For my fairly modest web application, I seem to be hitting some of the AWS VPC limits, which made wonder if I'm maybe structuring things incorrectly:
I have an application for which we have three environments: Staging, QA, Production. So I have a VPC for each.
These three VPCs exist in the US-East-1 Region
Each Application is available in two availability zones (us-east-1b & us-east-1c)
An example of a limit I'm hitting is for the following circumstance:
I have Public and Private facing subnets. And because I'm using two Availability Zones, I have Public and Private Subnets for each (4 subnets in total, per VPC)
The Private Subnets need internet access, so their respective Route Tables have entries for NAT Gateways.
So in the end, this means each Private Subnet has a NAT Gateway, and therefore each NAT Gateway has an Elastic IP. And because I have three environments, and two Availability Zones for each, that's already 6 Elastic IP addresses, and the Elastic IP limit per Region is 5.
So obviously, I can request an increase, but it made me wonder if I'm doing something wrong. Could some of these resources in fact share NAT Gateways, or Elastic IPs, or something to that effect?
You're not doing anything wrong, but you could be doing some things better.
Since you have 3 separated environments, you could separate the environments into separated AWS accounts.
For example, it's not uncommon to have Development in one AWS account, and Staging + Production in another AWS account. This has the added benefit of separating resources, identities, etc. for security purposes and avoids "oh $#&!, I just deleted the production stack by mistake".
Related
I'm new to AWS. I have deployed an interface endpoint in two subnets of my VPC. The endpoint comes with three domain names.
vpce-xxxxxxxxxxxxxxx-yjkfe3jc.vpce-svc-xxxxxxxxxxxxxxx.eu-central-1.vpce.amazonaws.com (Z273ZU8SZ5RJPC)
vpce-xxxxxxxxxxxxxxx-yjkfe3jc-eu-central-1a.vpce-svc-xxxxxxxxxxxxxxxx.eu-central-1.vpce.amazonaws.com (Z273ZU8SZ5RJPC)
vpce-xxxxxxxxxxxxxxx-yjkfe3jc-eu-central-1b.vpce-svc-xxxxxxxxxxxxxx.eu-central-1.vpce.amazonaws.com (Z273ZU8SZ5RJPC)
Two of them, which have the availability zone name inside their name, apparently points to the IP addresses of the ENIs in the subnets. However, I'm wondering what's the purpose of the first record(the one without AZ name)? And where are these records hosted or where to find the zone Z273ZU8SZ5RJPC?
Thanks!
First One is the regional DNS name of the endpoint, which will resolve to all the available zonal IP addresses associated with the endpoint.
[] Interface VPC endpoints (AWS PrivateLink) - Access a service through an interface endpoint - https://docs.aws.amazon.com/vpc/latest/privatelink/vpce-interface.html#access-service-though-endpoint
If you have created a HA architecture, with multiple resources spanning across multiple AZs, then the regional endpoint can be used. A simpler example can be for load balancing, where you are distributing load across multiple AZs using Round-Robin DNS resolution.
Since the hosted zone is not visible in our own account, it must be something AWS managed and therefore, we cannot see the records present in it.
Why I should configure an AWS ECS Service or an EC2 Instance with two or more Private Subnets from the same VPC? What would be the benefits of doing such thing instead of configuring it within just one Subnet? Would it be because of availability? I've read the documentation but it was not clear about it.
Reference: https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Subnets.html
This is generally to distribute your ECS service across multiple availability zones, allowing your service to maintain high availability.
A subnet is bound to a single AZ, so it is assumed each subnet is in a different AZ.
By splitting across multiple subnets, during an outage load can be shifted to launch containers entirely in other subnets (assuming they're in different AZs).
This is generally encouraged for all services that support multiple availability zones.
More information on Amazon ECS Availability best practices are available from the blog.
I have been reading and watching everything [1] I can related to designing highly available VPCs. I have a couple of questions. For a typical 3-tier application (web, app, db) that needs HA within a single region it looks like you need to do the following:
Create one public subnet in each AZ.
Create one web, app, and db private subnet in each AZ.
Ensure your web, app and db EC2 instances are split evenly between AZs (for this post assume the DBs are running hot/hot and the apps are stateless).
Use an ALB / autoscaling to distribute load across the web tier. From what I read ALBs provide HA across AZs within the same region.
Utilize Internet gateways to provide a target route for Internet traffic.
Use NAT gateways to SRC NAT the private subnet VMs so they can get out to
the Internet.
With this approach do you need to deploy one Internet and NAT gateway to each AZ? If you only deploy one what happens when you have an AZ outage. Are these services AZ aware (can't find a good answer for this question). Any and all feedback (glad to RTFM) is welcomed!
Thank you,
- Mick
[1] Last two resources I reviewed
Deploying production grade VPCs
High Availability Application Architectures in Amazon VPC
You need NAT Gateway in each AZ as the redundancy is limited to a single AZ. Here is the snippet from the official documentation
Each NAT gateway is created in a specific Availability Zone and
implemented with redundancy in that zone.
You need just a single Internet gateway for a VPC as it is redundant across AZs and a VPC level resource. Here is the snippet from Internet Gateway offical documentation
An internet gateway is a horizontally scaled, redundant, and highly
available VPC component that allows communication between instances in
your VPC and the internet. It therefore imposes no availability risks
or bandwidth constraints on your network traffic.
Here is a highly available architecture image showing NAT GW per AZ and Internet GW as a VPC resource
Image source: https://aws.amazon.com/quickstart/architecture/vpc/
I'm new to AWS VPC setup for 3-tier web application. I created a VPC with subnet 10.0.0.0/16, and what is the good best practice to do the subnet segmentation in AWS VPC for 3 tier web application? I have ELB with 2 EC2 instances, and RDS and S3 in the backend.
Please advise!! Thanks.
A common pattern you will find is:
VPC with /16 (eg 10.0.0.0/16, which gives all 10.0.x.x addresses)
Public subnets with /24 (eg 10.0.5.0/24, which gives all 10.0.5.x addresses)
Private subnets with /23 (eg 10.0.6.0/23, which gives all 10.0.6.x and 10.0.7.x) -- this is larger because most resources typically go into private subnets and it's a pain to have to make it bigger later
Of course, you can change these above sizes to whatever you want within allowed limits.
Rather than creating a 3-tier structure, consider a 2-tier structure:
1 x Public Subnet per AZ for the Load Balancer (and possibly a Bastion/Jump Box)
1 x Private Subnet per AZ for everything else — application, database, etc.
There is no need to have apps and databases in separate private subnets unless you are super-paranoid. You can use Security Groups to configure the additional layer of security without using separate subnets. This means less IP addresses are wasted (eg in a partially-used subnet).
Of course, you could just use Security Groups for everything and just use one tier, but using private subnets gives that extra level of assurance that things are configured safely.
The way we do it:
We create a VPC that is a /16, e.g. 172.20.0.0/16. Do not use the default VPC.
Then we create a set of subnets for each application “tier”.
Public - Anything with a public IP. Load balancers and NAT gateways are pretty much the only thing here.
Web DMZ - Web servers go here. Anything that is a target for the load balancer.
Data - Resources responsible for storing and retrieving data. RDS instances, EC2 database servers, ElastiCacahe instances
Private - For resources that are truly isolated from Internet traffic. Management and reporting. You may not need this in your environment.
Subnets are all /24. One subnet per availability zone. So there would be like 3 Public subnets, 3 Web DMZ subnets, etc.
Network ACLs control traffic between the subnets. Public subnets can talk to Web DMZ. Web DMZ can talk to Data. Data subnets can talk to each other to facilitate clustering. Private subnets can’t talk to anybody.
I intentionally keep things very coarse in the Network ACL. I do not restrict specific ports/applications. We do that at the Security Group level.
Pro tip: Align the Subnets groups on a /20 boundary to simplify your Network ACLs rules. Instead of listing each data subnet individually, you can just list a single /20 which encompasses all data subnets.
Some people would argue this level of separation is excessive. However I find it useful because it forces people to think about the logical structure of the application. It guards against someone doing something stupid with a Security Group. It’s not bulletproof, but it is a second layer of defense. Also, we sometimes get security audits from customers that expect to see a traditional structure like you would find in an on-prem network.
Can we have two elastic beanstalk applications along with RDS database instances in one VPC.
What i am trying to do is the following:
1) EB App1: Web tier which hands web request
2) EB App2: Worker (application) Tier that performs the processing
3) RDS Db Instances: This is the database tier.
I want to put each of the above in one VPC and assign them within there separate VPC Security Groups in this VPC, hence controlling the flow of traffic between all the tiers.
Also, can i span these security groups into multiple availability zones.
Does beanstalk and VPC allow this above proposed design and is it a good design or am i overcomplicating stuff.
Thanks
MHF
I want to put each of the above in one VPC and assign them within
there separate VPC Security Groups in this VPC, hence controlling the
flow of traffic between all the tiers.
Yes of course, that's exactly how a VPC works.
Also, can i span these security groups into multiple availability
zones.
Security groups are VPC wide, they automatically span all availability zones. You would have to create Security Group rules that specify a specific subnet's IP range to narrow a security group to a specific availability zone.
Does beanstalk and VPC allow this above proposed design and is it a
good design or am i overcomplicating stuff.
Yes, this is just a normal AWS VPC configuration. What you are proposing is the normal way to do this.