServiceResolver implements HandlerMethodArgumentResolver {
private final GreetingService greetingServiceBrand1;
private final GreetingService greetingServiceBrand2;
public GreetingServiceResolver(GreetingService greetingServiceBrand1, GreetingService greetingServiceBrand2) {
this.greetingServiceBrand1 = greetingServiceBrand1;
this.greetingServiceBrand2 = greetingServiceBrand2;
}
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.getParameterType().equals(GreetingService.class);
}
#Override
public Object resolveArgument(
MethodParameter methodParameter,
ModelAndViewContainer modelAndViewContainer,
NativeWebRequest nativeWebRequest,
WebDataBinderFactory webDataBinderFactory
) throws Exception {
String brand = nativeWebRequest.getHeader("x-brand-name");
return resolveGreetingService(brand);
}
private GreetingService resolveGreetingService(String brand) {
if ("brand2".equals(brand)) {
return greetingServiceBrand2;
}
return greetingServiceBrand1; // default
}
}
class GreetingService {
private BaseConfig config;
public GreetingService(BaseConfig config) {
this.config = config;
}
public String sayHi(String name) {
return config.getGreetingPrefix() + " " + name;
}
}
abstract class BaseConfig {
private String greetingPrefix;
public String getGreetingPrefix() {
return greetingPrefix;
}
public void setGreetingPrefix(String greetingPrefix) {
this.greetingPrefix = greetingPrefix;
}
}
#Configuration
#ConfigurationProperties("brand1")
class Brand1Config extends BaseConfig {
}
#Configuration
#ConfigurationProperties("brand2")
class Brand2Config extends BaseConfig {
}
As you can see, it's fundamental to pass the service to each controller method, write a resolver and inject the right set of dependencies depending on a parameter passed to the request, in this case via header.
Since your property files need to be declared statically anyway, you can just write all your different brand stuff in the same property file, like in a key-value format, that Spring can pick up as a list of configurations.
brandConfigs:
- brand: foo
property: foos
- brand2: bar
porperty: bars
Load all your connection beans to your downstream services on startup and just route to them according to your request param. Imo this seems to be the most straight forward and performant way. If some of these downstreams are used very rarely you can lazy load the beans on-demand, but probably this wouldn't make a sense unless you have thousands of different downstream routes.
I want to move my Circuit Breaker Configuration from application.yml file to some config java file as bean declaration beacuse it makes application.yml file to be large, Will it be possible for me to remove the configuration from applciation.yml and use configuration annotation to define circuit breaker configuration.
I have config java file with following code like :
#Configuration
#Component
public class CircuitBreakConfig {
#Bean
public CircuitBreaker defaultCircuitBreaker() {
CircuitBreakerConfig circuitBreakerConfig = CircuitBreakerConfig.custom()
.failureRateThreshold(50)
.slidingWindowSize(5)
.waitDurationInOpenState(Duration.ofMillis(6000))
.recordExceptions(IOException.class, TimeoutException.class,DataIntegrityViolationException.class)
.build();
// Create a CircuitBreakerRegistry with a custom global configuration
CircuitBreakerRegistry circuitBreakerRegistry =
CircuitBreakerRegistry.of(circuitBreakerConfig);
// Get or create a CircuitBreaker from the CircuitBreakerRegistry
// with the global default configuration
return circuitBreakerRegistry.circuitBreaker("default");
}
}
In My service file I am annotating method for circuit breaker like
#CircuitBreaker(name = "default", fallbackMethod = "fallback")
public Employee createEmployeeDefinition(Employee emp) throws Exception{
if(Objects.nonNull(sample)){
return EmployeeRepository.save(sample);
}
return null;
}
public Employee fallback(Employee emp,Exception ex) throws Exception{
System.out.println(ex.getClass()+" "+ex.getMessage() );
return null;
}
With this current implementation , I am unable to reach open state in my circuit breaker.Kindly provide me some suggestions
Please set minimumNumberOfCalls property
This may be silly question to ask but i'm unable to find any satisfactory solution to my problem. In java we don't have the concept of default variables so i am trying to give default value from properties file to my function parameters/arguments using #Value annotation, but i'm always getting null and i'm unable to figure why is this happening. Please help me to solve the issue or provide me some appropriate link/reference which may solve my issue.
MainApplication.java
#SpringBootApplication
public class Application
{
public static void main(String[] args)
{
ApplicationContext context = SpringApplication.run(NetappApplication.class, args);
Sample sample = context.getBean(Sample.class);
System.out.println(sample.check(null));
}
}
Sample.java
public interface Sample
{
public String check(String message);
}
SampleImpl.java
#Service
#PropertySource("classpath:app.properties")
public class SampleImpl implements Sample
{
#Value("${test}")
String message1;
#Override
public String check(#Value("${test}") String message)
{
return message;
}
}
app.properties
test=anand
But you are passing null to your method...
Perhaps what you want to do is to assign default value to test in case it's not defined in property file:
#Value("${test:default}");
Then, when properties are autowired by Spring if placeholder resolver doesn't get the value from props file, it will use what is after :.
The best use case for this (that I can think of) is when you create Spring configuration.
Let's say you have a configuration class: for DB access. Simply put:
#Configuration
public class DbConfig {
#Value("${url:localhost}")
String dbUrl;
// rest for driver, user, pass etc
public DataSource createDatasource() {
// here you use some DataSourceBuilder to configure connection
}
}
Now, when Spring application starts up, properties' values are resolved, and as I wrote above you can switch between value from property and a default value. But it is done once, when app starts and Spring creates your beans.
If you want to check incoming argument on runtime, simple null check will be enough.
#Value("${test}")
String message1;
#Override
public String check(String message) {
if (message == null) {
return message1;
}
}
I want to enable the following jackson mapper feature:
MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES
According to https://docs.spring.io/spring-boot/docs/current/reference/html/howto-spring-mvc.html:
Could be configured in application.properties as follows:
spring.jackson.mapper.accept_case_insensitive_properties=true
But:
#RestController
public class MyServlet {
#RequestMapping("/test")
public void test(#Valid TestReq req) {
}
}
public class TestReq {
#NotBlank
private String name;
}
Usage:
localhost:8080/test?name=test //works
localhost:8080/test?Name=test //fails with 'name may not be blank'
So, the case insensitive property is not taken into account. But why?
By the way: even using Jackson2ObjectMapperBuilderCustomizer explicit does not work:
#Bean
public Jackson2ObjectMapperBuilderCustomizer initJackson() {
Jackson2ObjectMapperBuilderCustomizer c = new Jackson2ObjectMapperBuilderCustomizer() {
#Override
public void customize(Jackson2ObjectMapperBuilder builder) {
builder.featuresToEnable(MapperFeature.ACCEPT_CASE_INSENSITIVE_PROPERTIES);
}
};
return c;
}
spring-boot-1.5.3.RELEASE
According to spring doc you can customize it.
I fix this problem by set my application.yml like this(spring 2.0):
spring:
jackson:
mapper:
ACCEPT_CASE_INSENSITIVE_PROPERTIES: true
Did you tried change your setting accept_case_insensitive_properties to UPPER CASE？
Also you can keep output to Upper Case by setting like this:
jackson:
mapper:
ACCEPT_CASE_INSENSITIVE_PROPERTIES: true
property-naming-strategy: com.fasterxml.jackson.databind.PropertyNamingStrategy.PascalCaseStrategy
Note that PascalCaseStrategy was deprecated now, but still working.
Simple answer: it is not possible.
The Jackson2ObjectMapperBuilderCustomizer affects the JSON POST requests only. It has no effect on the get query binding.
I know you can set the server.contextPath in application.properties to change the root context.
Also, I can add an additional context in the application config for Spring Boot like the following example (in Groovy) to add an "/api" to the URL mappings of the root context:
#Bean
ServletRegistrationBean dispatcherServlet() {
ServletRegistrationBean reg = new ServletRegistrationBean(new DispatcherServlet(), "/")
reg.name = "dispatcherServlet"
reg.addInitParameter("contextConfigLocation", "")
reg.addUrlMappings("/api/*")
reg.loadOnStartup = 2
reg
}
}
I am trying to have a separate base URI "/api" specifically for web service calls, that I can leverage for security, etc. However using the above approach will mean that any of my URIs, web service or not, can be reached with "/" or "/api", and provides no concrete segregation.
Is anyone aware of a better approach to set a base path for all #RestController(s) using configuration, without having to formally prefix every controller with /api/? If I am forced to manually prefix the URI for each controller, it would be possible to mistakenly omit that and bypass my security measures specific to web services.
Here is a reference in Stack Overflow to the same type of question, which was never completely answered:
Spring Boot: Configure a url prefix for RestControllers
In continuation to the currently accepted solution the github issue addresses the same.
Spring 5.1 and above you can implement WebMvcConfigurer and override configurePathMatch method like below
#Configuration
#EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
#Override
public void configurePathMatch(PathMatchConfigurer configurer) {
configurer.addPathPrefix("/api",
HandlerTypePredicate.forAnnotation(RestController.class));
}
}
Now all the #RestControllers will have /api as the prefix path alongside the path configured.
Official Documentation
There's a new solution to solve this kind of problem available since Spring Boot 1.4.0.RC1 (Details see https://github.com/spring-projects/spring-boot/issues/5004)
The solution of Shahin ASkari disables parts of the Auto configuration, so might cause other problems.
The following solution takes his idea and integrates it properly into spring boot. For my case I wanted all RestControllers with the base path api, but still serve static content with the root path (f.e. angular webapp)
Edit: I summed it up in a blog post with a slightly improved version see https://mhdevelopment.wordpress.com/2016/10/03/spring-restcontroller-specific-basepath/
#Configuration
public class WebConfig {
#Bean
public WebMvcRegistrationsAdapter webMvcRegistrationsHandlerMapping() {
return new WebMvcRegistrationsAdapter() {
#Override
public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
return new RequestMappingHandlerMapping() {
private final static String API_BASE_PATH = "api";
#Override
protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
Class<?> beanType = method.getDeclaringClass();
RestController restApiController = beanType.getAnnotation(RestController.class);
if (restApiController != null) {
PatternsRequestCondition apiPattern = new PatternsRequestCondition(API_BASE_PATH)
.combine(mapping.getPatternsCondition());
mapping = new RequestMappingInfo(mapping.getName(), apiPattern,
mapping.getMethodsCondition(), mapping.getParamsCondition(),
mapping.getHeadersCondition(), mapping.getConsumesCondition(),
mapping.getProducesCondition(), mapping.getCustomCondition());
}
super.registerHandlerMethod(handler, method, mapping);
}
};
}
};
}
}
Also You can achieve the same result by configuring WebMVC like this:
#Configuration
public class PluginConfig implements WebMvcConfigurer {
public static final String PREFIX = "/myprefix";
#Override
public void configurePathMatch(PathMatchConfigurer configurer) {
configurer.addPathPrefix(PREFIX, c -> c.isAnnotationPresent(MyCustomAnnotation.class));
}
}
Implement WebMvcConfigurer on any #Configuration class.
Override configurePathMatch method.
You can do many useful things with PathMatchConfigurer e.g. add prefix for several classes, that satisfy predicate conditions.
I had the same concern and was not a fan of the Spring EL option due to the issues documented and I wanted the prefix to be tightly controlled in the controllers but I did not want to depend on the developers doing the right thing.
There might be a better way these days but this is what I did. Can you guys see any downsides, I am still in the process of testing any side-effects.
Define a custom annotation.
This allows a developer to explicitly provide typed attributes such as int apiVersion(), String resourceName(). These values would be the basis of the prefix later.
Annotated rest controllers with this new annotation
Implemented a custom RequestMappingHandlerMapping
In the RequestMappingHandlerMapping, I could read the attribute of the custom annotation and modify the final RequestMappingInfo as I needed. Here are a few code snippets:
#Configuration
public class MyWebMvcConfigurationSupport extends WebMvcConfigurationSupport {
#Bean
public RequestMappingHandlerMapping requestMappingHandlerMapping() {
return new MyCustomRequestMappingHandlerMapping();
}
}
And in the MyCustomRequestMappingHandlerMapping, overwrite the registerHandlerMethod:
private class MyCustomRequestMappingHandlerMapping extends RequestMappingHandlerMapping {
private Logger myLogger = LoggerFactory.getLogger(MyCustomRequestMappingHandlerMapping.class);
public MyCustomRequestMappingHandlerMapping() {
super();
}
#Override
protected void registerHandlerMethod(Object handler, Method method, RequestMappingInfo mapping) {
// find the class declaring this method
Class<?> beanType = method.getDeclaringClass();
// check for the My rest controller annotation
MyRestController myRestAnnotation = beanType.getAnnotation(MyRestController.class);
if (myRestAnnotation != null) {
// this is a My annotated rest service, lets modify the URL mapping
PatternsRequestCondition oldPattern = mapping.getPatternsCondition();
// create a pattern such as /api/v${apiVersion}/${resourceName}
String urlPattern = String.format("/api/v%d/%s",
myRestAnnotation.apiVersion(),
myRestAnnotation.resourceName());
// create a new condition
PatternsRequestCondition apiPattern =
new PatternsRequestCondition(urlPattern);
// ask our condition to be the core, but import all settinsg from the old
// pattern
PatternsRequestCondition updatedFinalPattern = apiPattern.combine(oldPattern);
myLogger.info("re-writing mapping for {}, myRestAnnotation={}, original={}, final={}",
beanType, myRestAnnotation, oldPattern, updatedFinalPattern);
mapping = new RequestMappingInfo(
mapping.getName(),
updatedFinalPattern,
mapping.getMethodsCondition(),
mapping.getParamsCondition(),
mapping.getHeadersCondition(),
mapping.getConsumesCondition(),
mapping.getProducesCondition(),
mapping.getCustomCondition()
);
}
super.registerHandlerMethod(handler, method, mapping);
}
}
Slightly less verbose solution which doesn't duplicate the logic of checking the annotation, but only changes the mapping path:
private static final String API_PREFIX = "api";
#Bean
WebMvcRegistrationsAdapter restPrefixAppender() {
return new WebMvcRegistrationsAdapter() {
#Override
public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
return new RequestMappingHandlerMapping() {
#Override
protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {
RequestMappingInfo mappingForMethod = super.getMappingForMethod(method, handlerType);
if (mappingForMethod != null) {
return RequestMappingInfo.paths(API_PREFIX).build().combine(mappingForMethod);
} else {
return null;
}
}
};
}
};
}
Side effects
Your error controller will also be mapped under /api/error, which breaks error handling (DispatcherServlet will still redirect errors to /error without prefix!).
Possible solution is to skip /error path when adding /api prefix in the code above (one more "if").
Someone has filed an issue in the Spring MVC Jira and come up with a nice solution, which I am now using. The idea is to use the Spring Expression Language in the prefix placed in each RestController file and to refer to a single property in the Spring Boot application.properties file.
Here is the link of the issue: https://jira.spring.io/browse/SPR-13882