Looking for advice on the recommended way of setting up autoscaling for a pair of EC2 instances running a Nginx-based web service behind an ELB.
I understand that I'll need to use CloudWatch to monitor my EC2 instances - is it sufficient to save my EC2 instance as an AMI image and then have CloudWatch fire up new instances using that image (with ELB automatically routing requests in round-robin fashion to available instances)?
You can attach your load balancer to your Auto Scaling Group (ASG). When attached, the load balancer automatically registers the newly launched instances in the group and distributes the traffic across them. For adding health checks to the ASG with a load balancer attached to it, you need to:
Go to EC2 console
Choose Auto Scaling Group under Auto Scaling
Select your group and click Actions and then Edit
Select ELB for Health Check Type and set the period (e.g. 300)
Save
Note that an ASG with EC2 health check type will not automatically replace the unhealthy instances. Read more here.
Related
I am trying to load some rest services using cloudformation as ECS Service with Fargate.
I don't want a public domain name for these services. I will access them internally from my AWS Lambda functions.
I realized AWS Fargate needs load balancing and Load balancer needs certificate and certificates needs a domain name.
Probably I am missing something but I tried to load AWS Fargate without a load balancer and I was unable to access it from Lambdas.
The question is; how do I run my services on ECS with Fargate without Load Balancer?
Use ECS Service Discovery to set up private DNS records that allow your application to discover service endpoints without using a load balancer or having to create public DNS records. Service Discovery works by creating private DNS records in Route 53 that are queryable from within your VPC, so that you can find the IP addresses for all of the tasks running in a service. If you're running multiple tasks you will get multiple A records back, one per task, so you will need to do client-side load balancing by picking a random record in the returned set.
The documentation linked above is a little vague so here are some more specific instructions: When creating your service in the console, in Step 2: Configure Network, check the Enable service discovery integration checkbox. Then specify "create new private namespace" and supply a name for your namespace, such as foo.app. Then select the "Create new discover service" radio button, and specify a name for your service (such as service1). Leave the rest of the settings in the Service discovery (optional) section as default.
Now from within your VPC, you'll be able to look up service1.foo.app and get back A records with the IP addresses of all of the tasks running in the service.
This medium article also has a good summary of how to set up service discovery.
I have a database server on a EC2 instance, I want it to accessible by Elastic Load Balancer cluster.
I tried adding the subnet of the Load Balancer security groups of database EC2.
There must be some way to give whole cluster of EC2 instance created ELB and autoscalling, access to single EC2.
Your question isn't too clear, but it appears your scenario is:
Internet -> ELB -> EC2 fleet -> Database (on EC2 instance)
You have a database running on a single EC2 instance
You have multiple EC2 instances running an application that connect to the database
You have an Elastic Load Balancer that accepts traffic from the Internet and distributes it to the EC2 instances running the application
You should configure the following Security Groups:
ELB-SG: Configure this security group to allow incoming web traffic from the Internet (0.0.0.0/0). Associate the security group to the Load Balancer.
App-SG: Configure this security group to allow incoming web traffic from ELB-SG. Associate the security group with every instance in the application fleet. If the EC2 instances are launched via Auto Scaling, then associate the security group with the Launch Configuration.
DB-SG: Configure this security group to allow incoming traffic from App-SG. Associate the security group to the EC2 instance running the database.
When I say "allow incoming traffic from xxx-SG", I mean that you should enter the name of the incoming security group in the Source field when configuring the security group. This will automatically insert the unique name of the security group (sg-xxxx). It means that any resource associated with the referenced security group will be allowed incoming access on the nominated port.
You should avoid using an IP address or CIDR range in a security group, because they can change (eg if you launch another EC2 instance). By referencing a security group by name, it will automatically update as instances are added/removed.
There is single EC2 instance deployed behind a ELB using Cloud Formation and now I am trying to add cron jobs to crontab by updating CF stack, however after updating the stack I rebooted the server but the changes are not reflecting on the server.
It seems like the application on the server is only rebooted not the OS of the server. When I checked status of ELB after reboot, instance state is out of service and instance state on the EC2 tab is showing running.
Note: There is no autoscaling group attached.
Check if your application on EC2 instance is listening on the port mentioned in loadbalancer.
Is there a way to attach instances in an autoscaling group directly to a Application Load Balancer (ALB) target. My ASG works but they are not attached to the ALB Targets when they are initiated.
The aws_autoscaling_group resource has a target_group_arns option:
https://www.terraform.io/docs/providers/aws/r/autoscaling_group.html
Is there any way to make new instances added to an autoscaling group associate with an elastic IP? I have a use case where the instances in my autoscale group need to be whitelisted on remote servers, so they need to have predictable IPs.
I realize there are ways to do this programmatically using the API, but I'm wondering if there's any other way. It seems like CloudFormation may be able to do this.
You can associate an Elastic IP to ASG instances using manual or scripted API calls just as you would any other instance -- however, there is no automated way to do this. ASG instances are designed to be ephemeral/disposable, and Elastic IP association goes against this philosophy.
To solve your problem re: whitelisting, you have a few options:
If the system that requires predictable source IPs is on EC2 and under your control, you can disable IP restrictions and use EC2 security groups to secure traffic instead
If the system is not under your control, you can set up a proxy server with an Elastic IP and have your ASG instances use the proxy for outbound traffic
You can use http://aws.amazon.com/vpc/ to gain complete control over instance addressing, including network egress IPs -- though this can be time consuming
There are 3 approaches I could find to doing this. Cloud Formation will just automate it but you need to understand what's going on first.
1.-As #gabrtv mentioned use VPC, this lends itself to two options.
1.1-Within a VPC use a NAT Gateway to route all traffic in and out of the Gateway. The Gateway will have an Elastic IP and internet traffic then whitelist the NAT Gateway on your server side. Look for NAT gateway on AWS documentation.
1.2-Create a Virtual Private Gateway/VPN connection to your backend servers in your datacenter and route traffic through that.
1.2.a-Create your instances within a DEDICATED private subnet.
1.2.b-Whitelist the entire subnet on your side, any request from that subnet will be allowed in.
1.2.c Make sure your routes in the Subnet are correct.
(I'm skipping 2 on purpose since that is 1.2)
3.-The LAZY way:
Utilize AWS Opsworks to do two things:
1st: Allocate a RESOURCE Pool of Elastic IPs.
2nd: Start LOAD instances on demand and AUTO assign them one elastic ip from the Pool.
For the second part you will need to have the 24/7 instances be your minimum and the Load instances be your MAX. AWS Opsworks now allows Cloud Watch alarms to trigger instance startup so it is very similar to ASG.
The only disadvantage of Opsworks is that instances aren't terminated but stopped instead when the load goes down and that you must "create" instances beforehand. Also you depend on Chef solo to initiate your instances but is the only way to get auto assigning EIPs to your newly created instances that I could find.
Cheers!