Spring boot - Adding data read only - java

I am thinking what would be best solution for following case. Suppose we have at start CRUD app - using Spring Boot. I would like to add read only state for this application - which allows only data read and blocks create, update, delete data operations for admin role. I think about adding aspect (#Aspect) which checks current app state (which is saved in db) and starts if create, update, update operations are invoked. If app is in read-only state - exception will be thrown (handled by #ControllerAdvice)
I wonder if adding aspect is the best option - I dont want modify existing code. Whats your take on that? Moreover - how would you write integration tests for #aspect - testing if aspect starts properly? How could be aspects tested for this case? What are good practises for testing #aspects (integration tests #springboottest)

This honestly seems like an inconvenient way of doing this. Why not just add an Interceptor that checks for this? I did something similar before
#Component
#RequiredArgsConstructor
public class ReadOnlyModeInterceptor implements HandlerInterceptor {
private final ServerProperties serverProperties;
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
if (serverProperties.isReadOnlyMode()) {
String method = request.getMethod();
boolean isReadOnlyMethod = "GET".equals(method) || "OPTIONS".equals(method);
String servletPath = request.getServletPath();
boolean isReadOnlyPath = isReadOnlyPath(servletPath);
if (!isReadOnlyMethod && isReadOnlyPath) {
throw new ServiceUnavailableException("Server is in read-only mode.");
}
}
return true;
}
private boolean isReadOnlyPath(String servletPath) {
if (serverProperties.isFullyReadOnly()) {
return true; // wildcard option, entire server is read-only
}
return serverProperties.getReadOnlyPaths().stream().anyMatch(servletPath::contains);
}
}
You also need to register it
#RequiredArgsConstructor
#Configuration
public class WebMvcConfig implements WebMvcConfigurer {
private final ReadOnlyModeInterceptor readOnlyModeInterceptor;
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(readOnlyModeInterceptor).order(0);
}
}

Related

Spring boot + Caffeine cache + Check header

i'm trying to use cache (caffeine) with Spring boot and im having a problem. I need to check the header "header-name" in every call but application is caching it so after first request with the right header, dont matter what header i send and the application will not check it and is just returning data from the cache, is there anyway that i can force spring to check header and then get data from cache?
#GetMapping("/request-a")
#Cacheable(cacheNames = "cachename", key = "#root.methodName")
public ResponseEntity<?> makeRequest(#RequestHeader("header-name") String headerName) {
this.authConfig.headerCheck(headerName);
/*
code
*/
}
I already used header "Cache-Control:no-cache" and didnt resolve my problem.
Thanks in advance.
Edit1: method "headerCheck" just check if its equal to another String or not null.
Found a solution:
Create a classe that implements HandlerInterceptor and use preHandle method.
#Component
public class CheckHeaderInterceptor implements HandlerInterceptor {
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
// validate what you want, on error return false
// if everything its ok, return true
}
}
Then register the handler with:
public class WebMvcConfig implements WebMvcConfigurer {
#Autowired
private CheckHeaderInterceptor interceptor;
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(interceptor).addPathPatterns("url that you wannna use handler");
}
}

How to add SynchronizationCallbacks to #TransactionalEventListener during spring boot application startup?

I have a spring boot application that uses a few #TransactionalEventListener(phase = TransactionPhase.AFTER_COMMIT). I noticed that spring boot doesn't do any exception logging for them when they end up with an exception being thrown.
Because of this I wanted to add some generic logging facility for such exceptions. I found that TransactionalApplicationListener.SynchronizationCallback is the interface I need to implement. However it seems complicated to register these callbacks. I didn't find any call of TransactionalApplicationListener#addCallback in the spring dependencies that would achieve this.
Trying to get a list of TransactionalApplicationListener and the SynchronizationCallback injected and then call addCallback in a #PostConstruct didn't get me further because there were always no listeners injected even though the application did make successful use of them.
So how do I add SynchronizationCallbacks to TransactionalApplicationListeners during spring boot application startup?
The first thing to note is that TransactionalApplicationListeners like all ApplicationListener are not beans in the spring context. They live somewhat outside of it (see org.springframework.context.ConfigurableApplicationContext#addApplicationListener). So injecting them is not possible for the application context.
While debugging and looking through spring sources one finds that these listeners are being created by org.springframework.transaction.event.TransactionalEventListenerFactory. And that is where my solution steps into. We decorate that factory with another one that is aware of SynchronizationCallbacks:
public class SynchronizationCallbackAwareFactory implements EventListenerFactory, Ordered {
private final TransactionalEventListenerFactory delegate;
private final Provider<List<SynchronizationCallback>> synchronizationCallbacks;
private final int order;
public SynchronizationCallbackAwareFactory(TransactionalEventListenerFactory transactionalEventListenerFactory,
Provider<List<SynchronizationCallback>> synchronizationCallbacks,
int order) {
this.delegate = transactionalEventListenerFactory;
this.synchronizationCallbacks = synchronizationCallbacks;
this.order = order;
}
#Override
public boolean supportsMethod(Method method) {
return delegate.supportsMethod(method);
}
#Override
public ApplicationListener<?> createApplicationListener(String beanName, Class<?> type, Method method) {
ApplicationListener<?> applicationListener = delegate.createApplicationListener(beanName, type, method);
if (applicationListener instanceof TransactionalApplicationListener) {
TransactionalApplicationListener<?> listener = (TransactionalApplicationListener<?>) applicationListener;
Collection<SynchronizationCallback> callbacks = this.synchronizationCallbacks.get();
callbacks.forEach(listener::addCallback);
}
return applicationListener;
}
#Override
public int getOrder() {
return order;
}
}
Note that I use a javax.inject.Provider in my case to make the retrieval of the callbacks at the latest possible time.
The decorator has to be Ordered because spring will use the first factory supporting the method it gets across. And therefore the order of an instance of this class has to have higher precedence as the order value 50 of TransactionEventListenerFactory.
I had simmilar problem with code as below
#Transactional(propagation = Propagation.REQUIRES_NEW)
public class SomeListenerFacade {
#TransactionalEventListener
public void onSomething(SomeEvent event) {
throw new RuntimeException("some cause");
}
}
I followed your solution. It worked. On the way I've found an alternative way for at least seeing that exception in the logfile
# application.properties
logging.level.org.springframework.transaction.support.TransactionSynchronizationUtils = DEBUG

Calling Spring controller method without going to internet

tldr: Is there a way to make an internal request (using the method's path) without going to the internet?
--
Why do I need it? I have a project which receives many events. The decision of who will handle each event is made by a Controller. So I have something similar to this:
#RestController
#RequestMapping("/events")
public class EventHandlerAPI {
#Autowired
private EventAHandler eventAhandler;
#Autowired
private EventBHandler eventBhandler;
#PostMapping("/a")
public void handleEventA(#RequestBody EventA event) {
eventAhandler.handle(id, event);
}
#PostMapping("/b")
public void handleEventB(#RequestBody EventB event) {
eventBhandler.handle(id, event);
}
}
We recently added support to receive events through a Queue service. It sends to us the payload and the event class. Our decision is to let both interfaces working (rest and queue). The solution to avoid code duplication was to keep the Controller choosing which handler will take care of the event. The code nowadays is similar to this:
#Configuration
public class EventHandlerQueueConsumer {
#Autowired
private EventHandlerAPI eventHandlerAPI;
private Map<Class, EventHandler> eventHandlers;
#PostConstruct
public void init() {
/* start listen queue */
declareEventHandlers();
}
private void declareEventHandlers() {
eventHandlers = new HashMap<>();
eventHandlers.put(EventAHandler.class, (EventHandler<EventAHandler>) eventHandlerAPI::handleEventA);
eventHandlers.put(EventBHandler.class, (EventHandler<EventBHandler>) eventHandlerAPI::handleEventB);
}
private void onEventReceived(AbstractEvent event) {
EventHandler eventHandler = eventHandlers.get(event.getClass());
eventHandler.handle(event);
}
private interface EventHandler<T extends AbstractEvent> {
void handle(T event);
}
}
This code works, but it doesn't let the controller choose who will handle the event (our intention). The decision is actually being made by the map.
What I would like to do was to invoke the controller method through it's request mapping without going to the internet. Something like this:
#Configuration
public class EventHandlerQueueConsumer {
// MADE UP CLASS TO SHOW WHAT I WANT
#Autowired
private ControllerInkover controllerInvoker;
#PostConstruct
public void init() { /* start listen queue */ }
private void onEventReceived(AbstractEvent event) {
controllerInvoker.post(event.getPath(), new Object[] { event });
}
}
This way is much cleaner and let all the decisions be made by the controller.
I've researched a lot and didn't found a way to implement it. Debugging spring, I found how he routes the request after the DispatcherServlet, but all the spring internals uses HttpServletRequest and HttpServletResponse :(
Is there a way to make an internal request (using the method's path) without going to the internet?
They are classes of the same application
Then it should easy enough.
1) You can call your own API on http(s)://localhost:{port}/api/{path} using RestTemplate utility class. This is preferred way, since you'll follow standard MVC pattern. Something like:
restTemplate.exchange(uri, HttpMethod.POST, httpEntity, ResponseClass.class);
2) If you don't want to invoke network connection at all, then you can either use Spring's internal to find the mapping/method map or use some reflection to build custom
map upon controller's startup. Then you can pass your event/object to the method from the map in a way shown in your mock-up class. Something like:
#RequestMapping("foo")
public void fooMethod() {
System.out.println("mapping = " + getMapping("fooMethod")); // you can get all methods/mapping in #PostContruct initialization phase
}
private String getMapping(String methodName) {
Method methods[] = this.getClass().getMethods();
for (int i = 0; i < methods.length; i++) {
if (methods[i].getName() == methodName) {
String mapping[] = methods[i].getAnnotation(RequestMapping.class).value();
if (mapping.length > 0) {
return mapping[mapping.length - 1];
}
}
}
return null;
}

Best practice to 'rollback' REST method calls inside method

The title might be incorrect, but I will try to explain my issue. My project is a Spring Boot project. I have services which do calls to external REST endpoints.
I have a service method which contains several method calls to other services I have. Every individual method call can be successful or not. Every method call is done to a REST endpoint and there can be issues that for example the webservice is not available or that it throws an unknown exception in rare cases. What ever happens, I need to be able to track which method calls were successful and if any one of them fails, I want to rollback to the original state as if nothing happened, see it a bit as #Transactional annotation. All REST calls are different endpoints and need to be called separately and are from an external party which I don't have influence on. Example:
public MyServiceImpl implements MyService {
#Autowired
private Process1Service;
#Autowired
private Process2Service;
#Autowired
private Process3Service;
#Autowired
private Process4Service;
public void bundledProcess() {
process1Service.createFileRESTcall();
process2Service.addFilePermissionsRESTcall();
process3Service.addFileMetadataRESTcall(); <-- might fail for example
process4Service.addFileTimestampRESTcall();
}
}
If for example process3Service.addFileMetadataRESTcall fails I want to do something like undo (in reverse order) for every step before process3:
process2Service.removeFilePermissionsRESTcall();
process1Service.deleteFileRESTcall();
I read about the Command pattern, but that seems to be used for Undo actions inside an application as a sort of history of actions performed, not inside a Spring web application. Is this correct for my use case too or should I track per method/webservice call if it was successful? Is there a best practice for doing this?
I guess however I track it, I need to know which method call failed and from there on perform my 'undo' method REST calls. Although in theory even these calls might also fail of course.
My main goal is to not have files being created (in my example) which any further processes have not been performed on. It should either be all successful or nothing. A sort of transactional.
Update1: improved pseudo implementation based on comments:
public Process1ServiceImpl implements Process1Service {
public void createFileRESTcall() throws MyException {
// Call an external REST api, pseudo code:
if (REST-call fails) {
throw new MyException("External REST api failed");
}
}
}
public class BundledProcessEvent {
private boolean createFileSuccess;
private boolean addFilePermissionsSuccess;
private boolean addFileMetadataSuccess;
private boolean addFileTimestampSuccess;
// Getters and setters
}
public MyServiceImpl implements MyService {
#Autowired
private Process1Service;
#Autowired
private Process2Service;
#Autowired
private Process3Service;
#Autowired
private Process4Service;
#Autowired
private ApplicationEventPublisher applicationEventPublisher;
#Transactional(rollbackOn = MyException.class)
public void bundledProcess() {
BundleProcessEvent bundleProcessEvent = new BundleProcessEvent();
this.applicationEventPublisher.publishEvent(bundleProcessEvent);
bundleProcessEvent.setCreateFileSuccess = bundprocess1Service.createFileRESTcall();
bundleProcessEvent.setAddFilePermissionsSuccess = process2Service.addFilePermissionsRESTcall();
bundleProcessEvent.setAddFileMetadataSuccess = process3Service.addFileMetadataRESTcall();
bundleProcessEvent.setAddFileTimestampSuccess = process4Service.addFileTimestampRESTcall();
}
#TransactionalEventListener(phase = TransactionPhase.AFTER_ROLLBACK)
public void rollback(BundleProcessEvent bundleProcessEvent) {
// If the last process event is successful, we should not
// be in this rollback method even
//if (bundleProcessEvent.isAddFileTimestampSuccess()) {
// remove timestamp
//}
if (bundleProcessEvent.isAddFileMetadataSuccess()) {
// remove metadata
}
if (bundleProcessEvent.isAddFilePermissionsSuccess()) {
// remove file permissions
}
if (bundleProcessEvent.isCreateFileSuccess()) {
// remove file
}
}
Your operation looks like a transaction, so you can use #Transactional annotation. From your code I can't really tell how you are managing HTTP response calls for each of those operations, but you should consider having your service methods to return them, and then do a rollback depending on response calls. You can create an array of methods like so, but how exactly you want your logic to be is up to you.
private Process[] restCalls = new Process[] {
new Process() { public void call() { process1Service.createFileRESTcall(); } },
new Process() { public void call() { process2Service.addFilePermissionsRESTcall(); } },
new Process() { public void call() { process3Service.addFileMetadataRESTcall(); } },
new Process() { public void call() { process4Service.addFileTimestampRESTcall(); } },
};
interface Process {
void call();
}
#Transactional(rollbackOn = Exception.class)
public void bundledProcess() {
restCalls[0].call();
... // say, see which process returned wrong response code
}
#TransactionalEventListener(phase = TransactionPhase.AFTER_ROLLBACK)
public void rollback() {
// handle rollback according to failed method index
}
Check this article. Might come in handy.
The answer to this question is quite broad. There are various ways to do distributed transactions to go through them all here. However, since you are using Java and Spring, your best bet is to use something like JTA (Java Transaction API), which enables a distributed transactions across multiple services/instances/etc.. Fortunately, Spring Boot supports JTA using either Atomikos or Bitronix. You can read the doc here.
One approach to enable distributed transactions is through a message broker such as JMS, RabbitMQ, Kafka, ActiveMQ, etc. and use a protocol like XA transactions (two-phase commit). In the case of external services that do not support distributed, one approach is to write a wrapper service that understands XA transactions to that external service.

Spring: Read property from file why executing Condition::match

I want to implement a conditional Bean depending on a flag in my application.properties. Example:
// application.properties
service=foobar
The idea is to make different service implementations configurable, let assume I got a central configuration class for this service in Spring:
#Configuration
#Import({ServiceA.class, ServiceB.class, ...})
public class ServiceConfiguration {
...
}
And possible service implementations would look like
#Configuration
public class ServiceA implements Condition {
#Bean
#Conditional(ServiceA.class)
public Service service() {
Service a = ...
return a;
}
#Override
public boolean matches(
ConditionContext conditionContext,
AnnotatedTypeMetadata annotatedTypeMetadata) {
// getProperty will alsways return null for some reason
return conditionContext
.getEnvironment()
.getProperty("service")
.equals("ServiceA");
}
// This will be null anyways
#Value("${service}")
private String confService;
}
Since the class implementing Condition (here just the same class ServiceA) will be initialized via default constructor #Value-injections won't work. How ever, by what I understand getProperty()should return the correct value. What am I doing wrong? How can I access application properties at this point?
I found at "dirty workarround", I really don't like that solution, how ever, it solves the problem. As mentioned here a #PropertySource fixes the problem (I haven't tried this before posting here since it wasn't an accpeted answer).
#Configuration
#PropertySource(value="file:config/application.properties")
public class ServiceA implements Condition {
#Bean
#Conditional(ServiceA.class)
public Service service() {
Service a = ...
return a;
}
#Override
public boolean matches(
ConditionContext conditionContext,
AnnotatedTypeMetadata annotatedTypeMetadata) {
// Will work now
return conditionContext
.getEnvironment()
.getProperty("service")
.equals("ServiceA");
}
}
Although this works I don't like it for several reason:
With every implementation I have code redundancy (giving a path to a config file)
It's highly unmaintainable when having multiple configuration files
Example: Behavior like load default.properties <-then load and overwrite with -> customer.properties won't work anymore (altough this should be solvable using #PropertySources which would, on the other hand, increase code redundancy)

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