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[build]: add buildkit ssh forwarding support #76

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Merged
JaewonHur merged 1 commit into from
May 27, 2026
+50 −1
Merged

[build]: add buildkit ssh forwarding support #76

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16 changes: 15 additions & 1 deletion pkg/build/build.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ import (
"github.com/moby/buildkit/cmd/buildctl/build"
"github.com/moby/buildkit/session"
"github.com/moby/buildkit/session/secrets/secretsprovider"
"github.com/moby/buildkit/session/sshforward/sshprovider"
"github.com/sirupsen/logrus"
"github.com/tonistiigi/go-csvvalue"
"google.golang.org/grpc"
Expand Down Expand Up @@ -64,7 +65,8 @@ func Build(ctx context.Context, opts *BOpts) error {

if len(exports) == 0 {
exports = append(exports, client.ExportEntry{
Type: "oci",
Type: "oci",
Attrs: map[string]string{},
})
}

Expand All @@ -89,6 +91,10 @@ func Build(ctx context.Context, opts *BOpts) error {

var exportsWithOutput []client.ExportEntry
for _, export := range exports {
if export.Attrs == nil {
export.Attrs = map[string]string{}
}

switch export.Type {
case client.ExporterLocal:
localDest := filepath.Join(GlobalExportPath, opts.BuildID, "local")
Expand Down Expand Up @@ -167,6 +173,14 @@ func Build(ctx context.Context, opts *BOpts) error {
}
solveOpt.Frontend = "dockerfile.v1"

if len(opts.SSH) > 0 {
sshProvider, err := sshprovider.NewSSHAgentProvider(opts.SSH)
if err != nil {
return err
}
solveOpt.Session = append(solveOpt.Session, sshProvider)
}

_, err = buildkit.Build(opts.Context(ctx), solveOpt, "", frontend, opts.ProgressWriter.Status())
<-opts.ProgressWriter.Done()
return err
Expand Down
35 changes: 35 additions & 0 deletions pkg/build/buildopts.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ import (
"github.com/moby/buildkit/frontend/dockerfile/instructions"
"github.com/moby/buildkit/frontend/dockerfile/parser"
"github.com/moby/buildkit/frontend/dockerfile/shell"
"github.com/moby/buildkit/session/sshforward/sshprovider"
"github.com/moby/buildkit/util/progress/progresswriter"
ocispecs "github.com/opencontainers/image-spec/specs-go/v1"

Expand Down Expand Up @@ -62,6 +63,8 @@ const (
KeyBuildArgs = "build-args"
// RUN --mount=type=secret,... id:value pairs passed to the Dockerfile.
KeySecrets = "secrets"
// SSH agent to forward during the build process.
KeySSH = "ssh"
// Cache import sources.
KeyCacheIn = "cache-in"
// Cache export destinations.
Expand Down Expand Up @@ -94,6 +97,7 @@ type BOpts struct {
Target string
BuildArgs map[string]string
Secrets map[string][]byte
SSH []sshprovider.AgentConfig
CacheIn []string
CacheOut []string
Outputs []string
Expand Down Expand Up @@ -237,12 +241,42 @@ func NewBuildOpts(ctx context.Context, basePath string, contextMap map[string][]
return args, nil
}

sshExtract := func(key string) []sshprovider.AgentConfig {
values, ok := contextMap[key]
if !ok {
return nil
}
agentConfigs := make([]sshprovider.AgentConfig, 0, len(values))
for _, value := range values {
id, path, hasPath := strings.Cut(value, "=")
id = strings.TrimSpace(id)
path = strings.TrimSpace(path)
if !hasPath && strings.HasPrefix(id, "/") {
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@JaewonHur JaewonHur May 20, 2026

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What is this for? Does docker support docker build --ssh /path/to/sock?

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@saehejkang saehejkang May 21, 2026

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It handles any case in which there is no = and it starts with /. This would be converted to id=default, path=/path/to/sock (interpreted as a socket path). I believe docker does support this, but I found online that using the explicit form of default=/path/to/sock is more clear for use cases.

path = id
id = "default"
hasPath = true
}
if id == "" {
id = "default"
}
config := sshprovider.AgentConfig{
ID: id,
}
if hasPath && path != "" {
config.Paths = []string{path}
}
agentConfigs = append(agentConfigs, config)
}
return agentConfigs
}

labels := mapExtract(KeyLabels)
buildArgs := mapExtract(KeyBuildArgs)
secrets, err := mapExtractB64(KeySecrets)
if err != nil {
return nil, err
}
ssh := sshExtract(KeySSH)
cacheIn := contextMap[KeyCacheIn]
cacheOut := contextMap[KeyCacheOut]
outputs := contextMap[KeyOutput]
Expand Down Expand Up @@ -342,6 +376,7 @@ func NewBuildOpts(ctx context.Context, basePath string, contextMap map[string][]
Labels: labels,
BuildArgs: buildArgs,
Secrets: secrets,
SSH: ssh,
CacheIn: cacheIn,
CacheOut: cacheOut,
Outputs: outputs,
Expand Down
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