provenance: Retain platform information when overwriting internal params

Signed-off-by: Paulo Gomes <[email protected]>

Author: pjbgf

buildtypes/buildkit-gha/v1/README.md

@@ -18,6 +18,7 @@ All internal parameters are REQUIRED.
 
 | Parameter | Type | Description |
 | --------- | ---- | ----------- |
+| `platform` | string | The platform used to run BuildKit. This is equivalent to `environment.platform` from `buildkit@v1`. |
 | `trigger` | string | The GitHub Action event that caused the build to be executed. |
 | `invocationUri` | string | Resource URI for the GitHub action workflow instance. |
 

internal/provenance/provenance.go

@@ -70,7 +70,13 @@ func ConvertV02ToV1(v02Prov v02.ProvenancePredicate, override *v1.ProvenancePred
 					override.BuildDefinition.ResolvedDependencies...)
 		}
 		if override.BuildDefinition.InternalParameters != nil {
-			prov.BuildDefinition.InternalParameters = override.BuildDefinition.InternalParameters
+			v := override.BuildDefinition.InternalParameters.(InternalParameters)
+			env, ok := v02Prov.Invocation.Environment.(map[string]interface{})
+			if ok && len(env) > 0 {
+				v.Platform = env["platform"].(string)
+			}
+
+			prov.BuildDefinition.InternalParameters = v
 		}
 	}