add initcontainers support

[laszlocph]

Init Containers are now available 🚀

initContainers:
- name: setup
  image: node
  tag: latest
  command: "cp /conf/setup.sh / && cd / && chmod +x setup.sh && ./setup.sh"

To mount a volume just for the init-container, use the init- prefix.

volumes:
- name: init-configuration
  existingConfigMap: setup
  path: /conf

To mount a shared volume between the init and main container, use the shared- prefix.

- name: shared-static-files
  emptyDir: true 
  path: /usr/share/nginx/html

Using init-containers to build and run static websites

The example bellow uses Hugo.

• Uses an init container to setup Hugo, clone the source from git and build the site
• The built site is then copied to a shared volume
• Nginx serves the built site from the volume

helm repo add onechart https://chart.onechart.dev

cat << EOF > hugo.yaml
volumes:
- name: init-hugo
  fileName: setup_hugo.sh
  path: /hugo.conf
  subPath: setup_hugo.sh
  fileContent: |
    #!/usr/bin/env bash
    # Pre-reqs
    apt update && apt install -y wget git

    # Setting up Hugo 
    wget https://github.com/gohugoio/hugo/releases/download/v0.111.3/hugo_0.111.3_Linux-64bit.tar.gz &&
    tar -xzf hugo_0.111.3_Linux-64bit.tar.gz &&
    chmod +x hugo &&
    mv hugo /usr/local/bin && cd / &&
    
    # Getting and building Hugo site source
    git clone https://github.com/gimlet-io/hugo-site.git &&
    cd hugo-site && hugo &&
    
    # Copying the built Hugo site to the shared volume for serving with Nginx
    mkdir -p /usr/share/nginx/html && cp -r ./public/. /usr/share/nginx/html
- name: shared-static-files
  emptyDir: true
  path: /usr/share/nginx/html 
initContainers:
- name: setup
  image: debian
  tag: stable-slim
  command: |
    cp /hugo.conf/setup_hugo.sh . &&
    chmod +x setup_hugo.sh && 
    ./setup_hugo.sh
image:
  repository: nginx
  tag: 1.23.3
EOF

helm template my-hugo-site onechart/onechart -f hugo.yaml > manifest.yaml
kubectl apply -f manifest.yaml

kubectl port-forward svc/my-hugo-site 8000:80

[laszlocph]

Looks good.

Few formatting comments and a question on what will happen if the initContainer does not contain a command.

[laszlocph]

The codebase uses the following format for multiline strings:

mystring: |
  this
  is
  a multilline

i was surprised to see this working.

[YoucefGuichi]

yes first i was doing it as multiline string, then i found that you are using qoute on the command for the main container, it was more convenient for me with less mess, what do you think ?

[laszlocph]

Looks good, thanks!