I tried to create a cluster in Apache Geode by providing the hostname and ip address of the remote system in the gemfire.properties file. Somehow, I am not able to create a cluster.
Can anybody please help with steps to create a cluster (including multi-site).
Thank you
It's not clear from the description if you just want to create a simple GemFire cluster or multiple clusters connected through the Geode WAN replication mechanism...
That said, to start a local Geode cluster you can go trough Apache Geode in 15 Minutes or Less, it's a quick introduction that shows you how to use gfsh to start a locator and some servers, create a region, monitor the system using PULSE, etc.
To setup WAN replication, on the other hand, you can go through Configuring a Multi-site (WAN) System, the most important thing to note about this configuration is that your locators need to know about the locators on the remote system, so you need to make sure that the property remote-locators is correctly configured. Once the locators can talk to each other over the WAN, they will share the connection information with the local servers and these, in turn, will be able to communicate with the servers on the remote clusters.
Hope this helps.
Cheers.
Related
We are using prometheus in our production envirment recently. Before we only have 30-40 nodes for each service and those servers not change very often, so we just write it in the prometheus.yml, but right now it become too long to hold in one file and change much frequently then before, so my question is should i use file_sd_config to put those server list out of yml file and change those config files sepearately, or using consul for service discovery(same much easy to handle changes).
I have install 3 nodes consul cluster in data center and as i can see if i change to use consul to slove this problem , i also need to install consul client in each server(node) and define its services info. Is that correct? or does anyone have good advise.
Thanks
I totally advocate the use of a service discovery system. It may be a bit hard to deploy at first but surely it will worth it in the future.
That said, Prometheus comes with a lot of service discovery integrations. It's possible that you don't need a Consul cluster. If your servers are in a cloud provider like AWS, GCP, Azure, Openstack, etc, prometheus are able to autodiscover the instances.
If you keep running with Consul, the answer is yes, the agent must be running in every node. You can also register services and nodes via API but it's easier to deploy the agent.
I am trying to setup a distributed system based on current spring-cloud release (meaning mostly Netflix OSS) using the following components
1 or more cloud config servers
1 or more Eureka servers
1 or more services using Eureka and Config Server clients
The setup above is easy enough to get going however once you start looking into setting up so that configuration changes in the cloud Config servers automatically trigger changes in the values of the actual clients, things start getting more complicated.
It is my understanding that for such a feature to work one should introduce spring-cloud-bus clients to the services which in turn will use, currently the only supported implementation, rabbitmq servers (the actual rabbitmq binaries and not some spring-boot app like eureka or Config servers) to allow change events in the Config server to be propagated to the clients automatically.
It sounds counterintuitive to setup such a system and have to hardcode addresses to rabbitmq servers in the clients (even if one will be keeping the amount of rabbitmq servers more or less static).
How is one supposed to register rabbitmq server instances in the Eureka service discovery server(s) to allow for clients to find them without having to have any knowledge about their location prior to startup?
I cannot seem to find any documentation on how this is done given that rabbitmq is not a spring-cloud component. In fact very little documentation seems to exist regarding on how the rabbitmq + eureka + spring-cloud-bus should be setup together.
I know that I am on a VERY old question, even though I think it worth a comment for people who read this in the future.
Most of the cloud services, lets take AWS as an example, have an Elastic IP solution - so you can configure IPs for RabbitMQ servers, and the IPs always belong to the RabbitMQ, no matter whether the instances change. You can re-attach the Elastic IP to different instances.
It works nearly the same with Elastic Load Balancer, which keeps its IP, so you could configure your microservices to a specific IP using Spring Cloud Config Server - and scale the RabbitMQ instances without a need to worry about configuration change.
Currently I have the following setup:
Hardware load balancer directing traffic to two physical servers each with 2 instances of weblogic running.
Works ok. I'd like to be able to shutdown one of the servers without dropping active sessions. Right now if I shutdown one of the physical servers any traffic that was going there gets bounced back to a login screen.
I'm looking for the simplest way of accomplishing this with the smallest performance hit.
Things I've considered so far:
1. See if I can somehow store the session information on the Load Balancer and through some Load Balancer magic have it notice a server is dead and try another one with the same session information (not sure this is possible)
2. Configure weblogic clustering. Not sure what the performance hit would be. Im guessing this is what I'll end up with, but still fishing for alternatives.
3. ?
What I currently have is an overly designed DR solution (which was the requirement), but I'd like to move it more in the direction of HA (for the flexibility)
edit Also is it worthwhile to create 2 clusters and replicate the sessions between them (I was thinking one cluster per site, sites are close enough). This would cover the event of one cluster failing.
You could try setting up a JDBC Session Storage pointing (of course) both instances to the same datasource without setting up a cluster, but I think the right approach would be setting up a Weblogic Cluster.
A nice thing about clustering Weblogic Servers is that - (from the link above, emphasis mine):
Sessions can be shared across clustered WebLogic Servers. Note that session persistence is no longer a requirement in a WebLogic Cluster. Instead, you can use in-memory replication of state. For more information, see Using WebLogic Server Clusters.
We've got a write up of this on our blog http://blog.c2b2.co.uk/2012/10/basic-clustering-with-weblogic-12c-and.html which provides step by step instructions on setting up web session failover in a cluster.
Clusters are not heavyweight assuming you don't store huge amounts of data in the cluster as it will be replicated.
Can someone explain to me how high-availability ("HA") works for a web application ... because I assume HA means that there exist no single-point-of-failure.
However, even if a load balancer is used- isn't that the single point of failure?
I have found this article on the subject:
http://www.tenereillo.com/GSLBPageOfShame.htm
Basically if you do not require long lasting sticky sessions you can configure your DNS servers to return multiple A records (IP addresses) for your website.
Web browsers are smart enough to try all the addresses until they find one that works.
In simple words high availability can be defined as running a system 24*7 without a downtime even if there are hardware and software failures. In other way a fault tolerance application. This helps ensure uninterrupted use of the application for it’s intended users.
Read more on High Availability Deployment Architecture
It works the following way that you setup two HA Proxy servers with heartbeat, so when one fails (stops responding to queries), it's being removed from the cluster.
Requests from HA Proxy can be forwarded to web servers in round robin fashion, and if one web server fails, HA Proxy servers do not try to contact it until it's alive.
Web servers are storing all dynamic information in database, which is replicated across two MySQL instances.
As you can see, HA Proxy and Cluster MySQL (or simply MySQL replication) as well IP Clustering here is the key.
Sure it is when operated alone. Usual highly available setup includes 2 or more load balancers running in cluster in either active/active or active/passive configuration. To further increase the availability you can have 2 different Internet Service Providers (or geo distributed datacenters) each running a pair of clustered load balancers. Then you configure DNS A record resolving to 2 distinct public IP addresses which guarantees round-robin processing splitting DNS requests evenly (CloudFlare is very fast and reliable at this). There's also possibility to return IP address of datacenter closest to your originating geo location by using something like PowerDNS dnsdist
This is what big players do to make their services highly available.
Please read https://docs.oracle.com/cd/E23824_01/html/821-1453/gkkky.html for more clearity. Actually both load balancer uses same vip(Virtual IP Address. https://techterms.com/definition/vip).
HA architecture is a entire field and multiple books were written on it, so it is hard to answer in a short paragraph.
To sum up the ideal situation, you would be using multiple servers, interconnected to a layer of multiple load balancers. The nodes and LB will be located in a few different data centers, and connected to different network backbone. Ideally the data centers will be located all over the world.
In short, all component will have redundancy, including the load balancers.
For a starting point, see Wikipedia for High Availability Cluster
I have a Glassfish v2u2 cluster with two instances and I want to to fail-over between them. Every document that I read on this subject says that I should use a load balancer in front of Glassfish, like Apache httpd. In this scenario failover works, but I again have a single point of failure.
Is Glassfish able to do that fail-over without a load balancer in front?
The we solved this is that we have two IP addresses which both respond to the URL. The DNS provider (DNS Made Easy) will round robin between the two. Setting the timeout low will ensure that if one server fails the other will answer. When one server stops responding, DNS Made Easy will only send the other host as the server to respond to this URL. You will have to trust the DNS provider, but you can buy service with extremely high availability of the DNS lookup
As for high availability, you can have cluster setup which allows for session replication so that the user won't loose more than potentially one request which fails.
Hmm.. JBoss can do failover without a load balancer according to the docs (http://docs.jboss.org/jbossas/jboss4guide/r4/html/cluster.chapt.html) Chapter 16.1.2.1. Client-side interceptor.
As far as I know glassfish the cluster provides in-memory session replication between nodes. If I use Suns Glassfish Enterprise Application Server I can use HADB which promisses 99.999% of availability.
No, you can't do it at the application level.
Your options are:
Round-robin DNS - expose both your servers to the internet and let the client do the load-balancing - this is quite attractive as it will definitely enable fail-over.
Use a different layer 3 load balancing system - such as "Windows network load balancing" , "Linux Network Load balancing" or the one I wrote called "Fluffy Linux cluster"
Use a separate load-balancer that has a failover hot spare
In any of these cases you still need to ensure that your database and session data etc, are available and in sync between the members of your cluster, which in practice is much harder.