Kubernetes Ingress Controller for AWS
This is an ingress controller for Kubernetes — the open-source container deployment, scaling, and management system — on AWS. It runs inside a Kubernetes cluster to monitor changes to your ingress resources and orchestrate AWS Load Balancers accordingly.
This ingress controller uses the EC2 instance metadata of the worker node where it's currently running to find the additional details about the cluster provisioned by Kubernetes on top of AWS. This information is used to manage AWS resources for each ingress objects of the cluster.
- Uses CloudFormation to guarantee consistent state
- Automatic discovery of SSL certificates
- Automatic forwarding of requests to all Worker Nodes, even with auto scaling
- Automatic cleanup of unnecessary managed resources
- Support for internet-facing and internal load balancers
- Support for multiple Auto Scaling Groups
- Support for instances that are not part of Auto Scaling Group
- Can be used in clusters created by Kops, see our deployment guide for Kops
- Support Multiple TLS Certificates per ALB (SNI).
<v0.8.0 to >=v0.8.0
v0.8.0 added certificate verification check to automatically ignore
self-signed and certificates from internal CAs. The IAM role used by the controller
now needs the
is no longer needed and can be removed from the role.
<v0.7.0 to >=v0.7.0
v0.7.0 deletes the annotation
zalando.org/aws-load-balancer-ssl-cert-domain, which we do not
consider as feature since we have SNI enabled ALBs.
<v0.6.0 to >=v0.6.0
v0.6.0 introduced support for Multiple TLS Certificates per ALB
(SNI). When upgrading your ALBs will automatically be aggregated to a single
ALB with multiple certificates configured.
It also adds support for attaching single EC2 instances and multiple
AutoScalingGroups to the ALBs therefore you must ensure you have the correct
instance filter defined before upgrading. The default filter is
tag:kubernetes.io/cluster/<cluster-id>=owned tag-key=k8s.io/role/node see
How it works for more information on how to configure this.
<v0.5.0 to >=v0.5.0
v0.5.0 introduced support for both
load balancers. For this change we had to change the naming of the
CloudFormation stacks created by the controller. To upgrade from v0.4.* to
v0.5.0 no changes are needed, but since the naming change of the stacks
migrating back down to a v0.4.* version will not be non-disruptive as it will
be unable to manage the stacks with the new naming scheme. Deleting the stacks
manually will allow for a working downgrade.
<v0.4.0 to >=v0.4.0
In versions before v0.4.0 we used AWS Tags that were set by CloudFormation automatically to find some AWS resources. This behavior has been changed to use custom non cloudformation tags.
In order to update to v0.4.0, you have to add the following tags to your AWs Loadbalancer SecurityGroup before updating:
Additionally you must ensure that the instance where the ingress-controller is
running has the clusterID tag
ClusterID=<cluster-id> before v0.4.0).
This controller is used in production since Q1 2017. It aims to be out-of-the-box useful for anyone running Kubernetes. Jump down to the Quickstart to try it out—and please let us know if you have trouble getting it running by filing an Issue. If you created your cluster with Kops, see our deployment guide for Kops
As of this writing, it's being used only in small production use cases at Zalando, and is not yet battle-tested. We're actively seeking devs/teams/companies to try it out and share feedback so we can make improvements.
Why We Created This Ingress Controller
The maintainers of this project are building an infrastructure that runs Kubernetes on top of AWS at large scale (for nearly 200 delivery teams), and with automation. As such, we're creating our own tooling to support this new infrastructure. We couldn't find an existing ingress controller that operates like this one does, so we created one ourselves.
We're using this ingress controller with Skipper, an HTTP router that Zalando has used in production since Q4 2015 as part of its front-end microservices architecture. Skipper's also open source and has some outstanding features, that we documented here. Feel free to use it, or use another ingress of your choosing.
How It Works
This controller continuously polls the API server to check for ingress resources. It runs an infinite loop. For each cycle it creates load balancers for new ingress resources, and deletes the load balancers for obsolete/removed ingress resources.
This is achieved using AWS CloudFormation. For more details check our CloudFormation Documentation
The controller will not manage the security groups required to allow access from the Internet to the load balancers. It assumes that their lifecycle is external to the controller itself.
During startup phase EC2 filters are constructed as follows:
CUSTOM_FILTERSenvironment variable is set, it is used to generate filters that are later used to fetch instances from EC2.
CUSTOM_FILTERSenvironment variable is not set or could not be parsed, then default filters are
<cluster-id>is determined from EC2 tags of instance on which Ingress Controller pod is started.
CUSTOM_FILTERS is a list of filters separated by spaces. Each filter has a form of
name=value where name is one
of names that are recognized by the EC2 API (you can find list here)
and value is value of a filter. For example:
tag-key=testwill filter instances that has tag named
vpc-id=vpc-1a2b3c4dwill filter instances that belong to specific VPC.
- Default filter
tag:kubernetes.io/cluster/<cluster-id>=owned tag-key=k8s.io/role/nodefilters instances that has tag
ownedand have tag named
Every poll cycle EC2 is queried with filters that were constructed during startup.
Each new discovered instance is scanned for Auto Scaling Group tag. Each Target
Group created by this Ingress controller is then added to each known Auto Scaling Group.
Each Auto Scaling Group information is fetched only once when first node of it is discovered for first time.
If instance does not belong to Auto Scaling Group (does not have
aws:autoscaling:groupName tag) it is stored in separate list of
Single Instances. On each cycle instances on this list are registered as targets in all Target Groups managed by this controller.
If call to get instances from EC2 did not return previously known Single Instance, it is deregistered from Target Group and removed from list of Single Instances.
Call to deregister instances is aggregated so that maximum 1 call to deregister is issued in poll cycle.
On startup, the controller discovers the AWS resources required for the controller operations:
The Security Group
Lookup of the
kubernetes.io/cluster/<cluster-id>tag of the Security Group matching the clusterID for the controller node and
kubernetes:applicationmatching the value
kube-ingress-aws-controlleror as fallback for
aws:cloudformation:logical-idmatching the value
IngressLoadBalancerSecurityGroup(only clusters created by CF).
Subnets are discovered based on the VPC of the instance where the controller is running. By default it will try to select all subnets of the VPC but will limit the subnets to one per Availability Zone. If there are many subnets within the VPC it's possible to tag the desired subnets with the tags
kubernetes.io/role/elb(for internet-facing ALBs) or
kubernetes.io/role/internal-elb(for internal ALBs). Subnets with these tags will be favored when selecting subnets for the ALBs. Additionally you can tag EC2 subnets with
kubernetes.io/cluster/<cluster-id>, which will be prioritized. If there are two possible subnets for a single Availability Zone then the first subnet, lexicographically sorted by ID, will be selected.
Creating Load Balancers
When the controller learns about new ingress resources, it uses the hosts specified in it to automatically determine the most specific, valid certificates to use. The certificates has to be valid for at least 7 days. An example ingress:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: test-app spec: rules: - host: test-app.example.org http: paths: - backend: serviceName: test-app-service servicePort: main-port
The Application Load Balancer created by the controller will have both an HTTP listener and an HTTPS listener. The latter will use the automatically selected certificates.
As a second option you can specify the Amazon Resource Name (ARN) of the desired certificate with an annotation like the one shown here:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: myingress annotations: zalando.org/aws-load-balancer-ssl-cert: arn:aws:acm:eu-central-1:123456789012:certificate/f4bd7ed6-bf23-11e6-8db1-ef7ba1500c61 spec: rules: - host: test-app.example.org http: paths: - backend: serviceName: test-app-service servicePort: main-port
You can select the Application Load Balancer Scheme with an annotation like the one shown here:
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: myingress annotations: zalando.org/aws-load-balancer-scheme: internal spec: rules: - host: test-app.example.org http: paths: - backend: serviceName: test-app-service servicePort: main-port
You can only select from
internet-facing (default) and
By default the ingress-controller will aggregate all ingresses under as few
Application Load Balancers as possible (unless running with
-disable-sni-support). If you like to provision an Application Load Balancer
that is unique for an ingress you can use the annotation
The new Application Load Balancers have a custom tag marking them as managed load balancers to differentiate them from other load balancers. The tag looks like this:
`kubernetes:application` = `kube-ingress-aws-controller`
They also share the
kubernetes.io/cluster/<cluster-id> tag with other resources from the cluster where it belongs.
Deleting load balancers
When the controller detects that a managed load balancer for the current cluster doesn't have a matching ingress resource anymore, it deletes all the previously created resources.
Building a Binary
To build a binary for the Linux operating system, simply run
Building a Docker Image
To create a Docker image instead, execute
make build.docker. You can then push your Docker image to the Docker
registry of your choice.
registry.opensource.zalan.do/teapot/kube-ingress-aws-controller:latest as a publicly usable Docker image
built from this codebase. You can deploy it with 2 easy steps:
- Replace the placeholder for your region inside the example YAML, for ex.,
- Use kubectl to execute the command
kubectl apply -f deploy/ingress-controller.yaml
Running multiple instances
In some cases it might be useful to run multiple instances of this controller:
- Isolating internal vs external traffic
- Using a different set of traffic processing nodes
- Using different frontend routers (e.g.: Skipper and Traefik)
You can use the flag
-controller-id to set a token that will be used to isolate resources between controller instances.
This value will be used to tag those resources.
If you don't pass an ID, the default
kube-ingress-aws-controller will be used.
Usually you would want to combine this flag with
ingress-class-filter so different types of ingresses are associated with the different controllers.
Target and Health Check Ports
By default the port 9999 is used as both health check and target port. This means that Skipper or any other traffic router you're using needs to be listening on that port.
If you want to change the default ports, you can control it using the
The controller used to have only the
-health-check-port flag available, and would use the same port as health check and the target port.
Those ports are now configured individually. If you relied on this behavior, please include the
-target-port in your configuration.
Trying it out
The Ingress Controller's responsibility is limited to managing load balancers, as described above. To have a fully functional setup, additionally to the ingress controller, you can use Skipper to route the traffic to the application. The setup follows what's described here.
You can deploy
skipper as a
DaemonSet using another example YAML by executing the following command:
kubectl apply -f deploy/skipper.yaml
To complete the setup, you'll need to fulfill some additional requirements regarding security groups and IAM roles; more info here.
To have convenient DNS names for your application, you can use the Kubernetes-Incubator project, external-dns. It's not strictly necessary for this Ingress Controller to work, though.
We welcome your contributions, ideas and bug reports via issues and pull requests; here are those Contributor guidelines again.
Check our MAINTAINERS file for email addresses.
We welcome your security reports please checkout our SECURITY.md.
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