I have recently started exploring kuberenetes and done with practical implementation of pods,services and replication Controller on google cloud. I have some doubts over service and network access .
First, Where is the service deployed which will work as load balancer for group of pods ?
Second, does the request to access an application running in pod using a service load balancer go through master or direct to minions nodes ?
A service proxy runs on each node on the cluster. From inside the cluster, when you make a request to a service IP, it is intercepted by the service proxy and routed to a pod matching the label selector for the service. If you have specified an external load balancer for your service, the load balancer will pick a node to send the request to, at which point it will be captured by the proxy and directed to an appropriate pod. If you are using public IPs, then your router will send the request to the node with the public IP where it will be captured by the proxy and directed to an appropriate pod.
If you followed by description, you can see that service requests do not go through the master. They bounce through a proxy running on the nodes.
As an aside, there is also a proxy running on the master, which you can use to reach nodes, services, pods, but this proxy isn't in the packet path for services that you create within the cluster.
Related
As far as I know, Instance Management and the Controller have the same functions, which managing NGINX Plus and the Instances. but it does not make more sense.
So my question is
What are the differences between Instance Management and Controller?
What is Ingress Controller?
Nginx Instance Management: NGINX Instance Manager empowers you to
Automate configuration and monitoring using APIs.
For example, if you have multiple servers using Nginx then in Nginx Plus service provides a dashboard where all the events can be monitored, Including spikes on specific events, Or think as one of the servers has not been updated from having multiple VM, monitor the list of inventory. To achieve nginx-agant needs to install along with Nginx server on the host.
Ensure your fleet of NGINX web servers and proxies have fixes for
active CVEs
Seamlessly integrate with third‑party monitoring solutions such as
Prometheus and Grafana for insights
Nginx Controller: NGINX Controller is cloud‑agnostic and includes a set of enterprise‑grade services that give you a clear line of sight to apps in development, test, or production. With per‑app analytics, you gain new insights into app performance and reliability so you can pinpoint performance issues before they impact production.
Example: To enable the ingress you did need an Ingress Controller to enabled first.
Nginx Ingress: Each LoadBalancer service requires its own load balancer with its own public IP address, whereas an Ingress only requires one, even when providing access to dozens of services. When a client sends an HTTP request to the Ingress, the host and path in the request determine which service the request is forwarded to.
For example Google Kubernetes Controller
I'm currently working on copying AWS EKS cluster to Azure AKS.
In our EKS we use external Nginx with proxy protocol to identify the client real IP and check if it is whitelisted in our Nginx.
In AWS to do so we added to the Kubernetes service annotation aws-load-balancer-proxy-protocol to support Nginx proxy_protocol directive.
Now the day has come and we want to run our cluster also on Azure AKS and I'm trying to do the same mechanism.
I saw that AKS Load Balancer hashes the IPs so I removed the proxy_protocol directive from my Nginx conf, I tried several things, I understand that Azure Load Balancer is not used as a proxy but I did read here:
AKS Load Balancer Standard
I tried whitelisting IPs at the level of the Kubernetes service using the loadBalancerSourceRanges api instead on the Nginx level.
But I think that the Load Balancer sends the IP to the cluster already hashed (is it the right term?) and the cluster seem to ignore the ips under loadBalancerSourceRanges and pass them through.
I'm stuck now trying to understand where I lack the knowledge, I tried to handle it from both ends (load balancer and kubernetes service) and they both seem not to cooperate with me.
Given my failures, what is the "right" way of passing the client real IP address to my AKS cluster?
From the docs: https://learn.microsoft.com/en-us/azure/aks/ingress-basic#create-an-ingress-controller
If you would like to enable client source IP preservation for requests
to containers in your cluster, add --set controller.service.externalTrafficPolicy=Local to the Helm install
command. The client source IP is stored in the request header under
X-Forwarded-For. When using an ingress controller with client source
IP preservation enabled, SSL pass-through will not work.
More information here as well: https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip
You can use the real_ip and geo modules to create the IP whitelist configuration. Alternatively, the loadBalancerSourceRanges should let you whitelist any client IP ranges by updating the associated NSG.
my k8s master node has Public network IP, and worker node deploy in private net. worker node can connect to master but master cannot connect to worker node.
I have tested that can deploy a pod by kubectl, the pod running on worker node and master can watch pod status. but when I deploy a ingress, and access the ingress on master node, traffic cannot go to worker node.
I use flannel network.
I have tried use ssh tunnel, but it hard to management
I don't know if there are some suggests, thanks.
If you are deployed in a cloud environment, the most likely cause is incorrect firewall settings or route configurations. However, ingress configuration errors also may appear to look like infrastructure problems at times.
The Ingress will redirect your requests to the different services that it is registered with. The endpoint health is also monitored and requests will only be sent to active and healthy endpoints. My troubleshooting flow is as follows:
Hit an unregistered path on your url and check if you get the default backend response. If no, then your ingress controller may not be correctly set up (whether it be domain name, access rules, or just configuration). If yes, then your ingress controller should be correctly set up, and this is a problem with the Ingress definition or backend.
Try hitting your registered path on your url. If you get a 504 gateway timeout, then your endpoint is accepting the request, but not responding correctly. You can follow the target pod logs to figure out whether it is behaving properly.
If you get a 503 Service Unavailable, then your service might be down or deemed unhealthy by the ingress. In this case, you should definitely verify that your pods are running properly.
Check your nginx-ingress-controller logs to see how the requests are being redirected and what the internal responses are.
All your nodes and master should have communication with each other, without this you are going to have problems on cluster functionalities.
The ingress creates a load balancer pointing to your nodes machines.
Why your master cannot connect to your nodes?
Give a check on:
https://kubernetes.io/docs/concepts/architecture/master-node-communication/
I want to use Nginx to load balance a kubernetes deployment.
The deployment is part of a service. It contains pod which can be scaled. I want NGINX to be part of the service without being scaled.
I know that I can use NGINX as an external load balancer by configuring it with external dns resolver. With that it can get the IP of the pods scaled and apply its own load balanced rules.
Is it possible to make NGINX part of the service? Then how to do the DNS resolution to the pods? In that case, which pods the service name is refered to?
I would like to avoid the declaration of two services to keep a single definition of the setup which represent a microservice.
More generally, how can I declare in a same service:
a unit which is scaled
a backend, not scaled
a database, not scaled
Thanks all
You can't have NGINX as part of the service. Service doesn't contain any pods, deployment does. It sounds like you want an ingress service, that would be a load balancer any and all services on the cluster
EDIT:
An ingress controller in essence is a deployment of NGINX exposed publicly as a service acting as a load balancer/fan out. The deployment scans your cluster for ingress resources and reconfigures NGINX to forward requests to appropriate services.
Typically people deploy a single controller that acts as the load balancer for all of your microservices. You can fan out based on DNS, URI, other headers and so on. You can also do TLS termination, add basic auth to specific services, it's even possible to splice in NGINX config snippets directly into the ingress resources.
I am trying to set up a HTTP load balancer for my Meteor app on google cloud. I have the application set up correctly, and I know this because I can visit the IP given in the Network Load Balancer.
However, when I try and set up a HTTP load balancer, the health checks always say that the instances are unhealthy (even though I know they are not). I tried including a route in my application that returns a status 200, and pointing the health check towards that route.
Here is exactly what I did, step by step:
Create new instance template/group for the app.
Upload image to google cloud.
Create replication controller and service for the app.
The network load balancer was created automatically. Additionally, there were two firewall rules allowing HTTP/HTTPS traffic on all IPs.
Then I try and create the HTTP load balancer. I create a backend service in the load balancer with all the VMs corresponding to the meteor app. Then I create a new global forwarding rule. No matter what, the instances are labelled "unhealthy" and the IP from the global forwarding rule returns a "Server Error".
In order to use HTTP load balancing on Google Cloud with Kubernetes, you have to take a slightly different approach than for network load balancing, due to the current lack of built-in support for HTTP balancing.
I suspect you created your service in step 3 with type: LoadBalancer. This won't work properly because of how the LoadBalancer type is implemented, which causes the service to be available only on the network forwarding rule's IP address, rather than on each host's IP address.
What will work, however, is using type: NodePort, which will cause the service to be reachable on the automatically-chosen node port on each host's external IP address. This plays more nicely with the HTTP load balancer. You can then pass this node port to the HTTP load balancer that you create. Once you open up a firewall on the node port, you should be good to go!
If you want more concrete steps, a walkthrough of how to use HTTP load balancers with Container Engine was actually recently added to GKE's documentation. The same steps should work with normal Kubernetes.
As a final note, now that version 1.0 is out the door, the team is getting back to adding some missing features, including native support for L7 load balancing. We hope to make it much easier for you soon!