README.md

iX Official Catalog

A curated collection of TrueNAS SCALE enhanced Helm charts.

TrueNAS SCALE Chart Structure

A TrueNAS SCALE chart repository differs slightly in directory structure from upstream repos in that it includes an app version directory.

A TrueNAS SCALE chart also has three additional files an app-readme.md file that provides a high level overview display in the TrueNAS SCALE UI and a questions.yaml file defining questions to prompt the user with and an item.yaml file outlining item specific details.

There are 2 directories charts and test, each representing a train. Chart releases created from catalog items in a specific train cannot be moved to another train. Currently only the charts train can be used inside the UI.

charts/ix-chart/<chart version>/
  app-readme.md            # TrueNAS SCALE Specific: Readme file for display in TrueNAS SCALE UI
  charts/                  # Directory containing dependency charts
  Chart.yaml               # Required Helm chart information file
  questions.yaml           # TrueNAS SCALE Specific: File containing questions for TrueNAS SCALE UI
  README.md                # Optional: Helm Readme file (will be rendered in TrueNAS SCALE UI as well)
  templates/               # A directory of templates that, when combined with values.yml will generate K8s YAML
  values.yaml              # The default configuration values for this chart

See the upstream Helm chart developer reference for a complete walk through of developing charts.

To convert an upstream chart to take advantage of TrueNAS SCALE enhanced UX, first create an item.yaml file. This file among other catalog item information provides a list of categories that this chart fits into. This helps users navigate and filtering when browsing the catalog UI.

$ cat charts/ix-chart/item.yaml
categories:
  - generic
icon_url: "http://ix_url"

After that create app-readme.md file.

$ cat charts/ix-chart/<chart version>/app-readme.md

# iX-Chart

iX-chart is a chart designed to let user deploy a docker image in a TrueNAS SCALE kubernetes cluster.
It provides a mechanism to specify workload type, add external host interfaces in the pods, configure volumes and allocate host resources to the workload.

Then add a questions.yaml file to prompt the user for something.

groups:
  - name: "Container Images"
    description: "Image to be used for container"
questions:
  - variable: image
    label: "Docker Image"
    description: "Docker Image Details"
    group: "Container Images"
    schema:
      type: dict
      required: true
      attrs:
        - variable: repository
          description: "Docker image repository"
          label: "Image repository"
          schema:
            type: string
            required: true
        - variable: tag
          description: "Tag to use for specified image"
          label: "Image Tag"
          schema:
            type: string
            default: "latest"
        - variable: pullPolicy
          description: "Docker Image Pull Policy"
          label: "Image Pull Policy"
          schema:
            type: string
            default: "IfNotPresent"
            enum:
              - value: "IfNotPresent"
                description: "Only pull image if not present on host"
              - value: "Always"
                description: "Always pull image even if present on host"
              - value: "Never"
                description: "Never pull image even if it's not present on host"

The above will prompt the user with 2 text fields and a dropdown in the UI getting details for image configuration in a helm chart.

Question Variable Reference

Variable	Type	Required	Description
variable	string	true	define the variable name specified in the values.yamlfile.
label	string	true	define the UI label.
description	string	false	specify the description of the variable.
group	string	false	group questions by input value.
schema	dictionary	true	specify schema details for the variable
schema.type	string	true	specify type of value for variable (current supported types are string, int, boolean, path, hostpath, list, dict, ipaddr, and cron).
schema.required	bool	false	define if the variable is required or not (true \ false), defaults to false
schema.default	object	false	specify the default value.
schema.min_length	int	false	min character length for string type variable.
schema.max_length	int	false	max character length for string type variable.
schema.min	int	false	min integer length.
schema.max	int	false	max integer length.
schema.enum	[]dictionary	false	specify the options when the variable type is string, for example, enum: - value: "RollingUpdate"   description: "Create new pods and then kill old ones" - value: "Recreate"   description: "Kill existing pods before creating new ones"
schema.valid_chars	string	false	regular expression for input chars validation.
schema.subquestions	[]subquestion	false	add an array of subquestions.
schema.show_if	string	false	show current variable if condition specified is true, for example show_if: [["workloadType", "=", "CronJob"]]
schema.show_subquestions_if	string	false	show subquestions if is true or equal to one of the options. for example show_subquestion_if: "static". system will convert this to the filters format specifid for shcema.show_if automatically.
schema.attrs	[]variables	false	specified when schema.type is dictionary to declare attributes allowed in the dictionary.
schema.items	[]variables	false	specified when schema.type is list to declare attributes allowed in the list.
schema.private	bool	false	specified for declaring information sensitive fields.
schema.null	bool	false	specifies if the value for the variable can be null. defaults to false.

subquestions: subquestions[] cannot contain subquestions or show_subquestions_if keys, but all other keys in the above table are supported. Also variables having schema.type list do not support subquestions.

There are some novel cases where we would like to provide ability to configure / manage resources for workloads with getting some data from system dynamically. So a chart can specify certain actions to be performed by the system for a variable by defining a reference. An example better illustrates this concept:

- variable: volume
  label: "Volume"
  schema:
    type: dict
    $ref:
      - "normalize/ixVolume"
    attrs:
      - variable: mountPath
        label: "Mount Path"
        description: "Path where the volume will be mounted inside the pod"
        schema:
          type: path
          required: true
      - variable: datasetName
        label: "Dataset Name"
        schema:
          type: string
          required: true

In the above variable we define a $ref in schema which specifies that the system should take some action for normalising the value specified for the variable. In this specific case, ix_volume is a concept introduced where we recommend using a volume which we are able to rollback automatically on chart release rollback. In essence, it is just a hostPath volume for which the system automatically creates the dataset specified.

We have following types of actions supported in $ref right now:

1. definitions
2. normalize

For (1), system will automatically update schema for a particular definition. For example,

- variable: hostInterface
  description: "Please specify host interface"
  label: "Host Interface"
  schema:
    type: string
    required: true
    $ref:
      - "definitions/interface"

System will automatically populate available interfaces for the user based on what interfaces are available on the system.

For (2), system will normalize values or perform some actions as discussed above.