Make functionbeat build process depends on linux/amd64

CHANGELOG-developer.asciidoc

@@ -62,3 +62,4 @@ The list below covers the major changes between 6.3.0 and master only.
 - Add `mage.GenerateFieldsGo` for generating fields.go files. {pull}8615[8615]
 - Add `mage.KibanaDashboards` for collecting Kibana dashboards and generating index patterns. {pull}8615[8615]
 - Allow to disable config resolver using the `Settings.DisableConfigResolver` field when initializing libbeat. {pull}8769[8769]
+- Add `mage.AddPlatforms` to allow to specify dependent platforms when building a beat. {pull}8889[8889]

dev-tools/mage/crossbuild.go

@@ -88,6 +88,17 @@ func ImageSelector(f ImageSelectorFunc) func(params *crossBuildParams) {
 	}
 }
 
+// AddPlatforms sets dependencies on others platforms.
+func AddPlatforms(expressions ...string) func(params *crossBuildParams) {
+	return func(params *crossBuildParams) {
+		var list BuildPlatformList
+		for _, expr := range expressions {
+			list = NewPlatformList(expr)
+			params.Platforms = params.Platforms.Merge(list)
+		}
+	}
+}
+
 type crossBuildParams struct {
 	Platforms     BuildPlatformList
 	Target        string

dev-tools/mage/platforms.go

@@ -445,6 +445,14 @@ func (list BuildPlatformList) Filter(expr string) BuildPlatformList {
 	return out.deduplicate()
 }
 
+// Merge creates a new list with the two list merged.
+func (list BuildPlatformList) Merge(with BuildPlatformList) BuildPlatformList {
+	out := make(BuildPlatformList, 0, len(list)+len(with))
+	out = append(list, with...)
+	out = append(out, with...)
+	return out.deduplicate()
+}
+
 // deduplicate removes duplicate platforms and sorts the list.
 func (list BuildPlatformList) deduplicate() BuildPlatformList {
 	set := map[string]BuildPlatform{}

x-pack/functionbeat/magefile.go

@@ -39,7 +39,7 @@ func BuildGoDaemon() error {
 
 // CrossBuild cross-builds the beat for all target platforms.
 func CrossBuild() error {
-	return mage.CrossBuild()
+	return mage.CrossBuild(mage.AddPlatforms("linux/amd64"))
 }
 
 // CrossBuildGoDaemon cross-builds the go-daemon binary using Docker.