Only log an error if Spack actually fails

Running this:

$ spack buildcache update-index ./aksdjhfajksdf/
==> Warning: Encountered problem listing packages at file:///nfs/hgi/ah37/aksdjhfajksdf/build_cache: [Errno 2] No such file or directory: '/nfs/hgi/ah37/aksdjhfajksdf/build_cache'
==> Error: Unable to generate package index, Failed to get list of specs from file:///nfs/hgi/ah37/aksdjhfajksdf/build_cache

exits zero! Thanks Spack!

reindex/reindex.go

@@ -26,6 +26,7 @@ package reindex
 import (
 	"log/slog"
 	"os/exec"
+	"strings"
 	"time"
 
 	"github.com/wtsi-hgi/go-softpack-builder/config"
@@ -49,14 +50,20 @@ type Scheduler struct {
 func NewScheduler(conf *config.Config, builder Builder) *Scheduler {
 	reindex := func() {
 		cmd := exec.Command("spack", "buildcache", "update-index", "--", conf.S3.BinaryCache) //nolint:gosec
-
 		out, err := cmd.CombinedOutput()
+
+		var outstr, errstr string
+
+		if out != nil {
+			outstr = string(out)
+		}
+
 		if err != nil {
-			slog.Error("could not run spack buildcache update-index", "err", err.Error())
+			errstr = err.Error()
 		}
 
-		if len(out) > 0 {
-			slog.Error("spack reindex failed", "out", string(out))
+		if err != nil || strings.Contains(outstr, "Error") {
+			slog.Error("spack reindex failed", "err", errstr, "out", outstr)
 		}
 	}
 

reindex/reindex_test.go

@@ -143,7 +143,7 @@ func TestReindex(t *testing.T) {
 				started := fb.buildCalled()
 
 				getIndex(cacheDir, started)
-				So(logWriter.String(), ShouldContainSubstring, `level=ERROR msg="could not run spack buildcache update-index"`)
+				So(logWriter.String(), ShouldContainSubstring, `level=ERROR msg="spack reindex failed"`)
 				So(logWriter.String(), ShouldContainSubstring, "executable file not found in $PATH")
 			})
 		})