feat(update): #23 add fossa update command

build/sbt.go

@@ -1,7 +1,6 @@
 package build
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -144,10 +143,10 @@ func (builder *SBTBuilder) IsBuilt(m module.Module, allowUnresolved bool) (bool,
 
 // IsModule is not implemented
 func (builder *SBTBuilder) IsModule(target string) (bool, error) {
-	return false, errors.New("IsModule is not implemented for SBTBuilder")
+	return false, fmt.Errorf("IsModule is not implemented for SBTBuilder")
 }
 
 // InferModule is not implemented
 func (builder *SBTBuilder) InferModule(target string) (module.Module, error) {
-	return module.Module{}, errors.New("InferModule is not implemented for SBTBuilder")
+	return module.Module{}, fmt.Errorf("InferModule is not implemented for SBTBuilder")
 }

cmd/fossa/main.go

@@ -110,6 +110,12 @@ func main() {
 				cli.BoolFlag{Name: "debug", Usage: debugUsage},
 			},
 		},
+		{
+			Name:   "update",
+			Usage:  "Updates `fossa` to the latest version",
+			Action: updateCmd,
+			Flags:  []cli.Flag{},
+		},
 	}
 
 	app.Run(os.Args)
@@ -244,6 +250,10 @@ func defaultCmd(c *cli.Context) {
 		mainLogger.Fatalf("Could not load configuration: %s", err.Error())
 	}
 
+	if err := checkUpdate(); err != nil {
+		mainLogger.Infof("An update is available for this CLI; run `fossa update` to get the latest version.")
+	}
+
 	if len(config.modules) == 0 {
 		mainLogger.Fatal("No modules specified for analysis.")
 	}

cmd/fossa/update.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+	"github.com/blang/semver"
+	logging "github.com/op/go-logging"
+	"github.com/rhysd/go-github-selfupdate/selfupdate"
+	"github.com/urfave/cli"
+)
+
+var updateLogger = logging.MustGetLogger("update")
+var updateEndpoint := "fossas/fossa-cli"
+
+func checkUpdate() error {
+	latest, found, err := selfupdate.DetectLatest(updateEndpoint)
+	if err != nil {
+		return err // unable to update due to GH error
+	}
+
+	v := semver.MustParse(version)
+	if !found || latest.Version.Equals(v) {
+		return fmt.Errorf("current binary is latest version") 
+	}
+}
+
+func doSelfUpdate() error {
+	v := semver.MustParse(version)
+	latest, err := selfupdate.UpdateSelf(v, updateEndpoint)
+	if err != nil { 
+		return err
+	}
+	if latest.Version.Equals(v) {
+		// latest version is the same as current version. It means current binary is up to date.
+		return fmt.Errorf("no update required; currently on latest")
+	}
+	return nil
+}
+
+func updateCmd(c *cli.Context) {
+	if err := checkUpdate(); err != nil {
+		updateLogger.Fatalf("unable to update (%s)", err)
+	}
+
+	if err := doSelfUpdate(); err != nil {
+		updateLogger.Fatalf("unable failed (%s)", err)
+	}
+
+	updateLogger.Info("fossa has been updated; run `fossa -v` to view the current version")
+}