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mkctr: add support for volumes #27

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bradfitz merged 1 commit into from
Jan 5, 2026
Merged

mkctr: add support for volumes #27

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13 changes: 12 additions & 1 deletion mkctr.go
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ type buildParams struct {
target string
verbose bool
annotations map[string]string // OCI image annotations
volumes map[string]struct{}
}

func main() {
Expand All @@ -94,6 +95,7 @@ func main() {
gopaths = flag.String("gopaths", "", "comma-separated list of go paths in src:dst form")
files = flag.String("files", "", "comma-separated list of static files in src:dst form")
repos = flag.String("repos", "", "comma-separated list of image registries")
volumes = flag.String("volumes", "", "comma-separated list of volumes to add")
tagArg = flag.String("tags", "", "comma-separated tags")
ldflagsArg = flag.String("ldflags", "", "the --ldflags value to pass to go")
gotags = flag.String("gotags", "", "the --tags value to pass to go")
Expand Down Expand Up @@ -136,6 +138,13 @@ func main() {
if len(paths) == 0 && len(staticFiles) == 0 {
log.Fatal("at least one of --files or --gopaths must be set")
}
var vols map[string]struct{}
for vol := range strings.SplitSeq(*volumes, ",") {
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@bradfitz bradfitz Jan 5, 2026

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this requires Go 1.24. But the go.mod still says 1.23.

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@bradfitz bradfitz Jan 5, 2026

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Fixed go.mod in #31

if vols == nil {
vols = make(map[string]struct{})
}
vols[strings.TrimSpace(vol)] = struct{}{}
Comment on lines +143 to +146
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Copilot AI Jan 5, 2026

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The volume parsing logic doesn't handle empty strings correctly. When the volumes flag is empty (default value ""), strings.SplitSeq will still yield one iteration with an empty string, which will be added to the map after TrimSpace. This results in an empty volume key being added to the volumes map.

Consider adding a check to skip empty strings after trimming, or check if the volumes string is empty before attempting to parse it.

Suggested change
if vols == nil {
vols = make(map[string]struct{})
}
vols[strings.TrimSpace(vol)] = struct{}{}
vol = strings.TrimSpace(vol)
if vol == "" {
continue
}
if vols == nil {
vols = make(map[string]struct{})
}
vols[vol] = struct{}{}

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}

bp := &buildParams{
baseImage: *baseImage,
Expand All @@ -149,6 +158,7 @@ func main() {
verbose: *verbose,
goarch: strings.Split(*goarch, ","),
annotations: parseAnnotations(*annotations),
volumes: vols,
}

if err := fetchAndBuild(bp); err != nil {
Expand Down Expand Up @@ -306,7 +316,8 @@ func fetchAndBuild(bp *buildParams) error {

if args := flag.Args(); len(args) > 0 {
img, err = mutate.Config(img, v1.Config{
Cmd: args,
Cmd: args,
Volumes: bp.volumes,
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@bradfitz bradfitz Jan 5, 2026

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This part shouldn't be conditional on len(args) > 0 (setting an entrypoint)

I noted this in my upcoming PR to add env var support too.

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@bradfitz bradfitz Jan 5, 2026

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I'll handle this fix in my upcoming PR.

})
if err != nil {
return err
Expand Down