Dependencies

Helm & Tiller

First of all you need to install the Helm client following the next instructions:

curl https://raw.githubusercontent.com/kubernetes/helm/master/scripts/get > get_helm.sh
chmod 700 get_helm.sh
./get_helm.sh

For deploys is also needed the server portion of Helm, Tiller (it talks to a remote Kubernetes cluster). To install it into the cluster, simply runs:

helm init

For more information take a look at: Install Helm

Packages

To use this repository as a k8s charts repository for deploy your apps you have to configure helm adding it:

helm repo add apsl https://raw.githubusercontent.com/APSL/kubernetes-charts/master/packages/

Check that it has been added.

helm repo list

NAME     	URL
stable   	https://kubernetes-charts.storage.googleapis.com
incubator	https://kubernetes-charts-incubator.storage.googleapis.com/
local    	http://127.0.0.1:8879/charts
apsl     	https://raw.githubusercontent.com/APSL/kubernetes-charts/master/packages/

Structure of repository

kubernetes-charts/    
├── packages/                           # Reult folder where construct temporaly packages before be installed.
|    ...
|    ├── index.yaml                     # Contains the configuration for a django app deployment.
|    ├── django-nginx-uwsgi-0.1.1.tgz   # Django package. It includes nginx, uwsgi, redis, varnish packages.
|    ├── uwsgi-0.1.1.tgz                # Uwsgi package.
|    └── varnish-0.1.0.tgz              # Varnish package.
...
├── django/                             # Contains the configuration for a django app deployment.
|    ├── .helmignore                    # List of patterns to ignore when build the package.
|    ├── Chart.yaml                     # A YAML file containing information about the chart.
|    ├── requirements.yaml              # List of required charts and their overriden configuration.
|    ├── values.yaml                    # The default configuration values for this chart
|    ├── charts/                        # Include all dependency packages
|    |                                  # IMPORTANT: No commit packages into.
|    └── templates/                     # A directory of templates that, when combined with values.
|        └── _helpers.tpl               # Difinition of template variables.
|                                       # Note that not require templates because this chart only encapsulate
|                                       # dependencies.
└── uwsgi/                              # Contains the configuration for a uwsgi deployment.
     ├── charts/                        # Folder that contains built packages for the dependecies of this chart.
     |                                  # IMPORTANT: No commit packages into, will be auto-generated.
     ├── .helmignore                    # List of patterns to ignore when build the package.
     ├── Chart.yaml                     # A YAML file containing information about the chart.
     ├── requirements.yaml              # List of required charts and their overriden configuration.
     ├── values.yaml                    # The default configuration values for this chart
     └── templates/                     # A directory of templates that, when combined with values.
         ├── NOTES.txt                  # A plain text file containing short usage notes (rendered with Go Template engine)
         ├── _helpers.tpl               # Definition of template variables.
         ├── deployment.yaml            # Structure of deployment for this chart.
         ├── secrets.yaml               # Base secrets for the chart.
         └── service.yaml               # Structure of service for this chart.

Take a look to The Chart File Structure to get acquainted to chart structure.

The django-nginx-uwsgi chart is a generic Helm chart for deploy a Django application with a simple architecture:

How to

This section will try to explain you how to use this repository to deploy your applications.

How to deploy a chart over Kubernetes?

Will show you the procedure to deploy a Django application using this charts.

This example we'll deploy an app called demo, suposing you satisfy all dependencies.

Deploy the Django application.

helm install PACKAGE --version VERSION --namespace NAMESPACE --name RELEASE_NAME -f VALUES

PACKAGE → The path to stored package.
VERSION → The exact version of the package to install. If it is not set the last version will be deployed.
--namespace NAMESPACE → The namespace that will be create on Google Cloud Platform and will be user with in the deployment.
--name RELEASE_NAME → It must has a different value to namespace. It is used in the deployment and dependencies deployments.
-f VALUES → Path to the file where are all values that overrides the Helm chart, for example SECRET_KEY or DATABASE_PASSWORD, etc.

helm install apsl/django-nginx-uwsgi --version 0.1.1 --namespace demo --name r-demo -f your_demo_app_values.yaml

How to test your deployment before apply it on your K8s cluster?

Helm Template is a plugin used to render the resultant deployment of your chart.

Install:

helm plugin install https://github.com/technosophos/helm-template

Use it:

helm template -n NAMESPACE -r RELEASE_NAME -f VALUES --notes CHART > output.yaml

-n NAMESPACE → The namespace used with in deployment.
-r RELEASE_NAME → The release name used with in deployment.
-f VALUES → Override specific values for application.
--notes → Render the NOTES.txt file chart's dependencies notes.
CHART → Location path to the chart.

helm template -n demo -r r-demo -f your_demo_app_values.yaml --notes . > ~/k8s-deployment.yaml

Contributors

Developing new Helm charts

There are some notes and some command line instructions that can be useful as a guide how to develop new charts.

To create a new chart:

helm create CHART

CART → Full path to destination chart.

helm create django-nginx-uwsgi

After develop your template chart, you can validate if your chart is valid running a lint.

helm lint django-nginx-uwsgi

Building package

If you contribute creating niw Charts or improving the existent you should do this:

Serve your packages locally
Update dependent locally repositories your Chart
Generate your package
Regenerate index-yaml

To simplify all this tasks, you only have to execute this:

make helm-up & \
make helm-packages && \
helm repo index packages

NOTE: Its possible see some non-liveness message using make command to build packages. If the message is like "No requirements found in ~/kubernetes-charts/nginx-uwsgi/charts" ignore it. It is because the commnand script try to get dependencies of all packages even if it has not charts (the dependency folder).

Use case:

We will generate a new chart packagedemo_:

Create the chart

helm create packagedemo

Serve built local packages:

cd packages
helm serve

Build all dependent packages:

helm package -u -d packages uwsgi
helm package -u -d packages nginx
helm package -u -d packages packagedemo

or use the Makefile commands:

make helm-packages

Generate index

helm repo index packages