Merge pull request #4055 from deitch/include-semver-in-version

properly save linuxkit version

src/cmd/linuxkit/Makefile

@@ -1,5 +1,24 @@
-VERSION?="v0.0-dev"
+# determine the version we save in the build binary
+# we always include the git commit.
+# the version is the current semver if it this commit matches the tag,
+# else it is the following: <tag>-<commits since tag>-<short commit hash>
+# if the git tree is dirty, append "-dirty"
+# most recent commit
 GIT_COMMIT=$(shell git rev-list -1 HEAD)
+# whether or not it is dirty, i.e. has uncommitted changes
+GIT_DIRTY=$(shell git update-index -q --refresh && git diff-index --quiet HEAD -- . || echo "-dirty")
+# most recent tag, might or might not point to GIT_COMMIT
+GIT_TAG=$(shell git describe --tags --match="v*")
+# include the possible "-dirty" suffix
+VERSION=$(GIT_TAG)$(GIT_DIRTY)
+
+report:
+	@echo "VERSION: $(VERSION)"
+	@echo "GIT_COMMIT: $(GIT_COMMIT)"
+	@echo "GIT_DIRTY: $(GIT_DIRTY)"
+	@echo "GIT_TAG: $(GIT_TAG)"
+	@echo "VERSION: $(VERSION)"
+
 GO_COMPILE?=linuxkit/go-compile:c97703655e8510b7257ffc57f25e40337b0f0813
 export GO_FLAGS=-mod=vendor
 

src/cmd/linuxkit/version.go

@@ -10,11 +10,22 @@ import (
 )
 
 func versionCmd() *cobra.Command {
+	var short, commit bool
 	cmd := &cobra.Command{
 		Use:   "version",
 		Short: "report the version of linuxkit",
-		Long:  `Report the version of linuxkit.`,
+		Long: `Report the version of linuxkit.
+		Run with option --short to print just the version number.
+		Run with option --commit to print just the git commit.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			if short {
+				fmt.Println(version.Version)
+				return nil
+			}
+			if commit {
+				fmt.Println(version.GitCommit)
+				return nil
+			}
 			fmt.Printf("%s version %s\n", filepath.Base(os.Args[0]), version.Version)
 			if version.GitCommit != "" {
 				fmt.Printf("commit: %s\n", version.GitCommit)
@@ -22,6 +33,8 @@ func versionCmd() *cobra.Command {
 			return nil
 		},
 	}
+	cmd.Flags().BoolVar(&short, "short", false, "print just the version number")
+	cmd.Flags().BoolVar(&commit, "commit", false, "print just the commit")
 
 	return cmd
 }