Alter schema of 'index.yaml'

[technosophos]

The current index.yaml file looks like this:

mariner-4.3.2:
  name: mariner-4.3.2
  url: localhost:8879/charts/mariner-4.3.2.tgz
  chartfile:
    name: mariner
    version: "4.3.2"
    description: Some description
    icon: https://example.com/path/to/icon.png
mariner-4.1.1:
  name: mariner-4.1.1
  url: localhost:8879/charts/mariner-4.1.1.tgz
  chartfile:
    name: mariner
    version: "4.3.2"
    description: Some description
    icon: https://example.com/path/to/icon.png
alpine-0.1.0:
  name: alpine-0.1.0
  url: localhost:8879/charts/alpine-0.1.0.tgz
  chartfile: ...

There have been ongoing discussions to alter this format before Alpha.5 releases. The goals for altering are:

• Fewer repeated fields
• Flatter chart metadata
• Easier structure for clients to process, where clients may be helm or something much simpler like jq.

Here's the proposed new version:

mariner:
  - version: "4.3.2"
     url: localhost:8879/charts/mariner-4.3.2.tgz
     digest: "sha256:..."
     name: mariner
     description: Some description
     icon: https://example.com/path/to/icon.png
     # rest of Chart.yaml fields
  - version: "4.1.1"
    url: localhost:8879/charts/mariner-4.1.1.tgz
    digest: "sha256:..."
    name: mariner
    description: Some description
    icon: https://example.com/path/to/icon.png
    # rest of Chart.yaml fields
alpine:
  - version: 0.1.0
     url: localhost:8879/charts/alpine-0.1.0.tgz
     # ...

This presents the data in a more tree-like way:

CHART:
    VERSIONS[]
CHART:
    VERSIONS[]

Note that it does collapse the chartfile fields into the versions object.

When it comes to ordering the VERSIONS[] list, it should be ordered by version, descending. So the newest release is in VERSIONS[0]. Assessing the stability of a version is done by SemVer 2 rules.

[technosophos]

/cc @prydonius @migmartri @viglesiasce @adamreese @jackfrancis @michelleN

[technosophos]

Related to #1197 and #1153

[philips]

Overall it LGTM.

I would consider adding a "URLs" field like OCI has in case of mirrors.

Also, I would like to see a recognized DNS federated namespace for helm packages but that can be a separate issue. It would affect this design potentially though.

[technosophos]

Adding a URLs field where?

[jackfrancis]

@philips could you elaborate on the DNS federated namespace idea? What's an example use-case?

[jstrachan]

@technosophos I was assuming this was instead of url to support having repository mirrors

@philips good idea. Though right now we ignore the URL field in the index.yaml anyways :) #1169

[technosophos]

Okay, changing to support urls: {} instead of a single URL.