In spring cloud dataflow, as per my understanding each stream is a microservice but the dataflow server is not. Am I right?
Is it possible to have multiple instances of spring cloud dataflow(SCDF) server? How to loadbalance the dataflow server? I am planning to deploy it in AWS.The official documentation didn't mention anything about loadbalancing of dataflow server. If it is possible how do Dashboard, shell works?
The SCDF-server is a regular Spring MVC + Spring Boot application that serves the REST-APIs, DSL commands, UI, and repository access for stream/task metadata persistence.
In platforms like Cloud Foundry, Kubernetes and others, upon scaling the SCDF-server, the platform automatically handles traffic routing and load-balancing.
If you were to orchestrate the deployment on your own and on AWS, you'd have to plug a load-balancer in front of the server instances. The shell, UI, and REST-APIs would hit the load-balancer instead, to interact with the SCDF-server.
Related
I'm trying to understand why and when to use Spring Cloud K8s Discovery Server when K8s has a Native Service Discovery which does:
Service discovery
Ensures compatibility with additional tooling (e.g. Istio)
Isn't it simpler if your app can simply rely/use a DNS name of a service it needs? On top that that it gets load balancing as well. Why should one even think about a Discovery Server?
Can Spring Cloud Eureka get some of its properties from Spring Cloud Config with our microservices utilizing Discovery First Bootstrap? So, our Spring Cloud Config microservices start up and attempt to register with our Spring Cloud Eureka microservices so they can be discovered, while Spring Cloud Eureka microservices start up and attempt to get some of their configuration properties from the Spring Cloud Config microservices. This is the ideal scenario I'm trying to implement, but it makes sense to me that this would result in both sets of microservices waiting on each other, resulting in a deadlocked state. It's important to note that we have three Spring Cloud Eureka instances running as peers, giving us an HA configuration, as well as three Spring Cloud Config instances. With all eureka.* properties in the Spring Cloud Eureka bootstrap.yml, everything starts fine, and the peers are able to replicate with each other. However, as soon as I configure Spring Cloud Eureka to get its properties from Spring Cloud Config, each instance fails to connect to its peers.
So, my main question is whether or not this configuration even makes sense, and if so, where is the documentation that covers such a configuration?
Context
I am deploying a set of services that are containerised using Docker into AWS. No matter which deployment solution is chosen (e.g. raw EC2/ECS/Elastic Beanstalk/Fargate) we will face the issue of "service discovery".
To name just a few of the options for service discovery that I've considered:
AWS Route 53 Service Registry
Kubernetes
Hashicorp Consul
Spring Cloud Netflix Eureka
Specifics Of My Stack
I am developing Java Spring Boot applications using Spring Cloud with the target deployment environment being AWS.
Given that my stack is Spring based, spring cloud eureka made sense to me while developing locally. It was easy to set up a single node, integrates well with the stack and ecosystem of choice and required very little set up.
Locally, we are using docker compose (not swarm) to deploy services - one of the containers deployed is a single node Eureka service discovery server.
However, when we progress outside of local development and into staging or production environment we are considering options like Kubernetes.
My Own Assessment Of Pros/Cons
AWS Route 53 Service Registry
Requires us to couple code specifically to AWS services. Not a problem per se, we are quite tied in anyway on other parts of the stack (SNS/SQS).
Makes running the stack locally slightly more difficult as it relies on Route 53, I suppose we could open up a certain hosted zone for local development.
AWS native, no managing service registries or extra "moving parts".
Spring Cloud Eureka
Downside is that thus requires us to deploy and manage a high availability service registry cluster and requires more resources. Another "moving part" to manage.
Advantages are that it fits into our stack well (spring ecosystem, spring boot, spring cloud, feign and zuul work well with this). Also can be run locally trivially.
I presume we need to configure the networks and registry zone to ensure that that clients publish their host address rather and docker container internal IP address. e.g. if service A is on host A and wants to talk to service B on host B, service B needs to advertise its EC2 address rather than some internal docker IP.
Questions
If we use Kubernetes for orchestration, are there any disadvantages to using something like Spring Cloud Eureka over the built in service discovery options described here https://kubernetes.io/docs/concepts/services-networking/service/#discovering-services
Given Kube provides this, it seems suboptimal to then use eureka deployed using kube to perform discovery. I presume kube can make some optimisations that impact avaialbility and stability that might nit be possible using eureka. e.g kube would know when deploying a new service - eureka will have to rely on heartbeats/health checks and depending on how that is configured (e.g. frequency) this could result in stale records whereas i presume kube might not suffer from this for planned service shutdown/restarts. I guess it still does for unplanned failures such as a host failure or network partition.
Does anyone have any advice on this, do people use services like Kubernetes but use other mechanisms for service discovery rather than those provided by kube. Is there a good reason to do one or the other?
Possible Challenges I Anticipate
We could replace eureka, but relying on Kube to perform discovery will mean that we need to run kube locally to deploy whereas currently we have a simple tiny docker-compose file. Also, I'll have to look at how easy it'll be to ensure that ribbon, zuul and feign play nicely with this.
Currently we have ribbon configured with a eureka client so that service A can server to service B just as "service-b" for example and have ribbon resolve a healthy host via a eureka client. I guess we can configure ribbon to not use eureka and use an external Kube service name which will be resolved by Kube DNS at runtime...
Final Note
Thanks in advance for any contribution or advice. I know this might elicit a primarily opinion focused response. But I am hoping someone can provide objective guidance on when one solution might be preferable to another.
Service discovery is something you get out-of-the-box with Kubernetes. So having another external service in your platform will be another application to maintain, deploy and can be a point of failure. So I would stick with the the service discovery provided by Kubernetes.
Is it possible to create a dedicated service catalog for each project/namespaces in Openshift? I am hosting a multi-tenant OpensShift cluster. When each tenants login to OpenShift cluster, they should only be able see services which is relevant for them in the service catalog.
For eg: Tenant-A should only see MySQL and Apache services. Tenant-B should only see ElasticSearch and Ruby services. Is it possible to do this kind of isolation?
I am now using spring cloud to build micro service application, and now I need to create service monitoring solution to dynamically check status for each micro-service.
I am not seeing this supported in spring cloud, but I did see NetFlix is providing Srvo, does anyone ever used it or can anyone give some good suggestions on what will be best solution to monitor status for all the micro-services?
Thanks
Spring Cloud Netflix adds servo metrics to the standard spring boot /metrics actuator endpoint. See Spring Boot Production Ready Metrics to see about a MetricRepository. Here is some documentation on using redis. See this project for an example configuration.