The other day I came across an interesting repo on github, KubeDiagrams.

What this repo does is generate Kubernetes architecture diagrams from Kubernetes manifest files…nice!

Deploying applications to Kubernetes can get complicated fast…especially with stateful applications such as SQL Server.

So having the ability to easily generate diagrams is really helpful…because we all should be documenting everything, right? 🙂

Plus I’m rubbish at creating diagrams!

So let’s have a look at how this works. First, install the dependencies via pip: –

pip install pyyaml
pip install diagrams

And install graphviz: –

sudo apt install graphviz

Great, now pull down the repo: –

git clone https://github.com/philippemerle/KubeDiagrams.git

And we’re good to go! So here’s an example manifest file to deploy a SQL Server statefulset to Kubernetes: –

apiVersion: v1
kind: Namespace
metadata:
  name: mssql
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: mssql-sc
provisioner: docker.io/hostpath
reclaimPolicy: Delete
volumeBindingMode: Immediate
---
apiVersion: v1
kind: Service
metadata:
  name: mssql-headless
  namespace: mssql
spec:
  clusterIP: None
  selector:
    name: mssql-pod
  ports:
    - name: mssql-port
      port: 1433
      targetPort: 1433
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mssql-statefulset
  namespace: mssql
spec:
  serviceName: "mssql-headless"
  replicas: 1
  podManagementPolicy: Parallel
  selector:
    matchLabels:
      name: mssql-pod
  template:
    metadata:
      labels:
        name: mssql-pod
    spec:
      securityContext:
        fsGroup: 10001
      containers:
        - name: mssql-container
          image: mcr.microsoft.com/mssql/server:2022-CU16-ubuntu-20.04
          ports:
            - containerPort: 1433
              name: mssql-port
          env:
            - name: MSSQL_PID
              value: "Developer"
            - name: ACCEPT_EULA
              value: "Y"
            - name: MSSQL_AGENT_ENABLED
              value: "1"
            - name: MSSQL_SA_PASSWORD
              value: "Testing1122"
          resources:
            requests:
              memory: "1024Mi"
              cpu: "500m"
            limits:
              memory: "2048Mi"
              cpu: "2000m"
          volumeMounts:
            - name: sqlsystem
              mountPath: /var/opt/mssql
            - name: sqldata
              mountPath: /opt/sqlserver/data
            - name: sqllog
              mountPath: /opt/sqlserver/log
  volumeClaimTemplates:
    - metadata:
        name: sqlsystem
        namespace: mssql
      spec:
        accessModes:
         - ReadWriteOncePod
        storageClassName: mssql-sc
        resources:
          requests:
            storage: 25Gi
    - metadata:
        name: sqldata
        namespace: mssql
      spec:
        accessModes:
         - ReadWriteOncePod
        storageClassName: mssql-sc
        resources:
          requests:
            storage: 25Gi
    - metadata:
        name: sqllog
        namespace: mssql
      spec:
        accessModes:
         - ReadWriteOncePod
        storageClassName: mssql-sc
        resources:
          requests:
            storage: 25Gi
---
apiVersion: v1
kind: Service
metadata:
  name: mssql-service
  namespace: mssql
spec:
  ports:
  - name: mssql-ports
    port: 1433
    targetPort: 1433
  selector:
    name: mssql-pod
  type: LoadBalancer

I’m using Docker Desktop here (hence the provisioner: docker.io/hostpath in the storage class). What this’ll create is a namespace, storage class, headless service for the statefulset, the statefulset itself, three persistent volume claims, and a load balanced service to connect to SQL.

Quite a lot of objects for a simple SQL Server deployment, right? (ahh I know it’s a statefulset, but you know what I mean)

So let’s point KubeDiagrams at the manifest: –

./kube-diagrams mssql-statefulset.yaml

And here’s the output!

Pretty cool, eh?

I noticed a couple of quirks. The docs say it’ll work with any version 3 install of python. I had 3.8 installed but had to upgrade to 3.9.

Also I had to add namespace: mssql to the PVCs in the statefulset, otherwise KubeDiagrams threw a warning: –

Error: ‘sqlsystem/mssql/PersistentVolumeClaim/v1’ resource not found!
Error: ‘sqldata/mssql/PersistentVolumeClaim/v1’ resource not found!
Error: ‘sqllog/mssql/PersistentVolumeClaim/v1’ resource not found

But other than those, it works really well and is a great way to visualise objects in Kubernetes.

Massive thank you to the creator, Philippe Merle!

Thanks for reading!