I'm using the Amazon MQ managed service and have a question as to how MQ behaves on a reboot.
Will the private IP of the broker change or is it static?
I'm using Amazon MQ inside of a VPC.
Assuming you're using a single instance broker it will most likely stay the same. I couldn't find a direct documentation reference for this, but Amazon MQ broker nodes are managed EC2 instances. An EC2 instance by default retains the private IP inside a VPC over its lifecycle.
The problem is that you don't control the lifecycle of the instance. If the instance is broken beyond repair, Amazon MQ may set up a new instance for you, which will get a different private IP address inside the VPC, but that should be rare. After a simple reboot that would be very unlikely.
If you're using an active/standby cluster what I said concerning the IPs of the individual nodes should still be true, but the whoever the active node is may change.
If you need a hard guarantee that the IP addresses don't change, you can set up a private Network Load Balancer in front of your cluster. From the docs (emphasis mine):
When you create an internal load balancer, you can optionally specify one private IP address per subnet. If you do not specify an IP address from the subnet, Elastic Load Balancing chooses one for you. These private IP addresses provide your load balancer with static IP addresses that will not change during the life of the load balancer. You cannot change these private IP addresses after you create the load balancer.
For most services in AWS you want to use the DNS name or CNAME to a service instead of any IP address unless there's a static IP address attached to it.
Related
I have a scenario where I want to setup an haproxy cluster with keepalived. I saw this blog post https://www.peternijssen.nl/high-availability-haproxy-keepalived-aws/ and its pretty detailed and easy to follow, but for my scenario I need the elastic IP's to be private. Is this doable ? As from AWS documentation Elastic IP's are only public IPs.
I need a floating IP which will act as a floating cluster IP. What can I use if Elastic IP is not an option.
An elastic IP within AWS is actually a static public IP address. This functionality is required as by default a public IP address is not reserved by an account, and when enabled limits the total IPv4 addresses you can keep.
For private address ranges however, your instances can be assigned any private IP address that is within any of your VPCs CIDR range(s).
In fact for this reason you can select almost any IP address found within your VPC when launching a new instance, in addition the IP addresses that are attached to an EC2 instance are static and will be attached to that instance until it is terminated.
Therefore as long as you don't terminate the instances the private IP(s) will be maintained. However, in the event the instance fails and is not recoverable you would still need to launch a new instance and use that IP.
It might be more beneficial using a DNS record to resolve the IP just in case of an emergency, or failing that use a load balancer to distribute traffic.
For this case you can provision an Elastic Network Interface (ENI) with a static private IP address which you can attach/re-attach to EC2 instances. As long as you don’t delete the ENI, it will retain the I as p address. Find out more here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-eni.html
I created an elastic IP for my EC2 Instance and Route53 routes instance to my domain using that elastic IP.
However, someone mentioned the idea of connecting the Elastic IP to a network interface and then connecting the network interface to the EC2 Instance...
What's the point in adding the network interface in between and should I do it?
Elastic IP is always attached to a network interface.
However, when you attach address directly to an instance, AWS attaches it to instance's primary network interface, replacing any existing IP this interface had already attached to it. So the use case for attaching IP to an interface first, for example, includes the need to preserve the IP which is already associated with instance's primary NI.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/elastic-ip-addresses-eip.html#eip-basics
If you created multiple network interfaces, you could select to associate the EIP to a particular NI. You may have created multiple NI for load balancing, private communication a backup network between instances. You could configure connection to database servers as such.
After restarting AWS EC2, hostname & public IP gets changed.
Remote docker clients get affected as they rely(export DOCKER_HOST) on these public names.
How to resolve this dynamic IP(public) problem of EC2?
By default, AWS assigned public IP addresses as well as hostnames are ephemeral, meaning they will be released back to the pool if you restart the instance. If you really need a persistent IP address, you can use Elastic IPs, but bear in mind there’s a limit per region.
Note: I’d still recommend evaluating the need for using a public IP from the IPv4 pool, as they are a rare resource. Most of the times, one can get by well by using the correct combination of security groups and private IPs, along with Route53 hosted zones for friendly naming, assuming instances are in the same VPC or can communicate via VPC peering.
I am new to AWS and tried to create an EC2 instance.
I have a domain and ready to modify the A record to the associated EC2 instance.
I found an article that said an elastic IP is required for associating a production domain.
But AWS provides a public IP and it is accessible on the public internet too (i know it changes after restart, just assuming its okay to modify the A record after the machine is restarted - actually it is not restart very often).
In this case, is it a must that to assign an elastic IP to the instance (this instance contains no load balancing, it is only a simple single instance)?
If yes, why is it necessary?
An Elastic IP (EIP) is not necessary provided that you understand the limitations of public IPs. You may not reboot your instance, but AWS might for any number of reasons. This means that the public IP address could change when you are not expecting it.
When an EIP is assigned to a running EC2 instance, there are no charges for the EIP e.g. it is free. Therefore why go thru the hassle of needing to monitor your public IP address.
I am trying to setup couchbase cluster on AWS. I want my nodes to be distributed across multiple availability zones.
Ec2 instances with in an availability zone are able to access each other using the ip (Private DNS) which is assigned to them during creation and which does not change even if we restart the machine.
I am not able to access an Ec2 instance from other AZ using this (Private DNS). One way this can be done is by using Elastic Ip which has a limit per region.
Question here is How to access one Ec2 instance from other EC2 instance in another AZ without elastic ip?
You do not want to use Elastic IP for this. Your statement that Elastic IP is a solution to your issue is not correct. You want to use the Private IP assigned to the instance when you created it.
The private IP will not change as long as the instances are deployed inside a VPC.
You have to use the private IP in order to keep all network traffic inside the VPC. Then you just need to make sure your Security Groups are configured correctly to allow traffic between the instances.
Amazon Web Services Operates Split-horizon DNS (AKA Split-Brain DNS). The best practice when deploying couchbase onto EC2 is to use hostnames not IP addresses, see http://developer.couchbase.com/documentation/server/current/install/cloud-deployment.html . Amazon will automatically give a different IP when resolving the hostname depending if the source of the request is internal or external.