Helm OCI MediaType Registration

HIP	Title	Author(s)	Created	Type	Status
0017	Helm OCI MediaType Registration	Andrew Block andy.block@gmail.com	2022-06-09	informational	accepted

Abstract

The use of OCI artifacts is one of the packaging methods available in Helm. A Helm OCI artifact is comprised of multiple component, each defined by a specific Media Type. Media Types are managed by the Internet Assigned Numbers Authority (IANA) and each type should be registered with IANA so that it can not only be known by the organization, but also discoverable by end users. The canonical location for Helm Media Types information below is intended to be the IANA application registry. This document describes the necessary fields that are associated within the registration of a Media Type to IANA form.

Motivation

Support for the storage of Helm charts as OCI artifacts was released in released in General Availability (GA) in version 3.8.0 and with the continued adoption of this storage format, the specifications should be readily available for producers and consumers. Registration of Media Types with the Internet Assigned Numbers Authority has become a standard process within other technologies whom also make use of OCI artifacts so that not only the packaging types can be understood, but also documented.

Rationale

A Generally Available (GA) feature that implements a particular specification should account for its usage. Not only does the registration of Media Types to IANA follow a practice that has been implemented previously, but also provides a better understanding of the Helm project.

Specification

Each Media Type that Helm implements requires their own separate registration to IANA. The sections below detail the properties associated within the registration form for each of the Media Type's that will be submitted to IANA.

Helm Config

The OCI config containing a JSON formatted representation of the Helm Chart.yaml file.

Type Name	application
Tree	Vendor Tree (vnd prefix)
Subtype Name	cncf.helm.config.v1+json
Required Parameters	Fields as required per the Chart.yaml definition
Optional Parameters	Remaining fields which as defined within the Chart.yaml definition which are not noted as required
Encoding Considerations	Encoding considerations are identical to those specified for the "application/json" media type. See RFC8259.
Security Considerations	Similar security concerns common to all JSON content types. See RFC 7159 Section #12 for additional information. The included content as defined by the Helm chart definition may include sensitive assets including personal contact information, source code repositories or other referenceable locations.
Interoperability Consideration	N/A
Published specification	https://helm.sh/docs/topics/charts/#the-chartyaml-file
Application Usage	Internally within the Helm package manager as well as various interfacing applications
Fragment Identifier Considerations	N/A
Restrictions on Usage	N/A
Provisional Registrations	N/A
Additional Information	Deprecated alias names for this type: None Magic number(s): None File extension(s): .json Macintosh file type code: TEXT Object Identifiers: None
Intended Usage	Common
Other Information and Comments	N/A

Helm Content

Represents the packaged Helm chart.

Type Name	application
Tree	Vendor Tree (vnd prefix)
Subtype Name	cncf.helm.chart.content.v1.tar+gzip
Required Parameters	N/A
Optional Parameters	N/A
Encoding Considerations	Binary
Security Considerations	No security controls are enforced by Helm. The content of a Helm package is not intended to – but may potentially – contain resources that are sensitive in nature.
Interoperability Consideration	N/A
Published specification	None
Application Usage	Internally within the Helm package manager as well as various interfacing applications
Fragment Identifier Considerations	N/A
Restrictions on Usage	N/A
Provisional Registrations	N/A
Additional Information	Deprecated alias names for this type: None Magic number(s): None File extension(s): None Macintosh file type code: None Object Identifiers: None
Intended Usage	Common
Other Information and Comments	N/A

Helm Provenance

Represents the Helm Provenance file associated with a signed chart.

Type Name	application
Tree	Vendor Tree (vnd prefix)
Subtype Name	cncf.helm.chart.provenance.v1.prov
Required Parameters	Fields as specified within Helm provenance file definition
Optional Parameters N/A
Encoding Considerations	The utf-8 charset is always used for this type
Security Considerations	The contents of a Helm provenance file contains a GnuPG detached ASCII-armored signature of the Helm chart definition file as well as the definition itself. The Helm chart definition may include sensitive assets including personal contact information, source code repositories or other referenceable locations.
Interoperability Consideration	N/A
Published specification	https://helm.sh/docs/topics/provenance/#the-provenance-file
Application Usage	Internally within the Helm package manager as well as various interfacing applications
Fragment Identifier Considerations	N/A
Restrictions on Usage	N/A
Provisional Registrations	N/A
Additional Information	Deprecated alias names for this type: None Magic number(s): None File extension(s): None Macintosh file type code: Text Object Identifiers: None
Intended Usage	Common
Other Information and Comments	N/A

Backwards Compatibility

N/A

Security implications

N/A

Reference implementation

The responses associated with each Media Type registration has been inspired by the previously registered IANA Media Types.

Rejected ideas

None

Open issues

None

References

Existing Media Types of similar category and purpose can be found within the list of registered IANA Media Types. The following are examples of media types that have been registered with IANA:

• json
• gzip
• wasm