(chore) Move backwards compatibility checks to weaver.

[jsuereth]

Fixes #1039 - Migrate backwards compatibility checks to weaver.

• Update github actions to use ONE policy check
• Move backwards compat check to weaver policies.

Rules we enforce:

• Attributes
  • Attributes cannot be removed
  • Attributes cannot "degrade" stability (stable->experimental)
  • Stable attributes cannot change type
• Enum members
  • Stable members cannot change stability
  • Values cannot change
  • ids cannot be removed
• Metrics
  • metrics cannot be removed
  • Stable metrics cannot become unstable
  • Stable Metric units cannot change
  • Stable Metric instruments cannot change
  • Set of required/recommended attributes must remain the same

Example errors:

Stable metrics cannot change required/recommended attributes:

Violation: Metric 'http.client.request.duration' cannot change required/recommended attributes (missing '{"http.request.method"}')
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : metric.http.client.request.duration
  - SemConv attribute: 
  - Provenance: /source

Stable metrics cannot change unit type:

Violation: Metric 'http.server.request.duration' cannot change unit (was 's', now: 'ms')
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : metric.http.server.request.duration
  - SemConv attribute: 
  - Provenance: /source

Stable metrics cannot become unstable

Violation: Metric 'http.server.request.duration' cannot change from stable
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : metric.http.server.request.duration
  - SemConv attribute: 
  - Provenance: /source

Metrics cannot be removed

Violation: Metric 'http.server.request.duration' no longer exists in semantic conventions
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : metric.http.server.request.duration
  - SemConv attribute: 
  - Provenance: /source

Violation: Attribute 'http.request.header' no longer exists in the attribute registry
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.header
  - Provenance: /source

Enums cannot lose stable members

Violation: Enum 'http.request.method' had member 'connect', but is no longer defined
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.method
  - Provenance: /source

Enum ids cannot change stable status

Violation: Enum 'http.request.method' had stable member 'get', but is no longer stable
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.method
  - Provenance: /source

Enum stable values cannot change (for same id)

Violation: Enum 'http.request.method' had stable value 'HEAD', but is now 'BAD'
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.method
  - Provenance: /source

Attributes cannot be removed form registry

Violation: Attribute 'http.request.header' no longer exists in the attribute registry
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.header
  - Provenance: /source

Stable Attributes cannot change type

Violation: Attribute 'http.request.resend_count' was 'int', but has new type 'string'
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.request.resend_count
  - Provenance: /source

Stable attributes cannot become experimental/other.

Violation: Attribute 'http.response.header' was stable, but has new stability marker
  - Category         : backward_compatibility
  - Type             : semconv_attribute
  - SemConv group    : registry.http
  - SemConv attribute: http.response.header
  - Provenance: /source

[lquerel]

I really like that we're reusing the Rego framework to test our policies, but I think that to properly/fully test them, we need integration in Weaver instead of relying solely on OPA. The reasoning is as follows:

• The names of the policy packages are meaningful for Weaver, unlike with OPA, so ideally, we need to check that too.
• The Rego extensions that we will likely introduce in Weaver over time will only be testable within Weaver.
• This isn't specific to Weaver, but in addition to the tests, we could combine both tests and Rego code coverage to aid the policy review process (code coverage is supported by Regorus).

[lquerel]

This is one of the instances where rewriting registry_attributes as shown below will accelerate the rules. Instead of having a list of attributes, we rely on a map of attribute name -> attribute.

registry_attributes := [name: attr |
    some g in data.semconv.registry_groups
    some attr in g.attributes
    name := attr.name
]