Spring cloud config client helps to change the properties in run time. Below are 2 ways to do that
Update GIT repository and hit /refresh in the client application to get the latest values
Update the client directly by posting the update to /env and then /refresh
Problem here in both the approaches is that there could be multiple instances of client application running in cloud foundry and above rest calls will reach any one of the instances leaving application in inconsistent state
Eg. POST to /env could hit instance 1 and leaves instance 2 with old data.
One solution I could think of is to continuously hit these end points "n" times using for loop just to make sure all instance will be updated but it is a crude solution. Do any body have better solution for this?
Note: We are deploying our application in private PCF environment.
The canonical solution for that problem is the Spring Cloud Bus. If your apps are bound to a RabbitMQ service and they have the bus on the classpath there will be additional endpoints /bus/env and /bus/refresh that broadcast the messages to all instances. See docs for more details.
Spring Cloud Config Server Not Refreshing
see org.springframework.cloud.bootstrap.config.RefreshEndpoint code hereļ¼
public synchronized String[] refresh() {
Map<String, Object> before = extract(context.getEnvironment()
.getPropertySources());
addConfigFilesToEnvironment();
Set<String> keys = changes(before,
extract(context.getEnvironment().getPropertySources())).keySet();
scope.refreshAll();
if (keys.isEmpty()) {
return new String[0];
}
context.publishEvent(new EnvironmentChangeEvent(keys));
return keys.toArray(new String[keys.size()]);
}
that means /refresh endpoint pull git first and then refresh catch,and public a environmentChangeEvent,so we can customer the code like this.
Related
I have an external requirement that I provide an endpoint to tell the load balancer to send traffic to my app. Much like the Kubernetes "readiness" probe, but it has to be a certain format and path, so I can just give them the actuator health endpoint.
In the past I've used the HealthEndpoint and called health(), but that doesn't work for reactive apps. Is there a more flexible way to see if the app is "UP"? At this level I don't care if it's reactive or servlet, I just want to know what Spring Boot says about the app.
I haven't found anything like this, most articles talk about calling /actuator/health, but that isn't what I need.
Edit:
Just a bit more detail, I have to return a certain string "NS_ENABLE" if it's good. There are certain conditions where I return "NS_DISABLE", so I can't just not return anything, which would normally make sense.
Also, I really like how Spring Boot does the checking for me. I'd rather not re-implement all those checks.
Edit 2: My final solution
The answers below got me very far along even though it wasn't my final solution, so I wanted to give a hint to my final understanding.
It turns out that the HealthEndpoint works for reactive apps just as well as servlet apps, you just have to wrap them in Mono.
How do we define health of any web servers?
We look at how our dependent services are, we check the status of Redis, MySQL, MongoDB, ElasticSearch, and other databases, this's what actuator does internally.
Actuator checks the status of different databases and based on that it returns Up/Down.
You can implement your own methods that would check the health of dependent services.
Redis is healthy or not can be checked using ping command
MySQL can be verified using SELECT 1 command or run some query that should always success like SHOW TABLES
Similarly, you can implement a health check for other services. If you find all required services are up then you can declare up otherwise down.
What about shutdown triggers? Whenever your server receives a shutdown signal than no matter what's the state of your dependent services, you should always say down, so that upstream won't send a call to this instance.
Edit
The health of the entire spring app can be checked programmatically by autowiring one or more beans from the Actuator module.
#Controller
public class MyHealthController{
#Autowired private HealthEndpoint healthEndpoint;
#GetMapping("health")
public Health health() {
Health health = healthEndpoint.health();
return healthEndpoint.health();
}
}
There're other beans related to health check, we can auto wire required beans. Some of the beans provide the health of the respective component, we can combine the health of each component using HealthAggregator to get the final Health. All registered health indicator components can be accessed via HealthIndicatorRegistry.
#Controller
public class MyHealthController{
#Autowired private HealthAggregator healthAggregator;
#Autowired private HealthIndicatorRegistry healthIndicatorRegistry;
#GetMapping("health")
public Health health() {
Map<String, Health> health = new HashMap<>();
for (Entry<String, HealthIndicator> entry : healthIndicatorRegistry.getAll().entrySet()) {
health.put(entry.getKey(), entry.getValue().health());
}
return healthAggregator.aggregate(health);
}
}
NOTE: Reactive component has its own health indicator. Useful classes are ReactiveHealthIndicatorRegistry, ReactiveHealthIndicator etc
Simple solution is to write your own health endpoint instead of depending on Spring.
Spring Boot provides you production-ready endpoints but if it doesn't satisfy your purpose, write your end-point. It will just return "UP" in response. If the service is down, it will not return anything.
Here's the spring boot documentation on writing reactive health endpoints. Folow the guide and should be enough for your usecase.
They also document on how to write liveliness and Readiness of your application.
https://docs.spring.io/spring-boot/docs/current/reference/html/production-ready-features.html#reactive-health-indicators
I d like to make a REST call once on application startup to retrieve some configuration parameters.
For example, we need to retrieve an entity called FleetConfiguration from another server. I d like to do a GET once and save the keep the data in memory for the rest of the runtime.
What s the best way of doing this in Spring? using Bean, Config annotations ..?
I found this for example : https://stackoverflow.com/a/44923402/494659
I might as well use POJOs handle the lifecycle of it myself but I am sure there s a way to do it in Spring without re-inventing the wheel.
Thanks in advance.
The following method will run once the application starts, call the remote server and return a FleetConfiguration object which will be available throughout your app. The FleetConfiguration object will be a singleton and won't change.
#Bean
#EventListener(ApplicationReadyEvent.class)
public FleetConfiguration getFleetConfiguration(){
RestTemplate rest = new RestTemplate();
String url = "http://remoteserver/fleetConfiguration";
return rest.getForObject(url, FleetConfiguration.class);
}
The method should be declared in a #Configuration class or #Service class.
Ideally the call should test for the response code from the remote server and act accordingly.
Better approach is to use Spring Cloud Config to externalize every application's configuration here and it can be updated at runtime for any config change so no downtime either around same.
I am working on a project that has a requirement of Pivotal GemFire.
I am unable to find a proper tutorial about how to configure gemFire with Spring Boot.
I have created a partitioned Region and I want to configure Locators as well, but I need only server-side configuration as client is handled by someone else.
I am totally new to Pivotal GemFire and really confused. I have tried creating a cache.xml but then somehow a cache.out.xml gets created and there are many issues.
#Priyanka-
Best place to start is with the Guides on spring.io. Specifically, have a look at...
"Accessing Data with GemFire"
There is also...
"Cache Data with GemFire", and...
"Accessing GemFire Data with REST"
However, these guides focus mostly on "client-side" application concerns, "data access" (over REST), "caching", etc.
Still, you can use Spring Data GemFire (in a Spring Boot application even) to configure a GemFire Server. I have many examples of this. One in particular...
"Spring Boot GemFire Server Example"
This example demonstrates how to bootstrap a Spring Boot application as a GemFire Server (technically, a peer node in the cluster). Additionally, the GemFire properties are specified Spring config and can use Spring's normal conventions (property placeholders, SpEL expression) to configure these properties, like so...
https://github.com/jxblum/spring-boot-gemfire-server-example/blob/master/src/main/java/org/example/SpringBootGemFireServer.java#L59-L84
This particular configuration makes the GemFire Server a "GemFire Manager", possibly with an embedded "Locator" (indicated by the start-locator GemFie property, not to be confused with the "locators" GemFire property which allows our node to join and "existing" cluster) as well as a GemFire CacheServer to serve GemFire cache clients (with a ClientCache).
This example creates a "Factorials" Region, with a CacheLoader (definition here) to populate the "Factorials" Region on cache misses.
Since this example starts an embedded GemFire Manager in the Spring Boot GemFire Server application process, you can even connect to it using Gfsh, like so...
gfsh> connect --jmx-manager=localhost[1099]
Then you can run "gets" on the "Factorial" Region to see it compute factorials of the numeric keys you give it.
To see more advanced configuration, have a look at my other repos, in particular the Contacts Application RI (here).
Hope this helps!
-John
Well, I had the same problem, let me share with you what worked for me, in this case I'm using Spring Boot and Pivotal GemFire as cache client.
Install and run GemFire
Read the 15 minutes quick start guide
Create a locator(let's call it locator1) and a server(server1) and a region(region1)
Go to the folder where you started the 'Gee Fish'(gfsh) and then go to the locator's folder and open the log file, in that file you can get the port your locator is using.
Now let's see the Spring boot side:
In you Application with the main method add the #EnablegemFireCaching annotation
In the method(wherever it is) you want to cache, add the #Cacheable("region1") annotation.
Now let's create a configuration file for the caching:
//this is my working class
#Configuration
public class CacheConfiguration {
#Bean
ClientCacheFactoryBean gemfireCacheClient() {
return new ClientCacheFactoryBean();
}
#Bean(name = GemfireConstants.DEFAULT_GEMFIRE_POOL_NAME)
PoolFactoryBean gemfirePool() {
PoolFactoryBean gemfirePool = new PoolFactoryBean();
gemfirePool.addLocators(Collections.singletonList(new ConnectionEndpoint("localhost", HERE_GOES_THE_PORT_NUMBER_FROM_STEP_4)));
gemfirePool.setName(GemfireConstants.DEFAULT_GEMFIRE_POOL_NAME);
gemfirePool.setKeepAlive(false);
gemfirePool.setPingInterval(TimeUnit.SECONDS.toMillis(5));
gemfirePool.setRetryAttempts(1);
gemfirePool.setSubscriptionEnabled(true);
gemfirePool.setThreadLocalConnections(false);
return gemfirePool;
}
#Bean
ClientRegionFactoryBean<Long, Long> getRegion(ClientCache gemfireCache, Pool gemfirePool) {
ClientRegionFactoryBean<Long, Long> region = new ClientRegionFactoryBean<>();
region.setName("region1");
region.setLookupEnabled(true);
region.setCache(gemfireCache);
region.setPool(gemfirePool);
region.setShortcut(ClientRegionShortcut.PROXY);
return region;
}
That's all!, also do not forget to serialize(implements Serializable) the class is being cached(The class your cached method is returning)
So I already success implement SSO using spring session and redis on development localhost domain.
But when I deploy to server using two sub domain.
login.example.com
apps.example.com
They always create new session Id on each sub domain.
I already try to configure using Context in tomcat configuration.
<Context sessionCookieDomain=".example.com" sessionCookiePath="/">
But no luck.
Spring session moves the session management on application level, so no surprise that trying to configure the container (in your case tomcat) has no effect. Currently there is a TODO in spring-session code to allow setting the domain, but is not implemented.
Maybe it is best to open an issue to allow setting the domain or comment/vote on https://github.com/spring-projects/spring-session/issues/112.
Meanwhile a workaround would be to go with your own implementation of MultiHttpSessionStrategy based on CookieHttpSessionStrategy.
Finally I succeeded to setdomain on application level.
You're right, I hope in the future they implement the feature to set domain.
For now I create CustomCookieHttpSessionStrategy for my own implmentation.
private Cookie createSessionCookie(HttpServletRequest request,
Map<String, String> sessionIds) {
...
sessionCookie.setDomain(".example.com");
// TODO set domain?
...
}
And then register bean as HttpSessionStrategy.
Is it possible to set a dynamic provider for a Marshalling web service outbound gateway?
I mean, if I try for example: http://100.0.0.1 and it not works, I would like to try http://100.0.0.2 instead
My current configuration:
MarshallingWebServiceOutboundGateway gw = new MarshallingWebServiceOutboundGateway(provider, jaxb2Marshaller(), jaxb2Marshaller());
Yes, that's true. Since MarshallingWebServiceOutboundGateway allows to inject DestinationProvider, you feel free to provide any custom implementation.
For your fault-tolerant use-case you should do: new URLConnection(url).connect() to test connection to the target server in that your DestinationProvider implementation.
UPDATE
But If I how can I test new URLConnection(url).connect() if I have https credentials, certificate or any kind of security
Well, another good solution from the Spring Integration is load-balancing and several subscribers to the same DirectChannel:
#Bean
public MessageChannel wsChannel() {
return new DirectChannel(null);
}
to switch of the default RoundRobinLoadBalancingStrategy.
And after that you can have several #ServiceActivator(inputChannel="wsChannel"). When the first one is fail, the message is sent to the second and so on, until the good result or the fall for each URL.