If I have an AMI (EBS backed) from which I launch two instances, would both instances be entirely separate from each other? How does the underlying infrastructure work?
I find it a little overwhelming to get the entire idea to picture. Yes, I'm new to this whole AWS thing.
Yes, they're essentially like "twins" - both are made from the same genetic material (AMI) but each one is an individual person (server). Each instance must be completely decoupled from each other and able to survive on it's own without any knowledge or dependency on it's "twins" (other instances), otherwise you're heading into "conjoined twins" territory in the case of this metaphor!
Assuming each of these instances is for a web server, the thing that binds all of your instances together in the infrastructure is a "Load balancer". This is what will receive the requests to your application and pass it on to one of the web server instances - typically the one that is the least busy.
e.g.
Obviously there's much more to it than this, but this is the general idea.
Just an addition that if you have ip/DNS specific things in your AMI instance that yes, you would have to edit those after the new EC2 was created.
Related
When setting up EC2 with Amazon Web Services, is there any reason not to always use the cheapest instance (ie t2.nano - if you're going to be using tx.x based instances) and have it automatically scale up (note: UP, not OUT) to use what it requires?
Why start at a higher instance (eg. t2.micro, t2.small, t2.medium) if you don't necessarily need it?
Is the only reason not to, to ensure there's no performance issues while scaling auto-adjusts?
It seems automatically scaling UP is not available in AWS, and actually you have to scale OUT. With this in mind, it makes sense to always begin with the smallest instance that your app will run on well, which may not be the cheapest.
It's all based on your application usage. If your testing something in AWS with EC2 instance the T2 family instance is pretty fine and you can go ahead and use it. For Production, you can go with following instance base on your application.
Application usage:
CPU bouns use C4 Family
Memory bouns use R4 or m3 family
Storage bouns use d2,i2, and i3 family
Kindly find the following link for your reference.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html
Quite a broad question in my opinion as we know nothing about the underlying application so I'll give an example based on some assumptions on when it obviously wouldn't work.
I'm also assuming you're using auto scaling here and adding another instance type based on alarms and metrics?
For example if you had a single instance inside an autoscaling group for an important customer focused solution then for the duration that your system is potentially not serving requests quick enough because of the resource limit and while the scaling process is taking place then you're potentially losing custom and/or money. Especially if you've got to scale about 5 times to get to the right instance type.
Also, what's the bottleneck? If its network io then scaling through the T2 family won't help at all as you'd benefit from enhanced networking which is only supported on certain instances types. For general purpose you'd be wanting an m4 type.
Curious if this is possible:
We have a web application that at MOST times, works just fine with our single small instance. However, when we get multiple customers running simultaneously intense queries (we are a cloud scheduling service); our instance bogs way down to near 80% cpu load and becomes pretty unresponsive.
Is there a way to have AWS fire up another small instance (or a few), quickly, only for the times that its operating under this intense load? BUT, the real question is how does this work when we have very frequent programming updates to our application? Do we have to manually create a new image everytime we upload a code change???
Thanks
You should never be running anything important on a single EC2 instance. Instances can--and do--go offline randomly. Always use an autoscaling (AS) group that spans multiple availability zones. An AS group will automatically bring new instances online when you hit a certain trigger (in your case, CPU utilization). And then it will scale down the instances when traffic subsides. Autoscaling is the heart and soul of AWS and if you're not using it, you might as well be using a cheaper (and more durable) VPS host.
No, you don't want to be creating a new AMI for each code release. Ideally you should use a base AMI (like one of Amazon's official ones) and then have it auto-provision at boot. You can use the "user data" field when you launch an AMI to bootstrap this process. It can be as simple as a bash script that pulls from your Git repo to as something as sophisticated as Puppet or Chef.
The only time I create custom AMI's is if the provisioning process just takes too long. However that can almost always be solved by storing the needed files in S3.
I have had an EC2 instance working just fine for months (still developing, app not live yet), but I just realized I don't even know how to make my EC2 instance scale up / down depending on traffic.
The sheer number of services offered by Amazon is overwhelming, and I'm very confused.
Initially, I though I'd just have one instance, and Amazon would transparently allocate resources or create identical instances to handle traffic but it seems my impression was wrong.
My question is: can someone please tell me (in simple words, bullet list or point me to a tutorial) how to make my instance automatically grows to handle 100,000 simultaneous users then automatically goes back when the surge is done?
Assuming this is possible, can I do this via the AWS control panel? If so, how?
All I can see is micro, small, medium, etc.. instances. Each one has limited resources and it's not clear how to automatically setup the instance so that Amazon dynamically allocate additional resources to handle traffic spikes (or even gradually go up to keep with natural traffic growth for that matter).
Side question May I assume that Amazon auto-handle DDOS attacks when scaling up? (meaning rogue traffic would eventually stopped/slowed down by Amazon and scaling would only affect legitimate traffic spike). I realize this side question may be really stupid, keep in mind I didn't take my coffee yet :)
This article details how to auto scale using load balancers and EC2: http://kkpradeeban.blogspot.com/2011/01/auto-scaling-with-amazon-ec2.html
For scalability you may also want to look into this article on implementing a pub/sub system for distributed systems: http://www.infoq.com/articles/AmazonPubSub
You can't automatically change the instance type (m1.small, m1.large, etc.) in response to changing load. You can, however, have AWS automatically create new instances as your load increases, and tear them down when load subsides.
I believe this article will help you: http://aws.amazon.com/autoscaling/.
I do have a free micro instance on AWS and quite often my CPU is throttled making it very hard to use.
I do want to know if there is any way to test a bigger instance so I see which one would be ok.
Side questions:
Can I go back to the free micro if I want?
Can I limit the cost of the testing, or do an estimate on it? I don't want to endup with a surprise bill as the result of the testing.
You can of course launch a new instance of a larger size, run your tests, then terminate the instance. It will not effect your running micro instance in any way at all.
AWS publishes their pricing data, so you can either calculate the cost manually or use the cost calculator: http://calculator.s3.amazonaws.com/calc5.html
There is no way to "cap" your AWS spend.
Mike Ryan's answer is correct as such, but there might be a better way to achieve your goal, because it is possible to upgrade your Amazon EC2 t1.micro instance in place. This process (and the few constraints) are summarized in Eric Hammond's article Moving an EC2 Instance to a Larger (or Smaller) Instance Type:
When you discover that the entry level t1.micro instance size is
simply not cutting it for your growing application needs, you may want
to try upgrading it to a larger instance type, perhaps an m1.small or
even a c1.medium.
Instead of starting a new instance and having to configure it from
scratch, you may be able to simply resize the existing instance by
asking Amazon move it to better hardware for you. Of course, since
this is AWS, you don’t have to actually talk to anybody—just type a
few commands and the job is done automatically.
Eric describes how to achieve this via the command line, but the same can be done via the AWS Management Console as well if your prefer, the instance menu features a respective command Change Instance Type (only enabled when the instance is stopped).
Alternatively you might also want to get acquainted with the ease of duplicating an EBS-Backed EC2 instance by means of an Amazon Machine Image (AMI), which allows you to start any number of exact duplicates of your current instance - this process is outlined in Creating Amazon EBS-Backed AMIs Using the Console for example.
The company I work for built and hosts a web app used by our customers and I am interested in creating some kind of external monitoring page (similar to trust.salesforce.com) that users can go to to see the current state of our servers/app. I know there are tons of different 'monitoring' services out there but I want to create the service myself, to have complete control and customization. Obviously, the service would have to be hosted in a different location and data center than the app itself. One thing I am concerned about is that if I just choose a different host in a different location, if that host goes down for any reason (power failure, server failure, or even ISP failure) the monitoring software is down. For this reason, I am thinking of hosting the monitoring app on an amazon EC2 instance. With their elastic IP feature, if for some reason the data center or point where the instance is running fails, I can just create a duplicate instance with the same data (but in a different location) and everything would work fine still.
Does this sound like a feasible plan? For even more security, I was thinking of creating 2 instances in different locations and monitoring from both of them. If one instance fails, the other would still be up. Obviously, one instance has to act as the actual web host for the monitoring page. Is it possible programatically for one instance to switch the elastic IP over to itself if it detects the other instance has failed for any reason?
I know there's a lot of different things involved in this question, I'm just looking for feedback regarding ANY of it...
If you've made it this far, thanks for taking the time to read this!
What you are talking about is a complicated solution for a complicated issue. I think you are on the right track with using something like Amazon's EC2 to reduce the chance of your monitoring app of going down. Also, you could develop it yourself but there are a great deal of free monitoring solutions out there like Nagios that will do everything you are asking for and is highly extensible so you can spend your time making it look and feel like you want while leaving the more complicated portions under the hood to software that is tried and tested. The worst thing would be for you to have a bug in your software that shows something as up when it is actually down. Based off of what you are talking about doing, I would assume that would be a huge issue.
Instead of using an elastic ip - which is only assigned to one instance, consider using the Elastic Load Balancer http://aws.amazon.com/elasticloadbalancing/ which then can route over instances in any of the availability zones. This way AWS manages taking instances in/out of the pool if they become unavailable for some reason and you do not have to spend time 'moving' the Elastic IP around. It is then easy to assign your monitoring cname to the ELB hostname.
I think RandomBen's idea of using Nagios on your instances is a good one because then you do not have to recreate all the functionality in Nagios. You then spend development time setting up the system and customizing the look and feel to your needs.
Also, if you can use MySQL, you should consider using RDS http://aws.amazon.com/rds/ although you will need to pay transfer fees if you have servers outside of a region accessing the RDS in another region.