Merge pull request #694 from ijc/apply-config-to-state

client/llb: factor out `State.WithConfig` from `Image`.

client/llb/source.go

@@ -126,30 +126,11 @@ func Image(ref string, opts ...ImageOption) State {
 		if err != nil {
 			src.err = err
 		} else {
-			var img struct {
-				Config struct {
-					Env        []string `json:"Env,omitempty"`
-					WorkingDir string   `json:"WorkingDir,omitempty"`
-					User       string   `json:"User,omitempty"`
-				} `json:"config,omitempty"`
-			}
-			if err := json.Unmarshal(dt, &img); err != nil {
-				src.err = err
-			} else {
-				st := NewState(src.Output())
-				for _, env := range img.Config.Env {
-					parts := strings.SplitN(env, "=", 2)
-					if len(parts[0]) > 0 {
-						var v string
-						if len(parts) > 1 {
-							v = parts[1]
-						}
-						st = st.AddEnv(parts[0], v)
-					}
-				}
-				st = st.Dir(img.Config.WorkingDir)
+			st, err := NewState(src.Output()).WithImageConfig(dt)
+			if err == nil {
 				return st
 			}
+			src.err = err
 		}
 	}
 	return NewState(src.Output())

client/llb/state.go

@@ -2,8 +2,10 @@ package llb
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"net"
+	"strings"
 
 	"github.com/containerd/containerd/platforms"
 	"github.com/moby/buildkit/identity"
@@ -171,6 +173,31 @@ func (s State) WithOutput(o Output) State {
 	return s
 }
 
+func (s State) WithImageConfig(c []byte) (State, error) {
+	var img struct {
+		Config struct {
+			Env        []string `json:"Env,omitempty"`
+			WorkingDir string   `json:"WorkingDir,omitempty"`
+			User       string   `json:"User,omitempty"`
+		} `json:"config,omitempty"`
+	}
+	if err := json.Unmarshal(c, &img); err != nil {
+		return State{}, err
+	}
+	for _, env := range img.Config.Env {
+		parts := strings.SplitN(env, "=", 2)
+		if len(parts[0]) > 0 {
+			var v string
+			if len(parts) > 1 {
+				v = parts[1]
+			}
+			s = s.AddEnv(parts[0], v)
+		}
+	}
+	s = s.Dir(img.Config.WorkingDir)
+	return s, nil
+}
+
 func (s State) Run(ro ...RunOption) ExecState {
 	ei := &ExecInfo{State: s}
 	if p := s.GetPlatform(); p != nil {