Implement check and add headers in mage (elastic#13215)

Add a framework to wrap go tooling in mage, taken from go-txtfile.

Using it, reimplement all uses of go-licenser in mage.

go-licenser is vendored.

Makefile

@@ -98,16 +98,12 @@ check: python-env
 	@git diff-index --exit-code HEAD --
 
 .PHONY: check-headers
-check-headers:
-	@go get -u github.com/elastic/go-licenser
-	@go-licenser -d -exclude x-pack -exclude generator/beat/\{beat\} -exclude generator/metricbeat/\{beat\}
-	@go-licenser -d -license Elastic x-pack
+check-headers: mage
+	@mage checkLicenseHeaders
 
 .PHONY: add-headers
-add-headers:
-	@go get github.com/elastic/go-licenser
-	@go-licenser -exclude x-pack
-	@go-licenser -license Elastic x-pack
+add-headers: mage
+	@mage addLicenseHeaders
 
 # Corrects spelling errors
 .PHONY: misspell

NOTICE.txt

@@ -859,6 +859,22 @@ License type (autodetected): Apache-2.0
 Apache License 2.0
 
 
+--------------------------------------------------------------------
+Dependency: github.com/elastic/go-licenser
+Version: 0.2.0
+Revision: 2b2abd4ee9b58025ebd0630d7621cfd7619f58ac
+License type (autodetected): Apache-2.0
+./vendor/github.com/elastic/go-licenser/LICENSE:
+--------------------------------------------------------------------
+Apache License 2.0
+
+-------NOTICE-----
+Elastic go-licenser
+Copyright 2018 Elasticsearch B.V.
+
+This product includes software developed at
+Elasticsearch, B.V. (https://www.elastic.co/).
+
 --------------------------------------------------------------------
 Dependency: github.com/elastic/go-lookslike
 Version: =v0.3.0

dev-tools/mage/check.go

@@ -35,6 +35,7 @@ import (
 	"github.com/magefile/mage/sh"
 	"github.com/pkg/errors"
 
+	"github.com/elastic/beats/dev-tools/mage/gotool"
 	"github.com/elastic/beats/libbeat/processors/dissect"
 )
 
@@ -189,6 +190,26 @@ func GoVet() error {
 	return errors.Wrap(err, "failed running go vet, please fix the issues reported")
 }
 
+// CheckLicenseHeaders checks license headers in .go files.
+func CheckLicenseHeaders() error {
+	fmt.Println(">> fmt - go-licenser: Checking for missing headers")
+
+	mg.Deps(InstallGoLicenser)
+
+	var license string
+	switch BeatLicense {
+	case "ASL2", "ASL 2.0":
+		license = "ASL2"
+	case "Elastic", "Elastic License":
+		license = "Elastic"
+	default:
+		return errors.Errorf("unknown license type %v", BeatLicense)
+	}
+
+	licenser := gotool.Licenser
+	return licenser(licenser.Check(), licenser.License(license))
+}
+
 // CheckDashboardsFormat checks the format of dashboards
 func CheckDashboardsFormat() error {
 	dashboardSubDir := "/_meta/kibana/"

dev-tools/mage/fmt.go

@@ -26,6 +26,8 @@ import (
 	"github.com/magefile/mage/mg"
 	"github.com/magefile/mage/sh"
 	"github.com/pkg/errors"
+
+	"github.com/elastic/beats/dev-tools/mage/gotool"
 )
 
 var (
@@ -35,9 +37,6 @@ var (
 	// GoImportsLocalPrefix is a string prefix matching imports that should be
 	// grouped after third-party packages.
 	GoImportsLocalPrefix = "github.com/elastic"
-
-	// GoLicenserImportPath controls the import path used to install go-licenser.
-	GoLicenserImportPath = "github.com/elastic/go-licenser"
 )
 
 // Format adds license headers, formats .go files with goimports, and formats
@@ -120,9 +119,7 @@ func AddLicenseHeaders() error {
 
 	fmt.Println(">> fmt - go-licenser: Adding missing headers")
 
-	if err := sh.Run("go", "get", GoLicenserImportPath); err != nil {
-		return err
-	}
+	mg.Deps(InstallGoLicenser)
 
 	var license string
 	switch BeatLicense {
@@ -134,5 +131,6 @@ func AddLicenseHeaders() error {
 		return errors.Errorf("unknown license type %v", BeatLicense)
 	}
 
-	return sh.RunV("go-licenser", "-license", license)
+	licenser := gotool.Licenser
+	return licenser(licenser.License(license))
 }

dev-tools/mage/gotool/get.go

@@ -0,0 +1,31 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package gotool
+
+type goGet func(opts ...ArgOpt) error
+
+// Get runs `go get` and provides optionals for adding command line arguments.
+var Get goGet = runGoGet
+
+func runGoGet(opts ...ArgOpt) error {
+	args := buildArgs(opts)
+	return runVGo("get", args)
+}
+
+func (goGet) Update() ArgOpt            { return flagBoolIf("-u", true) }
+func (goGet) Package(pkg string) ArgOpt { return posArg(pkg) }