Visualizing Kubernetes with Generated Diagrams

Kevin Howell

Red Hat

Agenda

• Kubernetes primer
• Exploring resources without diagrams
• k8sviz
• kubectl graph
• Advice

First I’ll frame why diagrams are useful for kubernetes and then we’ll look at a couple of tools for diagramming k8s:

• k8sviz
• kubectl graph

And then I’ll wrap up with some general thoughts.

About Me

• Principal Software Engineer at Red Hat
• console.redhat.com subscriptions Tech Lead
• Raleigh, NC
• @kahowell@mastodon.social
• https://kahowell.net

First up a bit about me. Java, Quarkus, OpenShift, Tekton

Kubernetes Primer

• Declarative interface
• API resources
• Distributed workloads
• Container-centric

1. In kubernetes you declare the desired state of things and then kubernetes is responsible to “make it so”.
2. Declarations are in the language of API resources. Every resource has a group (namespace), kind, and name.
3. Because kubernetes is all about running fault-tolerant, distributed workloads, it’s often necessary to have multiple instances of a given resource.
4. Kubernetes is container-centric. Often, we work at an abstraction level above individual containers though.

To elaborate on the last couple of points, distributed workloads and layers of abstraction increase the cognitive complexity of dealing with Kubernetes applications.

Abstractions in Kubernetes

1. Deployment is a common resource type, responsible for running a workload and performing rolling updates.
2. Deployments are implemented with one or more replicasets, responsible for keeping a number of copies of a workload running.
3. Replicasets schedule pods, one or more containers running together on the same node.

Navigating Relationships - CLI

Get owner:

kubectl get $type/$name \
  -o template \
  --template \
  '{{(index .metadata.ownerReferences 0).kind}}/'\
'{{(index .metadata.ownerReferences 0).name}}'

… and repeat

It’s one thing to conceptually understand those abstractions, and another to explore them in a running application.

First, we’ll talk about the how relationships are available through the API (and consequently the CLI), every resource optionally has an ownerReferences field in the metadata that points to its parent or parents.

You can query this for a given resource by using this kubectl command.

Navigating Relationships - GUI

Owner Links in OpenShift/OKD

If you’re using a Kubernetes service with a web UI, you can often follow the trail using hyperlinks.

The Pattern for Diagrams

• Query Resources
• Draw a graph
  • k8s resources, relationships
  • as nodes and edges

Given we’re navigating a graph, it’s hopefully obvious that we can draw a diagram of that graph, and that it can be automated.

Conceptually, it’s pretty simple:

• query some resources
• lay them out in a graph.

k8sviz

https://github.com/mkimuram/k8sviz

Installation

git clone https://github.com/mkimuram/k8sviz
cd k8sviz
make build  # requires golang
cp -R icons bin/

Usage

# output a graphviz source file
bin/k8sviz -n keycloak-system -t dot -o keycloak.dot
# generate a png image
bin/k8sviz -n keycloak-system -t png -o keycloak.png

k8sviz - Results

keycloak diagram

This works, but it’s hard to read a tall diagram in a wide presentation.

k8sviz - Results (edited)

keycloak diagram - edited for LR layout & bigger font

There we go!

Here you can see at a glance: * A deployment for the keycloak operator * StatefulSets for Postgres and an example keycloak deployment * the replicasets, pods, services, and ingress instances underneath those objects

k8sviz - Ideas for Improvment

• packaging
• layout, font options
• filters
• custom resource support
• offline support (helm charts, kustomize)

• It would be ideal if this were packaged in Fedora or Ubuntu
• If there were better layout and font options/defaults, would be helpful
• Sometimes you don’t need to see all the resources
• Sometimes you have all you need locally to get a representation of an application in k8s

kubectl-graph

https://github.com/steveteuber/kubectl-graph

Installation

# assumes krew already installed
# https://krew.sigs.k8s.io/docs/user-guide/setup/install/
kubectl krew install graph

Usage

# kubectl graph $type0,$type1,...
kubectl graph keycloak,deployments,replicasets,statefulsets

kubectl-graph - Graphviz

kubectl graph rendering of keycloak resources.

kubectl-graph - Mermaid (edited for LR layout)

graph LR
  60a85292-052f-210d-178a-3829b4f551bb((keycloak-...)):::Namespace
  5e4e0c9f-db23-447a-8e91-0e3e2d6b0b20((keycloak-...)):::ReplicaSet
  a3e07832-474c-4042-983e-d098a760fb4d((example-kc-0)):::Pod
  6bbe31ab-4d6b-4911-9dae-a311bae1dc87((example-kc)):::StatefulSet
  e07c0e8b-1c22-bfad-3ecd-a1cff0450321((keycloak)):::Container
  8e77e145-c83d-2ddb-6123-72cf7664cd35((keycloak-...)):::Container
  c7468ee8-d08e-10f0-6c57-e8c5a2b7b319((api.crc.t...)):::Cluster
  8d1b02ce-8247-449b-888c-5ab3770e7f07((keycloak-...)):::Deployment
  0ba2caef-915f-41d8-b742-0c18cbaae490((keycloak-...)):::Pod
  c5bf27c6-b79a-48f1-b1e6-bf3392b9ed8a((postgresq...)):::Pod
  97945256-8cc4-4e25-9f24-dfe2eac17b48((postgresq...)):::StatefulSet
  93893b75-19b3-dcd9-6301-416922554914((postgresq...)):::Container
  f9b274dc-00d1-4767-954f-3f9c343f5547((example-kc)):::Keycloak
  0ba2caef-915f-41d8-b742-0c18cbaae490 -- Container --> 8e77e145-c83d-2ddb-6123-72cf7664cd35
  97945256-8cc4-4e25-9f24-dfe2eac17b48 -- Pod --> c5bf27c6-b79a-48f1-b1e6-bf3392b9ed8a
  c5bf27c6-b79a-48f1-b1e6-bf3392b9ed8a -- Container --> 93893b75-19b3-dcd9-6301-416922554914
  c7468ee8-d08e-10f0-6c57-e8c5a2b7b319 -- Namespace --> 60a85292-052f-210d-178a-3829b4f551bb
  60a85292-052f-210d-178a-3829b4f551bb -- Deployment --> 8d1b02ce-8247-449b-888c-5ab3770e7f07
  60a85292-052f-210d-178a-3829b4f551bb -- Keycloak --> f9b274dc-00d1-4767-954f-3f9c343f5547
  8d1b02ce-8247-449b-888c-5ab3770e7f07 -- ReplicaSet --> 5e4e0c9f-db23-447a-8e91-0e3e2d6b0b20
  6bbe31ab-4d6b-4911-9dae-a311bae1dc87 -- Pod --> a3e07832-474c-4042-983e-d098a760fb4d
  a3e07832-474c-4042-983e-d098a760fb4d -- Container --> e07c0e8b-1c22-bfad-3ecd-a1cff0450321
  5e4e0c9f-db23-447a-8e91-0e3e2d6b0b20 -- Pod --> 0ba2caef-915f-41d8-b742-0c18cbaae490
  f9b274dc-00d1-4767-954f-3f9c343f5547 -- StatefulSet --> 6bbe31ab-4d6b-4911-9dae-a311bae1dc87
  60a85292-052f-210d-178a-3829b4f551bb -- StatefulSet --> 97945256-8cc4-4e25-9f24-dfe2eac17b48

kubectl-graph - Ideas for Improvment

• alternative packaging (rpm, deb)
• icons
• layout, font options
• edge choices

• It would be ideal if this were packaged in Fedora or Ubuntu
• If there were better layout and font options/defaults, would be helpful
• Sometimes you don’t need to see all the resources
• Using resource types as edges is an interesting choice for more dense diagrams, but I’d like options.

Advice

• Don’t be afraid to edit diagrams
• Try multiple tools/formats

Red Hat Developer

• no-cost subscription for individuals
• free sandbox environments
• https://developers.redhat.com

Q&A

Thanks for attending!

• @kahowell@mastodon.social
• https://kahowell.net

Note

Title slide Photo by orbtal media on Unsplash

red.ht/SCALE2024