In the last but one post of this series we'll try to run a simple cluster of 3 nodes running EventStore instances. What is worth noting here is the fact, that there're three ways to organize and configure instances, so they work with each other:
- running them on the same machine
- running them on separate machines using IPs
- running them on separate machines using DNS
Because the first one is almost self-describing(you have to start three instances on different ports), we'll omit it here and focus on the more complicated examples.
Running on separate machines
We'll start with creating 2 additional machines for our purposes. Just create two additional VM instances in the resource group you're using just like in the very first post of this series and we're good to go. Make sure that you're creating them in the same virtual network, which was created for the first virtual machine.
Once VMs are created, log in to each one and install EventStore instances as described in the previous posts.
Now we have to configure our instances so they're aware of other nodes. Basically what you have to do here is to change configuration on each node so it knows cluster size and other communication partners. Your eventstore.conf file could look like this:
The important thing here is the GossipSeed property, which points to other cluster nodes. I'm using here private IPs so my instances are still secured inside the network. The important thing here is that ES uses internal HTTP port for gossiping so make sure you're using the right value - if anything's wrong, election service won't be able to other machines and you'll see DEAD as other nodes status.
Configure all three nodes with proper gossip seeds and IPs by modifying each one's configuration file. Once you're done, go to the web panel of ES and sign in as admin.
Checking cluster status
If you sign in to the web panel, you'll see Cluster status menu item:
It will show all nodes attached, current state(which one is a master) and many, many more. I strongly recommend you to play a bit with it.
We've managed to create a cluster of 3 different machines running EventStore using VMs from Azure. In the last part of this series we'll try to use DNS instead to ease configuration a bit if anything changes.