How many concurrent users can be connected to (i.e. SSH into) an EC2 instance? Is there a limit?
AWS EC2 instances are just virtual machines running your favorite flavor of operating system. There are no AWS restrictions as to how many users you can create inside of it, or how many can connect at one time other than whatever limit the operating system may have.
Note: there are instance size limits (memory/cpu) that might affect your users' ability to connect.
Related
So I want to launch a web application, and run it on containers in AWS.
I want to give users access to the tool through a log in page.
I don't understand how AWS manages the relationship of containers and the instances backing them.
My main questions are -
Will multiple containers run on a single ec2 instance?
If the compute power required by a container exceeds the processing power of a single instance, and I have auto-scaling enabled, will it launch multiple instances to support a single container? or will I need to go in and upgrade my ec2 instance type?
Finally, when users log in to the app, will AWS deploy a new container for each user, and subsequently a new instance to run on? or can one container support multiple users?
Also a link to a page where I can find this information would be tremendously helpful.
I will try to answer your questions, but how #Ermiya Eskandary said, the documentation will answer all the questions about container in AWS.
Yes, if your have for example a 2gb memory and 1vcpu ec2 instance and your container need a 500mb memory and 0,25vcpu, you can run a lot of containers inside EC2. You can set the task placement group to tell AWS how to handle container into EC2: https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-placement.html
No, if your container size exceeds your ec2 instance, is impossible to share the resources of multiple ec2 to hold on one single container. If you are using ecs core (ec2 mode), the ec2 size always need to be bigger than the container.
No, you will use one container to attend multiple clients, if you are running out resources, your ASG will increase number of tasks running, using the rule that i said in the first point.
To finish, based on my experience, if your use case don't need to work with cores of machine, using a custom AMI or any other thing in the infrastructure level (linux/windows), i would use ec2 fargate.
Fargate have less operational overhead, since you need to orchestrate auto scalling group both in ec2 and in your tasks using ecs with ec2.
Sometimes I have noted that If I don't apply updated security packages in some EC2 instances on AWS then instances run slower. I have seen it repeatedly on different machines. Is it possible that Amazon is applying some policies for machines that are not updated?
AWS has zero insight into what you run on an Amazon EC2 instance. You are responsible for installing and maintaining the operating system, applications and data. AWS is responsible for providing the platform that enables the virtual machine.
Every Amazon EC2 instance is given resources (CPU, RAM, Network) based on the Instance Type. The same instance type will always receive the same amount of resources, and the resources are not over-subscribed.
Therefore, any slowdown that you might observe would be related to the operating system and software that you are running on the instance. You can use standard monitoring tools to inspect the operating system to investigate what might be happening.
I am trying to wrap my head around EC2 instances, and I am having a bit of an issue. I heard from a friend of mine that Amazon will kill EC2 instances, and then they restart the image (thus losing all state). Unless it uses EBS as a backing store, you get no persistence.
But I have been looking into Xen and it seems like instances should easily migrate instead of being killed/restarted.
So, do Amazon EC2 instances randomly stop/start an image with all state being managed by something external like EBS?
Amazon EC2 instances will not be stopped/started/restarted unless you issue a command to do so.
In some situations (eg hardware maintenance), you might receive a request from Amazon asking you to stop & start your instance (which moves it to a different host). Such requests are typically issued with two weeks notice.
One AWS customer told me that their instance had been running continuously for over three years.
Yes it is quite possible that an EC2 instance dies and is replaced. Depending upon your data, you may need to use EBS, EFS or S3 to prevent data loss in such cases.
I plan to setup autoscaling on my api nodes, but want them to connect to the same RDS instance (with Multi AZ).
Will i notice any performance impacts if the api nodes all share the same db account?
Otherwise, what alternatives do i have that wont complicate the deployment process significantly?
Thanks
A database user account is used to control security (eg Is the user allowed to perform a command) and logging (eg Which user deleted the table?).
Having applications on multiple Amazon EC2 instances use the same database user account will not impact performance. Two requests coming from different database users will use the same amount of resource as two requests coming from the same database user.
An exception to this would be if any database configurations restrict resources by user, such as processing queues. However, this would not be a default behavior.
I am about to launch an iOS app that will be communicating with my custom REST API. Right now I am running a single EC2 t2.micro instance running an Apache web server with MySQLi. Before I go ahead and launch it for the public, I want to hear what proper steps should be taken regarding the following.
Should I run two separate EC2 instances? One only for the web server and the other to handle only the database?
How should I approach setting up the database? Should I still use MySQLi or should I start using Amazon's RDS?
In relationship to number two, when the database and/or web server runs out of space, how is this issue handled so that it seamlessly adds space to allow the database/web server to continue growth? I also read something regarding auto-scale.
I will be expecting many requests per minute to my web server and want to take precaution.
The answer to these questions largely depends on the requirements of your application, your budget, and on what you decide to manage vs. what you'd prefer to allow AWS to manage. However, I'll answer these as best I can.
1) Yes. Separating the database from the web server (that is, 2 different EC2 instances) makes sense for a lot of reasons. This will allow you to tailor resources like memory, CPU, etc. to each layer of your application separately. You do not want your web and database competing for the same resources. Additionally, an issue that forces you to take down one (web or database) will not force you to also take down the other. If your database lives on one of the web servers and you need to perform maintenance, your app will effectively become offline, since down goes your database as you perform updates. Also, ideally you would protect your database server within a private subnet in your VPC. If you have the web and database on the same server, they will both be in a public subnet, since you're web will require access to an internet gateway.
2) Depends. If you want to maintain total control of the database server, than use an EC2 instance where you retain operating system control. If you want to take advantage of features like Multi-AZ for high availability or allowing AWS to manage things like updates for you, RDS can be a great option. Cost also plays a role. For things like read-replicas and Multi-AZ, you will pay more, but you are purchasing performance and high availability. Thus, depends on your requirements. You can find the features of RDS here: RDS Product Details
3) For anything running on an EC2 instance (database or web) or if you decide to use RDS, you may provision and attach additional storage volumes as necessary. The type of storage you select will depend on the performance requirements, your budget, and the kind of workload you expect your database to face. Amazon provides the storage options available to you as well as a section for adding more storage here: RDS Storage Options
If you are worried about too many requests overwhelming your EC2 t2.micro instance, consider creating an ELB load balancer and setting up an auto-scaling group which will allow you to expand your capacity as necessary while distributing traffic such that no one server gets overwhelmed.