container.training/slides/k8s/create-chart.md

Creating a chart

• We are going to show a way to create a very simplified chart

• In a real chart, lots of things would be templatized

  (Resource names, service types, number of replicas...)

.exercise[

• Create a sample chart:

  helm create dockercoins
  

• Move away the sample templates and create an empty template directory:

  mv dockercoins/templates dockercoins/default-templates
  mkdir dockercoins/templates
  

]

---

Exporting the YAML for our application

• The following section assumes that DockerCoins is currently running

.exercise[

• Create one YAML file for each resource that we need: .small[

  
    while read kind name; do
      kubectl get -o yaml $kind $name > dockercoins/templates/$name-$kind.yaml
    done <<EOF
    deployment worker
    deployment hasher
    daemonset rng
    deployment webui
    deployment redis
    service hasher
    service rng
    service webui
    service redis
    EOF
  

  ]

]

---

Testing our helm chart

.exercise[

• Let's install our helm chart! (dockercoins is the path to the chart)

  helm install dockercoins
  

]

--

• Since the application is already deployed, this will fail:
  Error: release loitering-otter failed: services "hasher" already exists

• To avoid naming conflicts, we will deploy the application in another namespace

---

Switching to another namespace

• We can create a new namespace and switch to it

  (Helm will automatically use the namespace specified in our context)

• We can also tell Helm which namespace to use

.exercise[

• Tell Helm to use a specific namespace:

  helm install dockercoins --namespace=magenta
  

]

---

Checking our new copy of DockerCoins

• We can check the worker logs, or the web UI

.exercise[

• Retrieve the NodePort number of the web UI:

  kubectl get service webui --namespace=magenta
  

• Open it in a web browser

• Look at the worker logs:

  kubectl logs deploy/worker --tail=10 --follow --namespace=magenta
  

]

Note: it might take a minute or two for the worker to start.