I am looking to map out various network connections between pods in a namespace to understand which pod is talking to which other pods. Is there a way to query the etcd to get this information?
There are many tools to visualize k8s topology.
In order of Github stars:
Cockpit:
Cockpit Project — Cockpit Project Cockpit makes GNU/Linux discoverable. See your server in a web browser and perform system tasks with a mouse. It’s easy to start containers, administer storage, configure networks, and inspect logs.
Weave Scope (Github: weaveworks/scope) is a troubleshooting and monitoring tool for Docker and Kubernetes clusters. It can automatically generate applications and infrastructure topologies which can help you to identify application performance bottlenecks easily. You can deploy Weave Scope as a standalone application on your local server/laptop, or you can choose the Weave Scope Software as a Service (SaaS) solution on Weave Cloud. With Weave Scope, you can easily group, filter or search containers using names, labels, and/or resource consumption. :
spekt8/spekt8: Visualize your Kubernetes cluster in real time :
SPEKT8 is a new visualization tool for your Kubernetes clusters. It automatically builds logical topologies of your application and infrastructure, which enable your SRE and Ops team to intuitively understand, monitor, and control your containerized, microservices based application. Simply deploy our containerized application directly into your Kubernetes cluster.
KubeView (Github: benc-uk/kubeview: Kubernetes cluster visualiser and graphical explorer )
KubeView displays what is happening inside a Kubernetes cluster, it maps out the API objects and how they are interconnected. Data is fetched real-time from the Kubernetes API. The status of some objects (Pods, ReplicaSets, Deployments) is colour coded red/green to represent their status and health.
Kubernetes Topology Graph:
Provides a simple force directed topology graph for kubernetes items.
You can try to use Weave Scope to make a graphical map of your Kubernetes cluster.
It will generates a map of your process, containers and hosts in real time. You can also get logs from containers and run some diagnostic commands via WEB-UI.
To install on Kubernetes you can run:
kubectl apply -f "https://cloud.weave.works/k8s/scope.yaml?k8s-version=$(kubectl version | base64 | tr -d '\n')"
After launch you don't need to configure anything, Scope will listen you pods and network and make a map of you network.
Related
I’ve build a bare-metal multi-node, multi-server Kubernetes cluster and this is my first experience.
The cluster is built across many servers; each server contains a set of nodes.
The connection is done over public ip addresses on the LAN.
I run deployments on the cluster and it’s working.
But I want to expose a service over the external network.
If I were using Minikube, I would use a LoadBalancer to expose the service externally.
Troubleshooting:
I am thinking about using an ingress-controller or a NodePort Service as a solution to access the pods-network.
I tried to expose a NodePort service, but I didn't get an external ip.
I am asking if someone could help me set a running hello-world, but choosing the right architecture for this bare-metal cluster.
Thank you.
I suggest using MetalLB which is a LoadBalancer for bare metal clusters.
Also you could combine this with a bare metal Ingress controller like Nginx.
Regarding Nginx you can find more details here.
I have successfully used this combination as well as with a wildcard domain (e.g *.mydomain) pointing to one of the cluster IPs. This allows to define as many combinations as you like to point to different services deployed on the cluster (e.g. service1.mydomain, service2.mydomain, etc.).
What I would also suggest is installing Helm as this would greatly help you with deployments. You can find a lot of charts for most of the widely spread services and it gives you the ability to configure them easily. Also it is quite a good practice to create charts for your future services as well for good maintenance and customization.
Nodeport service helps here
In bare metal lets you have host1,master as cluster members.
If you create node port service on node port ex : 31000
you can use http://host1IP:31000/ for QA
What I am doing right now:
I own many VPS which I use to deploy applications with Docker compose, most of the machines come from different subnets and have a public static IP address.
For each new application I would pick a random VPS, assign the new application's subdomain's DNS with the VPS' IP address and deploy my application in this VPS behind an Nginx proxy (jwilder Nginx).
This approach is in my opinion very comfortable since jwilder's Nginx does almost the work for me and I only have to assign the correct DNS.
What I want to achieve:
For the purpose of learning, I would like to take the machines and make a Kubernetes cluster out of them, so I could learn more about this technology. My idea is that I only have to assign new subdomain's DNS to one single point, which also plays the role of a load balancer and pass the traffic to corresponding pods.
To redirect traffic to a new application I only have to configure the load balancer.
My problem:
I know this question is not very precise since I don't know a lot of Kubernetes. Moreover, my servers are not from a cloud provider like Google or AWS and I, therefore, can not use their solutions. They are not even from a single cloud provider, most of them are of my university and some are from a private cloud provider.
Could anybody tell me how can I achieve this?
I think the answer is kubeadm, you can install it on your own pc or vm.
It is gonna create a single control-plane cluster which could be joined by other of your vms and create a kubernetes cluster.
kubeadm helps you bootstrap a minimum viable Kubernetes cluster that conforms to best practices
kubeadm is designed to be a simple way for new users to start trying Kubernetes out, possibly for the first time, a way for existing users to test their application on and stitch together a cluster easily, and also to be a building block in other ecosystem and/or installer tool with a larger scope.
Your cluster pods will communicate via CNI.
CNI was created as a minimal specification, built alongside a number of network vendor engineers to be a simple contract between the container runtime and network plugins
I'm trying to figure out a proper way to implement active/passive failover between replicas of service with Docker swarm mode.
The service will hold a valuable in-memory state that cannot be lost, that's why I need multiple replicas of it. The replicas will internally implement Raft so that only the replica which is active ("leader") at a given moment will accept requests from clients.
(If you're unfamiliar with Raft: simply put, it is a distributed consensus algorithm, which helps implement active/passive fault-tolerant cluster of replicas. According to Raft, the active replica - the leader - replicates changes in its data to passive replicas - the followers. The only leader accepts requests from clients. If the leader fails, a new leader is elected among the followers).
As far as I understand, Docker will guarantee that a specified number of replicas are up and running, but it will balance incoming requests among all of the replicas, in the active/active manner.
How can I tell Docker to route requests only to the active replica, but still guarantee that all replicas are up?
One option is routing all requests through an additional NGINX container, and updating its rules each time a new leader is elected. But that will be an additional hop, which I'd like to avoid.
I'm also trying to avoid external/overlapping tools such as consul or kubernetes, in order to keep the solution as simple as possible. (HAProxy is not an option because I need a Linux/Windows portable solution). So currently I'm trying to understand if this can be done with Docker swarm mode alone.
Another approach I came across is returning a failing health check from passive replicas. It does the trick with kubernetes according to this answer, but I'm not sure it will work with Docker. How does the swarm manager interpret failing health checks from task containers?
I'd appreciate any thoughts.
Active Passive replica can be achieved by having below deployment mode:
mode: global
With this port of the corresponding service is open, i.e., service is accessible via any the nodes in the swarm, but container will be running only on particular node.
Ref: https://docs.docker.com/compose/compose-file/#mode
Example:
VAULT-HA with Consul Backend docker stack file:
https://raw.githubusercontent.com/gtanand1994/VaultHA/master/docker-compose.yml
Here, Vault and Nginx containers will be seen only in one node in the swarm, but Consul containers (having mode: replicated) will be present on all the nodes of swarm.
But as I said before, VAULT, and NGINX services are available via 'any_node_ip:corresponding_port_number'
So Kubernetes has a pretty novel network model, that I believe is based on what it perceives to be a shortcoming with default Docker networking. While I'm still struggling to understand: (1) what it perceives the actual shortcoming(s) to be, and (2) what Kubernetes' general solution is, I'm now reaching a point where I'd like to just implement the solution and perhaps that will clue me in a little better.
Whereas the rest of the Kubernetes documentation is very mature and well-written, the instructions for configuring the network are sparse, largely incoherent, and span many disparate articles, instead of being located in one particular place.
I'm hoping someone who has set up a Kubernetes cluster before (from scratch) can help walk me through the basic procedures. I'm not interested in running on GCE or AWS, and for now I'm not interested in using any kind of overlay network like flannel.
My basic understanding is:
Carve out a /16 subnet for all your pods. This will limit you to some 65K pods, which should be sufficient for most normal applications. All IPs in this subnet must be "public" and not inside of some traditionally-private (classful) range.
Create a cbr0 bridge somewhere and make sure its persistent (but on what machine?)
Remove/disable the MASQUERADE rule installed by Docker.
Some how configure iptables routes (again, where?) so that each pod spun up by Kubernetes receives one of those public IPs.
Some other setup is required to make use of load balanced Services and dynamic DNS.
Provision 5 VMs: 1 master, 4 minions
Install/configure Docker on all 5 VMs
Install/configure kubectl, controller-manager, apiserver and etcd to the master, and run them as services/daemons
Install/configure kubelet and kube-proxy on each minion and run them as services/daemons
This is the best I can collect from 2 full days of research, and they are likely wrong (or misdirected), out of order, and utterly incomplete.
I have unbridled access to create VMs in an on-premise vCenter cluster. If changes need to be made to VLAN/Switches/etc. I can get infrastructure involved.
How many VMs should I set up for Kubernetes (for a small-to-medium sized cluster), and why? What exact corrections do I need to make to my vague instructions above, so as to get networking totally configured?
I'm good with installing/configuring all the binaries. Just totally choking on the network side of the setup.
For a general introduction into kubernetes networking, I found http://www.slideshare.net/enakai/architecture-overview-kubernetes-with-red-hat-enterprise-linux-71 pretty helpful.
On your items (1) and (2): IMHO they are nicely described in https://github.com/kubernetes/kubernetes/blob/master/docs/admin/networking.md#docker-model .
From my experience: What is the Problem with the Docker NAT type of approach? Sometimes you need to configure e.g. into the software all the endpoints of all nodes (172.168.10.1:8080, 172.168.10.2:8080, etc). in kubernetes you can simply configure the IP's of the pods into each others pod, Docker complicates it using NAT indirection.
See also Setting up the network for Kubernetes for a nice answer.
Comments on your other points:
1.
All IPs in this subnet must be "public" and not inside of some traditionally-private (classful) range.
The "internal network" of kubernetes normally uses private IP's, see also slides above, which uses 10.x.x.x as example. I guess confusion comes from some kubernetes texts that refer to "public" as "visible outside of the node", but they do not mean "Internet Public IP Address Range".
For anyone who is interested in doing the same, here is my current plan.
I found the kube-up.sh script which installs a production-ish quality Kubernetes cluster on your AWS account. Essentially it creates 1 Kubernetes master EC2 instance and 4 minion instances.
On the master it installs etcd, apiserver, controller manager, and the scheduler. On the minions it installs kubelet and kube-proxy. It also creates an auto-scaling group for the minions (nice), and creates a whole slew of security- and networking-centric things on AWS for you. If you run the script and it fails creating the AWS S3 bucket, create a bucket of the same exact name manually and then re-run the script.
When the script is finished you will have Kubernetes up and running and ready for near-production usage (I keep saying "near" and "production-ish" because I'm too new to Kubernetes to know what actually constitutes a real deal productionalized cluster). You will need the AWS CLI installed and configured with a user that has full admin access to your AWS account (it goes ahead and creates IAM roles, etc.).
My game plan will be to:
Get comfortable working with Kubernetes on AWS
Keep hounding the Kubernetes team on Slack to help me understand how Kubernetes works under the hood
Reverse engineer the kube-up.sh script so that I can get Kubernetes running on premise (vCenter)
Blog about this process
Update this answer with a link to said blog.
Give me some time and I'll follow through.
I am going through an article weave net driver and was trying my hands on it. I was able to use the default weavemesh driver for container-to-container communication on single host. The issue comes when i try to create multiple networks using weave network driver plugin. I get the following error.
[ankit#local-machine]$ docker network create -d weave netA
Error response from daemon: failed to parse pool request for address space "GlobalDefault" pool "" subpool "": cannot find address space GlobalDefault (most likely the backing datastore is not configured)
Now, as i understand from docker documentation at Getting Started with Docker Multi-host Networking , It needs a key value store to be configured. I was wondering if my understanding is correct? Is there any way to create multiple networks over weave network to achieve network isolation. I want to be able to segregate network traffic for one container from another container running on the same box.
There is a new weave 1.4 plugin docker networking without cluster store plugin announcement recently which says it supports docker networking without external cluster store. how does it exactly work. its not very clear if it could be used to create multiple networks over weave.
This issue asked:
Did you start the docker daemon with --cluster-store?
You need to pass peers ips to weave launch-router $peers when starting docker with --cluster-store and --cluster-advertise.
The doc mentions:
The Weave plugin actually provides two network drivers to Docker
one named weavemesh that can operate without a cluster store and
one named weave that can only work with one (like Docker’s overlay driver).
Hence the need to Set up a key-value store first.
If you are using the weave plugin, your understanding is correct.
PR 1738 has more on the new weave 1.4+ ability to operate without a keystore with the weavemesh driver. Its doc does mention:
If you do create additional networks using the weavemesh driver, containers attached to them will be able to communicate with containers attached to weave; there is no isolation between those networks.
But PR 1742 is still open "Allow user to specify a subnet range for each docker host".