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Imagine Kubernetes Marketplace

Introduction

Feel free to fork it and submit a pull request to add any software and we'll consider including it in our marketplace (if you like, raise an issue first to discuss the proposal).

STATUS: This project is currently under active development and maintenance.

Table of contents

Using

Once an application is part of the marketplace, you can install it using the GUI on ImagineKube.com or by using the Imagine CLI with a command line:

imaginekube k8s create my-cluster --applications=Longhorn,MinIO:5GB

# or

imaginekube k8s application add -c my-cluster Longhorn

Writing

There are two minimum parts to a marketplace application - a manifest.yaml, and a square aspect ratio logo.png no smaller than 80x80, no larger than 512x512 and no bigger than 20KB. Each marketplace application is in a separate top level folder in this repository. We recommend searching for official SVG versions of the logo from the upstream supplier and importing those, rather than scaling up small resolution logos just found on the web. We'd recommend leaving a small amount of padding around the logo, in a 512x512 image, about 20px on each side.

Then there are two options for how to install the application - a single Kubernetes resources configuration file called app.yaml (which can be multiple resources separated by ---) or a script called install.sh. You can supply both items, if so the app.yaml will be applied first and then the install.sh will run.

If there are certain commands to be run before the app.yaml gets applied to the cluster then you need to create a pre_install.shscript.

The pre_install.sh and install.sh if present will be executed on the master using bash as non-privileged user that has passwordless sudo permission and has kubectl access to the cluster. We envisage that install.sh script usage should be rare and we will be strictly monitoring what is in them, and NO downloading of external resources will be acceptable here (no curl https://... | sudo sh sort of functionality)

A final optional file is the post_install.md which the user will be able to view in the web UI to see additional instructions on how to use the application. It's recommended to keep this short and succinct, if you need to manage LOTS of content, then please create a community learn guide and link to it from within the post_install.md.

To control the listing of your application in the marketplace, manifest.yaml is where the magic happens. Here's an example of a manifest.yaml:

name: Foo
version: "0.1.0"
dependencies:
  - bar
maintainer: @imaginedevops.io
description: Foo is a lightweight and reliable widget maker from Example Ltd.
url: https://example.com/foo
category: management

The name is displayed in the web interface alongside the logo.png, and is searchable when you're installing marketplace applications from the CLI. If your application name has spaces in it, the name should be the spaces/hyphens version and you can add title which is a nicer display version.

The version is a string of the version of the software being installed NOT the version of the marketplace configuration. If you want to include that, use an additional -r1 or something after the version number. The dependencies are the names (can be lower case and part of the name) of any other marketplace applications that are needed by this application. This SHOULD be quoted to avoid breaking the IMAGINE API

The maintainer field can either be an email address (e.g. [email protected]) or a Twitter username (e.g. @imaginekube) and isn't displayed on the site, but is used for us to determine who to contact if there are any problems with it. This is whoever submits the application to the marketplace (not the upstream provider), and is an implied agreement to offer help to the community with issues with it (or try to find a replacement maintainer if you are unable to do so any more).

The description is used when displaying all of the applications, and is limited to a single line of up to 160 characters (any line breaks, HTML tags, etc must be removed). We feel that the length of an SMS text message is sufficient for this. This should be a description for our users of what the software does in normal terms, not overly salesy - for example "The best NoSQL database ever, with over 10,000 stars on GitHub" will not be accepted.

The url is a link to where users can read more about it. This is shortened when displayed on Imagine.com to be just the domain name with any www. removed.

Finally the category can be one of a small list of categories for applications, these are maintained by Imagine. The current list is:

  • database
  • storage
  • monitoring
  • management
  • architecture
  • security

Any category used in this field outside of those values will be removed when we accept any changes and replaced with one of those. If you want an additional category, please propose it in a GitHub issue.

Customizing

Applications support customization through a simple mechanism. This is a user defined set of variables that are then replaced within the app.yaml or install.sh (prefixed with a $). So for example a configuration of USERNAME will have the string $USERNAME replaced in app.yaml/install.sh. As this is a simple string replacement, if you use one of the Imagine ones below, they should still be prefixed with IMAGINE:.

The applications can't ask the user for these values, so they must be either a pre-configured value (to keep the app.yaml and Imagine-specific configuration separate) or one of a range of special values that Imagine will inject:

IMAGINE:ALPHANUMERIC(num)
A random string of alphanumeric characters num long
IMAGINE:WORDS(num)
A combination of num random words, separated by - for use as a readable name
IMAGINE:CLUSTER_NAME
The name of your Kubernetes cluster
IMAGINE:REGION
The code of the region where the application is deployed
IMAGINE:CLUSTER_ID
The ID of your Kubernetes cluster (for injecting something.ID.k8s.imaginekube.com as a domain)
IMAGINE:EMAIL_ADDRESS
The email address of your Imagine account
IMAGINE:MASTER_IP
The public IP address of your Kubernetes cluster's master

Note: For IMAGINE:ALPHANUMERIC(num) and IMAGINE:WORDS(num) you can also suffix :BASE64 (e.g. IMAGINE:ALPHANUMERIC(10):BASE64) to have Imagine automatically encode the random values to Base 64 before inserting them in the templates (but the non-Base 64 version is kept to present to the user as a readable/copyable value).

These are specified in the manifest.yaml like this:

configuration:
  ACCESS_KEY:
    label: "Access key"
    value: "IMAGINE:ALPHANUMERIC(10)"

Another way of customizing applications is to provide plans which will be injected in the same way as the values above, but the UI will provide a choice for which plan to install. These are specified in the manifest.yaml like this:

plans:
  - label: "5GB"
    configuration:
      APP_SIZE_GB:
        value: 5
  - label: "10GB"
    configuration:
      APP_SIZE_GB:
        value: 10

There's no label for the configuration items in plans because they are just used internally to configure the specifics of the installation (e.g. disk size usage, number of threads, RAM limits, etc) so aren't displayed to the user, unless you give them a label (if the user really should see what these are configured to).

Testing

Testing a marketplace application during development is easy, use the Imagine CLI to launch a cluster, then simply apply the app.yaml without any other options, for example:

# Create a cluster with any prerequisites
imaginekube k8s create my-cluster --applications=longhorn --save --wait

# Then apply your app.yaml
kubectl apply -f app.yaml

Then you can test it and ensure the app.yaml is standalone and working.

Contributing

To contribute an application or a fix for an application to Imagine, please fork our marketplace repository and submit a pull request. In the pull request please confirm that you're OK for the marketplace application to be distributed by us under the MIT License.

For details on contribution requirements and responsibilities, see our Contributing document.

License

The marketplace is provided by Imagine Ltd as open source under the terms of the MIT License, however software installed as part of a marketplace app may be licensed under another licence.