fix: Force PLATFORMS environment variable when we build Elastic Agent…

… dependencies on arm64 (#26415)

* fix: build elastic agent dependencies on the architecture you are running

* fix: format

* fix: build ARM on ARM

* fix: format

* chore: backup the platforms env var

x-pack/elastic-agent/magefile.go

@@ -579,6 +579,16 @@ func packageAgent(requiredPackages []string, packagingFn func()) {
  }
 
  os.Setenv(agentDropPath, dropPath)
+ if runtime.GOARCH == "arm64" {
+ const platformsVar = "PLATFORMS"
+ oldPlatforms := os.Getenv(platformsVar)
+ os.Setenv(platformsVar, runtime.GOOS+"/"+runtime.GOARCH)
+ if oldPlatforms != "" {
+ defer os.Setenv(platformsVar, oldPlatforms)
+ } else {
+ defer os.Unsetenv(oldPlatforms)
+ }
+ }
 
  // cleanup after build
  defer os.RemoveAll(dropPath)