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Helm Chart

Sample helm chart based on step4 manifests.


  • helm
brew install kubernetes-helm

Getting started with minikube

# setup secret for TLS certificates
# this commands will generate self signed server certificate and key: server.pem, server.key
# key and cert are stored in Secret object named `demoapp-puma-tls`.
# you can confirm this object by `kubectl describe secret demoapp-puma-tls`
export MINIKUBE_IP=$(minikube ip)
export COMMON_NAME=demoapp-puma.${MINIKUBE_IP}
openssl req -new -x509 -nodes -keyout server.key -days 3650 \
  -subj "/CN=${COMMON_NAME}" \
  -extensions v3_req \
  -config <(cat openssl.conf | sed s/\${COMMON_NAME}/$COMMON_NAME/) > server.pem
kubectl create secret tls demoapp-puma-tls --key server.key --cert server.pem

# setup helm's server module a.k.a Tiller
helm init --wait

# install all objects by helm chart and wait until the deployment complete
helm upgrade staging . --install --wait --set${COMMON_NAME}

# open demoapp in browser
open https://demoapp-puma.$(minikube ip)

# cleanup all objects
helm delete staging --purge

# uninstall Tiller
helm reset

See also Makefile. There are shorthand tasks for the above operations.

make kubectl-create-secret-tls
make helm-upgrade
make open
make helm-delete
make helm-reset

Deploy new rails image includes migration

For example, when you create new migration like this:

# Move to RAILS_ROOT
cd ../../

# Create new migration for example
./bin/rails g migration AddLiksToMessage likes:integer
./bin/rails db:migrate

To build new rails image, deploy, and execute rake db:migrate on k8s, run the following commands:

# Move to RAILS_ROOT
cd ../../

# Build new image as demoapp:0.0.2
eval $(minikube docker-env) && docker build . -t demoapp:0.0.2

# Update all puma deployments. Only one of them will execute rails db:migrate.
# and wait until the deployment is completed
kubectl set image deploy/demoapp-puma puma=demoapp:0.0.2
helm upgrade staging . --install --wait \
  --set${COMMON_NAME} \
  --set rails.image.tag=0.0.2

Rails's migration is exclusive controlled by RDBMS's lock system at least when executed on MySQL or PostgreSQL. So to execute rails db:migrate safely, all you need is just ignore ActiveRecord::ConcurrentMigrationError. Please refer to bin/start-puma and db:try_migrate for details.

See also Makefile. There are shorthand tasks for the above operations.

make TAG=0.0.2 minikube-docker-build
make TAG=0.0.2 deploy

To reduce --set parameter, update your values.yaml.