drzippie / Chart-post-install-hook

Use Post Install hook to make modification in third party services.

Chart-post-install-hook

Are you using Helm Charts to deploy you application in Kubernetes. If you have dependency on other services like mongodb, postgresql or redis and you want to modify it to add more users or create multiple database. You can use Kubernetes Jobs with "helm.sh/hook": post-install

In this example I am creating 2 users in MongoDb deployment using post-install hook. See the create-user.yaml and mongodb-setup-scripts.yaml file.

Prerequisites Details

• Kubernetes 1.6+

Chart Details

This chart will do the following:

• Deploy Express-Mongo-CRUD Application
• Deploy a MongoDB database using the stable/mongodb chart

Installing the Chart

To install the chart with the release name Node App:

$ helm install --name hook ./

To pull docker images from Private Docker Registry

# Create a kubectl secret to pull from private docker registry
$ kubectl create secret docker-registry regsecret --docker-server=https://my.docker.registry --docker-username=<USER> --docker-password=<API_KEY> --docker-email=<EMAIL>

Once created, Use it to install Charts

$ helm install --name hook --set imagePullSecrets=regsecret ./

Configuration

The following table lists the configurable parameters of the Node App chart and their default values.

Parameter	Description	Default
initContainerImage	Init Container Image	alpine:3.6
replicaCount	Replica count for Node App deployment	1
imagePullSecrets	Docker registry pull secret
ingress.enabled	If true, Node App Ingress will be created	false
ingress.annotations	Node App Ingress annotations	{}
ingress.hosts	Node App Ingress hostnames	[]
ingress.tls	Node App Ingress TLS configuration (YAML)	[]
db.name	Mongodb Database name	test
db.adminUser	Mongodb Database Admin user	admin
db.adminPassword	Mongodb Database Admin password	password
db.nodeUser	Mongodb Database Node user	node
db.nodePassword	Mongodb Database Node password	password
image.repository	Container repository	jainishshah17/express-mongo-crud
image.tag	Container tag	1.0.0
image.pullPolicy	Container pull policy	IfNotPresent
service.type	Node App service type	LoadBalancer
service.internalPort	Node App service internal port	3000
service.externalPort	Node App service external port	80
persistence.mountPath	Node App persistence volume mount path	"/var/log/app"
persistence.enabled	Node App persistence volume enabled	true
persistence.existingClaim	Provide an existing PersistentVolumeClaim	nil
persistence.storageClass	Storage class of backing PVC	nil (uses alpha storage class annotation)
persistence.size	Node App persistence volume size	2Gi
resources.requests.memory	Node App initial memory request
resources.requests.cpu	Node App initial cpu request
resources.limits.memory	Node App memory limit
resources.limits.cpu	Node App cpu limit

Specify each parameter using the --set key=value[,key=value] argument to helm install.

Ingress and TLS

To get Helm to create an ingress object with a hostname, add these two lines to your Helm command:

helm install --name hook \
  --set ingress.enabled=true \
  --set ingress.hosts[0]="jainish.company.com" \
  --set service.type=NodePort \
  --set nginx.enabled=false \
  ./

If your cluster allows automatic creation/retrieval of TLS certificates (e.g. kube-lego), please refer to the documentation for that mechanism.

To manually configure TLS, first create/retrieve a key & certificate pair for the address(es) you wish to protect. Then create a TLS secret in the namespace:

kubectl create secret tls chart-example-tls --cert=path/to/tls.cert --key=path/to/tls.key

Include the secret's name, along with the desired hostnames, in the Node App Ingress TLS section of your custom values.yaml file:

  ingress:
    ## If true, Node Aapp Ingress will be created
    ##
    enabled: true

    ## Node Aapp Ingress hostnames
    ## Must be provided if Ingress is enabled
    ##
    hosts:
      - jainish.domain.com
    annotations:
      kubernetes.io/tls-acme: "true"
    ## Node Aapp Ingress TLS configuration
    ## Secrets must be manually created in the namespace
    ##
    tls:
      - secretName: chart-example-tls
        hosts:
          - jainish.domain.com

Useful links

• Source of Example Application