Allow fetching version from a remote URL

Signed-off-by: Knut Ahlers <knut@ahlers.me>

executor.go

@@ -53,17 +53,22 @@ func executePackage(pkg pkgCfg, pkgLog *log.Entry) error {
 		return err
 	}
 
-	if !str.StringInSlice(pkg.Version, []string{"", "master"}) {
+	ver, err := pkg.Version()
+	if err != nil {
+		return err
+	}
+
+	if !str.StringInSlice(ver, []string{"", "master"}) {
 		pkgLog.Debug("Resetting to specified version")
 		pkgPath := path.Join(os.Getenv("GOPATH"), "src", pkg.Name)
 
 		// Fetch required references
-		if err := executeCommand([]string{"git", "fetch", "-q", "--tags", "origin", pkg.Version}, stdout, stderr, pkgPath); err != nil {
+		if err := executeCommand([]string{"git", "fetch", "-q", "--tags", "origin", ver}, stdout, stderr, pkgPath); err != nil {
 			return err
 		}
 
 		// Do the real reset
-		if err := executeCommand([]string{"git", "reset", "--hard", pkg.Version}, stdout, stderr, pkgPath); err != nil {
+		if err := executeCommand([]string{"git", "reset", "--hard", ver}, stdout, stderr, pkgPath); err != nil {
 			return err
 		}
 	}

main.go

@@ -13,20 +13,6 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-type pkgCfg struct {
-	Name    string `yaml:"name"`
-	Single  bool   `yaml:"single"`
-	Version string `yaml:"version"`
-}
-
-type configFile struct {
-	Cwd          string     `yaml:"cwd"`
-	GoPath       string     `yaml:"gopath"`
-	Packages     []pkgCfg   `yaml:"packages"`
-	PreCommands  [][]string `yaml:"pre_commands"`
-	PostCommands [][]string `yaml:"post_commands"`
-}
-
 var (
 	cfg = struct {
 		Config         string `flag:"config,c" default:"~/.config/gotools.yml" description:"Configuration for update-gotools utility"`
@@ -109,7 +95,13 @@ func runPackageBuilds(n int, filter func(pkgCfg) bool) {
 
 		limit.Add()
 		go func(pkg pkgCfg) {
-			logVer := pkg.Version
+			logVer, err := pkg.Version()
+			if err != nil {
+				log.WithFields(log.Fields{
+					"pkg": pkg.Name,
+				}).WithError(err).Fatal("Unable to fetch version information")
+			}
+
 			if logVer == "" {
 				logVer = "HEAD"
 			}

types.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"io/ioutil"
+	"net/http"
+)
+
+type pkgCfg struct {
+	Name       string `yaml:"name"`
+	Single     bool   `yaml:"single"`
+	Ver        string `yaml:"version"`
+	VersionURL string `yaml:"version_url"`
+}
+
+type configFile struct {
+	Cwd          string     `yaml:"cwd"`
+	GoPath       string     `yaml:"gopath"`
+	Packages     []pkgCfg   `yaml:"packages"`
+	PreCommands  [][]string `yaml:"pre_commands"`
+	PostCommands [][]string `yaml:"post_commands"`
+}
+
+func (p *pkgCfg) Version() (string, error) {
+	if p.Ver != "" {
+		return p.Ver, nil
+	}
+
+	if p.VersionURL != "" {
+		resp, err := http.Get(p.VersionURL)
+		if err != nil {
+			return "", err
+		}
+		defer resp.Body.Close()
+
+		v, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return "", err
+		}
+
+		p.Ver = string(v)
+		return p.Ver, nil
+	}
+
+	return "", nil
+}