Helm Package Standards📜

This document describes the technical guidelines that should be in place when building a Helm chart and integrating it with Big Bang.

Helm Package Versioning Scheme📜

Big Bang packages follow a standard semantic versioning scheme for both the package tag and the chart version. The package tag will always be in line with the chart version (not the appVersion). To distinguish between BigBang specific changes within the semantic version of the upstream chart, a suffix of -bb.# will be added to all charts and tags.

For example, for the upstream istio-operator pinned at version 1.7.3, the Big Bang version (with the modified values.yaml for an Iron Bank image) will be tagged 1.7.3-bb.0. If in the same istio-operator release, Big Bang requires chart modifications (such as to support imagePullSecrets), then the new version becomes 1.7.3-bb.1.

For another example in using the kube-prometheus-stack, the upstream is versioned at 12.2.2, meaning BigBang’s initial fork will be 12.2.2-bb.0. Future additions, such as adding VirtualServices for the ingresses, bumps to the -bb.# will happen in sequence every time BigBang updates the chart within the same version.

Big Bang Values File📜

In the values.yaml file here, each package should have its own region at .package_name if its in Core or .addons.package_name.
User Interface:
- If there exists need for ingress traffic into the package, the package should create a VirtualService conditional on the existence of istio.enabled being set to true. This value should default to false. The BigBang chart should set this true for all packages.
- There should be a region under the package for configuring SSO that looks like this when there are multiple packages.
```
  sso:
    enabled: false
    kiali:
        client_id: kiali
        client_secret: "change_me"
    jaeger:
        client_id: jaeger
        client_secret: "change_me"
```
or like this if there is a single user interface:
```
  sso:
    enabled: false
    client_id: twistlock_id
    client_secret: "change_me"
```
If sso is enabled and a value is not provided in the SSO configuration of the package, it should default to the top level SSO configuration.

Database Connections:

The BigBang chart should prevent the use of a database bundled as part of the package chart by default, and warn if an end user uses one anyways.
There should be a database section under the package configuration that matches the following section.

database:
  # Entering connection info will enable external database and will auto-create any required secrets.
  host: ""
  port: ""
  username: ""
  password: ""
  database: ""
  type: "" # Optional. One of mysql, mssql, postgres, mongo if ther

Monitoring:
- Charts should expect a value monitoring.enabled to be set by the BigBang chart to conditionally create monitoring components (e.g., ServiceMonitors and/or PodMonitors). This value should default to false.

Secrets📜

The BigBang chart should make an ImagePullSecret in the namespace the package will be deployed in.
If the package chart cannot accept credentials (e.g., for databases) as a value, then the BigBang chart should make the secret with values passed into BigBang and pass the Secret to the package chart by name.

Big Bang Helm Release📜

The ImagePullSecret name as private-registry should be configured in each package’s chart/template/{package}/values.yaml to be passed in to each Package.

Common Values📜

Every object in a package should have the following labels:

Key	Description	Example
app.kubernetes.io/name	The name of the application	`argocd`
app.kubernetes.io/instance	The unique name identifying the instance of an application. Name of the `HelmRelease`	`argocd`
app.kubernetes.io/version	The chart version that manages the object	`1.0.1-bb.10`
app.kubernetes.io/component	the component within the architecture	`database`

Each package shall have the ability to add labels to all objects via a top level commonLabels map. The labels that will be passed in from the Big Bang chart shall include at least:

Key	Description	Example
app.kubernetes.io/part-of	the name of a higher level application this one is part of	`bigbang`
app.kubernetes.io/managed-by	the tool being used to manage the operation of an application	`flux`
app.kubernetes.io/bigbang-version	The version of bigbang deployed	`1.0.7`

which would be passed in via:

commonLabels:
  app.kubernetes.io/part-of: bigbang
  app.kubernetes.io/managed-by: flux
  app.kubernetes.io/bigbang-version: 1.6.0

Big Bang Package Readme Generation📜

Follow this guide for package readme.md generation.

Note the Big Bang package README.md is separate from the README.md included as part of the upstream chart. See ArgoCD for an example, Big Bang package README.md vs upstream chart README.md.

Each package value in values.yaml should have a comment descriptor above the value. We generate the package README.md using a script that expects this format. The README.md will contain a table with default configurations and descriptors pulled from the comments.

This is a comment for the value below📜

enabled: false

This comment describes the purpose of the configurable value below📜

strategy: scalable

Kubernetes Objects📜

These requirements for the kubernetes components come from the Kubernetes STIG, Kubesec.io and other best practices.

Resource Limits and Requests set for cpu and memory and they are Guaranteed QoS
Containers are not run in privileged mode
Read Only Root File System is set to true
Containers are not run as root
runAsUser >= 1000
Each deployment/daemonset/statefulset should use its own service account with least privilege permission set
HostPath volumes are not allowed
All resources contain the Kubernetes Common Labels
All containers contain health and liveness checks