version: Add versioning for github tarballs

When building from github tarballs, getting the version from `git describe` won't work. However, we can make use of $Format$ and .gitattributes as described in [1] to automatically substitute the correct version in a go variable when `git archive` is used. In particular, the correct version number will automatically be substituted when GitHub creates release tarballs. [1] https://icinga.com/blog/2022/05/25/embedding-git-commit-information-in-go-binaries/ Signed-off-by: Christophe Fergeau <[email protected]>
crc-org · Jan 23, 2024 · 206bfd4 · 206bfd4
1 parent 90e37b1
commit 206bfd4
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Showing 2 changed files with 13 additions and 2 deletions.
diff --git a/.gitattributes b/.gitattributes
@@ -0,0 +1 @@
+/pkg/cmdline/version.go export-subst
diff --git a/pkg/cmdline/version.go b/pkg/cmdline/version.go
@@ -2,13 +2,23 @@ package cmdline
 
 import (
 	"runtime/debug"
+	"strings"
 )
 
-// set using the '-X github.com/crc-org/vfkit/pkg/cmdline.gitVersion' linker flag
-var gitVersion = "unknown"
+var (
+	// set using the '-X github.com/crc-org/vfkit/pkg/cmdline.gitVersion' linker flag
+	gitVersion = "unknown"
+
+	// set through .gitattributes when `git archive` is used
+	// see https://icinga.com/blog/2022/05/25/embedding-git-commit-information-in-go-binaries/
+	gitArchiveVersion = "$Format:%(describe)$"
+)
 
 func Version() string {
 	switch {
+	// This will be substituted when building from a GitHub tarball
+	case !strings.HasPrefix(gitArchiveVersion, "$Format:"):
+		return gitArchiveVersion
 	// This will be set when building from git using make
 	case gitVersion != "":
 		return gitVersion