Description

Add a global ipFamily setting to the Helm chart that controls IP family
configuration for all chart-managed Kubernetes Services and adjusts container
bind addresses accordingly.

The setting accepts three values:

• ipv4 -- IPv4 SingleStack, services bind to 0.0.0.0
• ipv6 -- IPv6 SingleStack, services bind to ::
• both (default) -- PreferDualStack with IPv4 and IPv6, services bind to ::

Two new helper templates are added to _helpers.tpl:

• service_ip_family -- generates ipFamilyPolicy and ipFamilies fields
  for Service specs
• bind_address -- returns the appropriate bind address (0.0.0.0 or ::)

All four chart-managed Services now include the service_ip_family helper,
and four hardcoded [::] bind addresses in container args are replaced with
the bind_address helper.

Invalid values (including empty string) are rejected at template time with an error message.

Motivation and Context

The chart previously hardcoded [::] as the bind address and did not set
ipFamilyPolicy or ipFamilies on any Service. This made deployments on
IPv4-only fail, with no way to correctly configure the components.

Regression

No

How Has This Been Tested?

Verified with helm template for all supported values:

• Default (both): All 4 Services render with ipFamilyPolicy: PreferDualStack and ipFamilies: [IPv4, IPv6]. Bind addresses render as
  [::].
• ipv4: All 4 Services render with ipFamilyPolicy: SingleStack and
  ipFamilies: [IPv4]. Bind addresses render as [0.0.0.0].
• ipv6: All 4 Services render with ipFamilyPolicy: SingleStack and
  ipFamilies: [IPv6]. Bind addresses render as [::].
• Invalid value: helm template --set ipFamily=invalid fails with error
  invalid ipFamily value "invalid" -- valid values: ipv4, ipv6, both.
• Empty string: helm template --set ipFamily="" fails with the same
  validation error.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project (afaik :).
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added unit tests to cover my changes.