Kubernetes Services Helm Charts

This package contains Helm charts for deploying your applications on Kubernetes clusters with Helm.

This package is a part of the Gruntwork Infrastructure as Code Library, a collection of reusable, battle-tested, production ready infrastructure code. Read the Gruntwork Philosophy document to learn more about how Gruntwork builds production grade infrastructure code.

What is in this Package

This repo provides a Gruntwork IaC Package and has the following folder structure:

charts: This folder contains the main implementation code for this Package, broken down into multiple standalone charts.
examples: This folder contains examples of how to use the Charts.
test: Automated tests for the Charts and examples.

The following charts are available in this package:

k8s-service: Deploy a set of Docker containers as a Kubernetes Deployment, which provisions a Pod with a Controller that will handle replication and self-healing capabilities for the application. Additionally, expose the Deployment behind a Service for a consistent endpoint to access the application.

How do you install the charts in this Package?

The charts in this Package are distributed in the Gruntwork Helm Repo. You can access these charts by adding the Gruntwork Helm Repo to your client:

$ helm repo add gruntwork https://helmcharts.gruntwork.io

Then, you can access any of the charts under the gruntwork name. For example, you can find all the Gruntwork charts by searching for gruntwork:

$ helm search gruntwork

In general, each of the charts document the required and optional input values in the corresponding values.yaml file. You can access the values.yaml of a Chart either by inspecting this repository, or using the helm inspect command. For example, to see the values of the k8s-service chart, you can run:

$ helm inspect values gruntwork/k8s-service

Once you know what values the chart requires, you can install the chart by defining your own values.yaml file with the required values defined. Then, you can install the chart to your Kubernetes cluster using helm install:

$ helm install -f values.yaml gruntwork/k8s-service

See the helm install help text for more configuration options.

What is Kubernetes?

Kubernetes is an open source container management system for deploying, scaling, and managing containerized applications. Kubernetes is built by Google based on their internal proprietary container management systems (Borg and Omega). Kubernetes provides a cloud agnostic platform to deploy your containerized applications with built in support for common operational tasks such as replication, autoscaling, self-healing, and rolling deployments.

You can learn more about Kubernetes from the official documentation.

What is Helm?

Helm is a package and module manager for Kubernetes that allows you to define, install, and manage Kubernetes applications as reusable packages called Charts. Helm provides support for official charts in their repository that contains various applications such as Jenkins, MySQL, and Consul to name a few. Gruntwork uses Helm under the hood for the Kubernetes modules in this package.

Helm consists of two components: the Helm Client, and the Helm Server (Tiller)

What is the Helm Client?

The Helm client is a command line utility that provides a way to interact with Tiller. It is the primary interface to installing and managing Charts as releases in the Helm ecosystem. In addition to providing operational interfaces (e.g install, upgrade, list, etc), the client also provides utilities to support local development of Charts in the form of a scaffolding command and repository management (e.g uploading a Chart).

What is the Helm Server?

The Helm Server (Tiller) is a component of Helm that runs inside the Kubernetes cluster. Tiller is what provides the functionality to apply the Kubernetes resource descriptions to the Kubernetes cluster. When you install a release, the helm client essentially packages up the values and charts as a release, which is submitted to Tiller. Tiller will then generate Kubernetes YAML files from the packaged release, and then apply the generated Kubernetes YAML file from the charts on the cluster.

How do you run applications on Kubernetes?

There are three different ways you can schedule your application on a Kubernetes cluster. In all three, your application Docker containers are packaged as a Pod, which are the smallest deployable unit in Kubernetes, and represent one or more Docker containers that are tightly coupled. Containers in a Pod share certain elements of the kernel space that are traditionally isolated between containers, such as the network space (the containers both share an IP and thus the available ports are shared), IPC namespace, and PIDs in some cases.

Pods are considered to be relatively ephemeral disposable entities in the Kubernetes ecosystem. This is because Pods are designed to be mobile across the cluster so that you can design a scalable fault tolerant system. As such, Pods are generally scheduled with Controllers that manage the lifecycle of a Pod. Using Controllers, you can schedule your Pods as:

Jobs, which are Pods with a controller that will guarantee the Pods run to completion. See the k8s-job chart for more information.
Deployments behind a Service, which are Pods with a controller that implement lifecycle rules to provide replication and self-healing capabilities. Deployments will automatically reprovision failed Pods, or migrate Pods to healthy nodes off of failed nodes. A Service constructs a consistent endpoint that can be used to access the Deployment. See the k8s-service chart for more information.
Daemon Sets, which are Pods that are scheduled on all worker nodes. Daemon Sets schedule exactly one instance of a Pod on each node. Like Deployments, Daemon Sets will reprovision failed Pods and schedule new ones automatically on new nodes that join the cluster. See the k8s-daemon-set chart for more information.

Who maintains this Package?

This Package and its Charts are maintained by Gruntwork. If you are looking for help or commercial support, send an email to support@gruntwork.io.

Gruntwork can help with:

Setup, customization, and support for this Module.
Packages and Modules for other types of infrastructure, such as VPCs, Docker clusters, databases, and continuous integration.
Packages and Modules that meet compliance requirements, such as HIPAA.
Consulting & Training on AWS, Terraform, and DevOps.

How do I contribute to this Package?

Contributions are very welcome! Check out the Contribution Guidelines for instructions.

How is this Package versioned?

This Module follows the principles of Semantic Versioning. You can find each new release, along with the changelog, in the Releases Page.

During initial development, the major version will be 0 (e.g., 0.x.y), which indicates the code does not yet have a stable API. Once we hit 1.0.0, we will make every effort to maintain a backwards compatible API and use the MAJOR, MINOR, and PATCH versions on each release to indicate any incompatibilities.

License

Please see LICENSE and NOTICE for how the code in this repo is licensed.

dvdvgs82/helm-kubernetes-services