Consider that I have built a complex Kubernetes deployment/workload consisting of deployments, stateful sets, services, operators, CRDs with specific configuration etc… The workload/deployment was created by individual commands (kubectl create, helm install…)…
1-) Is there a way to dynamically (not manually) generate a script or a special file that describes the deployment and that could be used to redeploy/reinstall my deployment without going into each command one by one again.
2-) Is there a domain specific language (DSL) or something similar through which one can describe a Kubernetes deployment independently from the final target kubernetes cluster target, whether GKE, AWS, Azure, or on premises … kind of write once deploy anywhere…
Thanks.
I think Kustomize and Helm are your best bet. We can write the helm chart as a template and decide which template to use with Go-Templating and conditions.
For example, look at the below configuration file which has a few conditions.
apiVersion: apps/v1
kind: Deployment
metadata:
name: {{ .Values.appName }}
namespace: {{ .Values.namespace }}
spec:
selector:
matchLabels:
app: {{ .Values.appName }}
replicas: {{ .Values.replicaCount }}
template:
metadata:
annotations:
labels:
app: {{ .Values.appName }}
spec:
containers:
- name: {{ .Values.appName }}
image: {{ .Values.image.repository }}:{{ .Values.image.tag }}
imagePullPolicy: {{ .Values.image.pullPolicy }}
{{- if .Values.hasSecretVolume }}
volumeMounts:
- name: {{ .Values.appName }}-volume-sec
mountPath: {{ .Values.secretVolumeMountPath }}
{{- end}}
{{- if or .Values.env.configMap .Values.env.secrets }}
envFrom:
{{- if .Values.env.configMap }}
- configMapRef:
name: {{ .Values.appName }}-env-configmap
{{- end }}
{{- if .Values.env.secrets }}
- secretRef:
name: {{ .Values.appName }}-env-secret
{{- end }}
{{- end }}
ports:
- containerPort: {{ .Values.containerPort }}
protocol: TCP
{{- if .Values.railsContainerHealthChecks}}
{{ toYaml .Values.railsContainerHealthChecks | indent 8 }}
{{- end}}
{{- if .Values.hasSecretVolume }}
volumes:
- name: {{ .Values.appName }}-volume-sec
secret:
secretName: {{ .Values.appName }}-volume-sec
{{- end}}
{{- if .Values.imageCredentials}}
imagePullSecrets:
- name: {{.Values.imageCredentials.secretName}}
{{- end}}For instance, this condition checks for Secret volume and mounts it.
{{- if .Values.hasSecretVolume }}
In case you are interested in helm and generic templating, you can refer to this medium blog: https://medium.com/srendevops/helm-generic-spring-boot-templates-c9d9800ddfee