Is it “okay” to host a small wordpress blog on one

问题:

This is a very simple question for those with the knowledge, but I'm a newbie.

In essence, I just need to know if it would be considered okay to run a small, approx. 700 visitors/day bitnami wordpress blog on just one t2.medium EC2 instance (without any auto-scaling, beanstalk).

Am at risk of it crashing? What stats should I monitor or be aware of to be aware of potential dangers? Sorry for the basic nature of these questions, but this is new.

回答1:

tl;dr: It might be "okay", but it's not ideal.

If your question is because of:

• Initial setup time - Load-balancing and auto-scaling will be less expensive (more time-efficient) over time.
• Cost - Auto-scaling spins down instances that aren't being used to reduce cost.
• Minimal setup for a great user experience - The goal of a great AWS setup is to ensure that capacity matches demand

Am at risk of it crashing?

Possibly, yes. If you average 700 visitors, then the risk is traffic spikes if all visitors hit at the same. It also depends on what your maximum visitors are, which could vary widely from the average (or not)

What stats should I monitor or be aware of to be aware of potential dangers?

• Monitor the usage on high traffic days (ie. public holiday sales)
• Setup billing alerts
• Setup the right metrics:

See John Rotenstein's SO answer:

CPU Utilization is not always the right measure to use -- your application might only be able to handle a limited number of connections, it might be squeezed on RAM and the types of requests might vary too.

You can use normal monitoring tools, or you can write something that pushes metrics to Amazon CloudWatch, so that you go beyond the basic CPU and Network metrics that CloudWatch normally provides. You could even use the Load Balancer's Latency metric to trigger scaling when the application slows down (custom code required).

I'd start with:

• Two or more instances - to deal with instance redundancy (an instance going down)
• Several t2.small rather than one t2.medium can work out to be more cost-efficient, and more cost efficient than EC in some use cases.
• Add auto-scaling - automatically spin up or down instances based on minimum and maximum counts
• Load balancing - to re-route users from unhealthy to healthy instances. And also to keep all of the spun up instances all working as evenly as possible (rather than a single instance handling 80% of the workload while the others bludge).

You can always reduce your instances after time with monitoring.

回答2:

In my opinion, with 700 visitors a day, the safer option would be to run a load balanced/auto-scaling environment on Elastic Beanstalk with at least 2 instances. The problem with running just one instance is that yes you are at a great risk of crashing in case you get an increase in traffic or when the instance goes down and with just one running you will not have a fallback. You can easily set up CloudWatch monitoring on NetworkIn, NetworkOut to get a sense of the number of requests your site is receiving and serving, and setup CPU Usage monitoring as well. The trade-off with running a load balanced environment over a single instance environment is that the cost might significantly increase as you introduce other things into your environment such as a load balancer. Also if you introduce a load balancer consider reducing the instance size to maybe a t2.small, could aid in reducing the cost.

回答3:

It actually depends. This question range is wide. You have multiple options here.

1. You can use only ec2 instance for that much amount of visitors or even more if your application allows. You can also consider caching if your app need it.

2. You may add instance in an autoscaling group. So that if by any chance you need more resources you can increase them horizontally.

3. You can add load balancers lateron also. You just need to add user data in your launch configuration attached to autoscaling group. So when your instance get up it should automatically register itself in your load balancer.

For monitoring, you can check for the request metrics in cloudwarch for ELB. You have to keep an eye on your CPU and trigger the scale out policy once it reaches a particular threshold.