You know the dependencies of some microservice from Configuration (if you uses centralized configuration).
According to the image: As you can see, this .yml file (starting with ms-port) of configuration with multiple dependencies to other microservices.
According to the Example The urlRecapcha is pointing to microservices ms-recaptcha.
But, How is it possible to know which microservices consume a certain microservice?
How the dependency know its consumers?
How the microservices ms-recaptcha knows that ms-port is its consumer?
Is it possible?
You can use Consumer Driven Contract approach (e.g. via Spring Cloud Contract - I'm a maintainer of that project, that's why I mention it but you can use other ones like Pact), where you store the information about which application uses which and you can generate tests out of it. You can check this part of the documentation of the Spring Cloud Contract project https://docs.spring.io/spring-cloud-contract/docs/3.1.4/reference/html/howto.html#how-to-common-repo-with-contracts that describes how you can create such a centralized repository that contains all the contracts for your company.
Related
There are web applications - WebAppA and WebAppB. Each web application depend on a Postgres database. We want to ship these applications to a customer who will deploy the applications on its own k8s cluster.
We want to create three packages - "WebappA", "WebAppB" and "Datastore". The webapp itself made of multiple services, not mentioning for the sake of simplicity.
We want to provide apt-get/brew/yum kind of experience, so that customer can deploy one or both the applications like al-carte. Most importantly while deploying, it should identify if the common package "DataStore" is running and not spin off yet another Postgres instance.
Is there any to package applications as packages for Kubernetes which can make installation easy with dependency handling?
Of course! One way to start would be using Helm charts. You can read more about them here.
Helm defines dependency relationships declaratively using charts, allows you to manipulate/maintain dependencies simply by managing some YAML manifests. It also allows you to have personalised repositories where you can put your images to be fetched from. It's really nice.
I have a Spring cloud stream application which I need to make an integration test for (to be specific using cucumber). The application communicate with other services using Kafka message broker. From what I know I could make this work using either a kafka testcontainers or using spring provided embedded kafka. But what I don't know is which one would be the best solution so are there anything that the testcontainer could do but embedded can't or the other way around? (use cases or example would be appreciate!)
p.s This integration should be able to run on ci/cd pipeline.
It is called embedded for a reason. It really can be only accessed from the process which spawned it. With Testcontainers you really can reuse existing container and have access to it from the other process. But that's probably to exotic.
I guess with properly configured Testcontainers you can reach as much as possible similarities with the prod you'd deploy your solution. The embedded Kafka might be limited in some areas, e.g. SSL configuration or so.
My project has a lot of Spring Batch Jobs.
I have requirement to create externalized configuration for message brokers (example Kafka, rabbitMQ etc.).
I want to use spring cloud stream since it has various binders to solve this problem.
Hence i wanted to understand if there is an integration between the two frameworks, please explain.
Our application environment in Websphere Application Server has 3 clusters
1. UI Cluster
2. Service Cluster
3. Integration Cluster
We have around 50 war files (Micro Services) deployed to Service cluster. All services are REST based and exposed through SPRING API. Restarting Service cluster takes close to 30 mins. This time is critical during live incidents in Production. For reasons, if Service cluster needs to be restarted, we need to have 30 mins downtime for all end users. We are looking to reduce to recycle time, please suggest us for any solution.
Is there a way to load all the Spring based jar files before the application starts?
i.e. for example there is a service war file called as xyz-1.0.war and there are Spring based jar files as maven dependencies. All 50 number of WAR files has the same set of dependencies, I am thinking in a way to see if we can load all the Spring based jars before the application is started by websphere server.
Please suggest.
I don't know that you can load them BEFORE the application starts (class loading is generally on-demand), but you might be able to speed things up through the use of shared libraries for your common files, so they'd be loaded by a single class loader rather than from each WAR's class loader. It won't eliminate the class loading activity, since each WAR would still need to load the necessary classes, but it'd speed up the mechanics of the class loads since the shared library loader would return the already-loaded class rather than searching its class path.
There are two different approaches you could take to this. Step one in both cases is to create a shared library with the classes that are shared among the applications. The options for step two:
1) Create a custom class loader on the server and associate the shared library with this new class loader. This will make the classes in the shared library visible to all applications running on the server.
2) In the shared library configuration, select "Use an isolated class loader for this shared library", then associate the shared library with any applications that require it. In the event that the shared classes are required only by some applications, this will provide them only to the applications that require them.
A couple points of caution:
If you require unique Class instances (for example, static values unique to each WAR), this approach won't work, because there will be only one instance of the Class loaded by the shared library loader. In that event, you'll have to stick with WAR-level packaging.
If you use the isolated class loader solution, note that those loaders use "parent last" class loading, in which they are searched before server class loaders. If you have anything in those libraries that conflicts with classes provided by the server, it could open you up to ClassCastExceptions or LinkageErrors.
Note that the shared library loaders operate as parents of the WAR loaders, and as such, classes in the libraries will not be able to "see" classes in the WARs. You'll need to make sure that the libraries are essentially self-contained in order for these approaches to be successful.
More specific details on the configuration steps can be found in this blog post: https://www.ibm.com/developerworks/community/blogs/aimsupport/entry/create_shared_library_and_associate_it_with_the_application_server_or_application_on_websphere_application_server?lang=en_us
If you are doing microservices then your services should be independently deployable, so they each should be in the separate cluster. Traditional WebSphere Application Server is a bit heavy weight for this solution (depending on how many resources you have on your nodes), so I'd suggest you to migrate your service cluster to WebSphere Liberty and in that case you could have each service in separate clusters. This would allow you to restart each service independently, at much shorter time.
If you are doing microservices, then your UI cluster should be prepared for any service unavailability - that is a primer when doing microservices, and display some message to end user, that this service is temporary unavailable.
Regarding your current setup - you could try the "Rollout update" option, which will restart your server sequentially, so services should be available on other nodes.
so-random-dude advice to use blue/green deployment is also very good. You could have 2 cells, and then switch plugin configuration after redeployment. If your services are written in a way that different versions can run in parallel during update, you would have no downtime.
If you want to reduce downtime further and improve performance, you should consider using Java EE/Rest services instead of Spring, as it will cut down significantly size of your app, amount of libs to be scanned, deployment and startup time. It is much better integrated and supported in WebSphere Liberty than tons of jars that you have to include with Spring.
I have a simple solution for you, just ditch the Websphere and deploy those 50 "wars" as independent jars with embedded netty/undertow/tomcat/jetty in it.
I am afraid, what you have currently is not at all a microservice architecture. Agreed, different teams/consultants/organizations has different interpretation of "micro"services. But this is an extreme, which you should avoid at any cost; because you are having all the pain points of microservice and ZERO benefits (benefits such as independent scalability/deployability etc).
Restarting Service cluster takes close to 30 mins. This time is
critical during live incidents in Production. For reasons, if Service
cluster needs to be restarted, we need to have 30 mins downtime for
all end users
Have you looked at different deployment strategies like Canary deployment / Blue-Green deployment? Do you have more than one instances behind a load balancer?
I am new to Jboss, want to know if micro services architecture is a right choice on JBOSS. I cannot change the application server as it is decided by client architect and I have no choice.
Want to know whether we can develop micro services with underlying JBOSS application server.
I understand Spring boot comes with embedded tomcat container, which makes it flexible to stop and start, deploy individual service with no impact to other services.
However will that architecture works with JBoss too.
Please suggest.
Thanks,
I actually developed a feasibility study to investigate the solution you mentioned. My conclusion is that it is totally viable to use Micro Service principles in a JBoss Platform.
I used the combination of JBoss \ Spring Boot \ Netflix to create successful Micro Service stack, I personally do that to find a solution to the transaction problem (multiple micro services collaborating) and the fan out problem which caused because excessive Network communication and Serialization costs.
I also wrote a blog about the subject, you might find more details there if you like to, here is the link.
Micro Services – Fan Out, Transaction Problems and Solutions with Spring Boot/JBoss and Netflix Eureka
By the definition what micro services are, then conceptually yes. A micro service is a service that is an independent unit, it could deployed, updated, and undeployed independently without affecting any unrelated part of your application. So that would mean having multiple instances of JBoss for MS and your application calling them through some sort of gateway or any other mechanism depending on your use case. If you plan to deploy all your MS in the same JBoss instance then it defeats the very purpose of a MS. Given that, JBoss wouldn't be a right choice for MS deployment because it will only make your MS deployment infrastructure quite heavy.
Depending on what your client's requirements are, your could possibly keep your webapp in JBoss and deploy your MS containers separately.
It depends on what you want to get out of microservices.
Some of the developers at my organisation looked at Spring Boot but concluded that it's best off being run as a standalone container rather than in JBoss, otherwise you've effectively got two container frameworks competing (SB and JBoss) and a range of associated issues.
Deploying microservices in JBoss won't give you the same flexibility as a true container system like Docker. With Docker you create standalone packages for your microservices that contain all the code, system tools, runtime environment, etc. It can be as small or large as it needs to be. JBoss on the other hand is a large container running a single JVM designed to hold multiple applications. The level of isolation is not the same, and it's not efficient to have JBoss as a container for a single microservice so you have to appropriately size and then deploy to the instance to make use of the resources it has available.
If you're looking at microservices as a way to gain greater control over service lifecycle management (deployment, versioning, deprecating, etc.) as opposed to an automated, web-scale component deployment model a la Netflix or LinkedIn, you could do this adequately with JBoss.
I'm actually looking to do something along these lines here. It won't be true microservices but by packaging and deploying individual, properly versioned APIs rather than monolithic applications and following most of the other principles of microservice development (componentisation, business function focus, stateless etc.) we will be hopefully better able to manage and benefit from our APIs.
Our APIs will all be behind an API gateway and load balancer so we can choose how we distribute the microserves distributed across the JBoss instances and balance resource usage as required. Note that our organisation is relatively small and has relatively low and predictable traffic so this approach should work fine. Your needs however may be different.