Fix arg handling for multi-stage images in COPY instructions. (#621)

integration/dockerfiles/Dockerfile_test_arg_multi

@@ -0,0 +1,12 @@
+ARG FILE_NAME=myFile
+
+FROM busybox:latest AS builder
+ARG FILE_NAME
+
+RUN echo $FILE_NAME && touch /$FILE_NAME.txt && stat /$FILE_NAME.txt;
+
+FROM busybox:latest
+ARG FILE_NAME
+
+RUN echo $FILE_NAME && touch /$FILE_NAME.txt && stat /$FILE_NAME.txt;
+COPY --from=builder /$FILE_NAME.txt /

pkg/commands/arg.go

@@ -30,27 +30,35 @@ type ArgCommand struct {
 
 // ExecuteCommand only needs to add this ARG key/value as seen
 func (r *ArgCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.BuildArgs) error {
-	replacementEnvs := buildArgs.ReplacementEnvs(config.Env)
-	resolvedKey, err := util.ResolveEnvironmentReplacement(r.cmd.Key, replacementEnvs, false)
+	key, val, err := ParseArg(r.cmd.Key, r.cmd.Value, config.Env, buildArgs)
 	if err != nil {
 		return err
 	}
+
+	buildArgs.AddArg(key, val)
+	return nil
+}
+
+func ParseArg(key string, val *string, env []string, ba *dockerfile.BuildArgs) (string, *string, error) {
+	replacementEnvs := ba.ReplacementEnvs(env)
+	resolvedKey, err := util.ResolveEnvironmentReplacement(key, replacementEnvs, false)
+	if err != nil {
+		return "", nil, err
+	}
 	var resolvedValue *string
-	if r.cmd.Value != nil {
-		value, err := util.ResolveEnvironmentReplacement(*r.cmd.Value, replacementEnvs, false)
+	if val != nil {
+		value, err := util.ResolveEnvironmentReplacement(*val, replacementEnvs, false)
 		if err != nil {
-			return err
+			return "", nil, err
 		}
 		resolvedValue = &value
 	} else {
-		meta := buildArgs.GetAllMeta()
+		meta := ba.GetAllMeta()
 		if value, ok := meta[resolvedKey]; ok {
 			resolvedValue = &value
 		}
 	}
-
-	buildArgs.AddArg(resolvedKey, resolvedValue)
-	return nil
+	return resolvedKey, resolvedValue, nil
 }
 
 // String returns some information about the command for the image config history

pkg/executor/build.go

@@ -383,8 +383,7 @@ func CalculateDependencies(opts *config.KanikoOptions) (map[int][]string, error)
 				return nil, err
 			}
 		}
-		initializeConfig(image)
-		cfg, err := image.ConfigFile()
+		cfg, err := initializeConfig(image)
 		if err != nil {
 			return nil, err
 		}
@@ -396,7 +395,7 @@ func CalculateDependencies(opts *config.KanikoOptions) (map[int][]string, error)
 					if err != nil {
 						continue
 					}
-					resolved, err := util.ResolveEnvironmentReplacementList(cmd.SourcesAndDest, cfg.Config.Env, true)
+					resolved, err := util.ResolveEnvironmentReplacementList(cmd.SourcesAndDest, ba.ReplacementEnvs(cfg.Config.Env), true)
 					if err != nil {
 						return nil, err
 					}
@@ -411,6 +410,12 @@ func CalculateDependencies(opts *config.KanikoOptions) (map[int][]string, error)
 				if err != nil {
 					return nil, err
 				}
+			case *instructions.ArgCommand:
+				k, v, err := commands.ParseArg(cmd.Key, cmd.Value, cfg.Config.Env, ba)
+				if err != nil {
+					return nil, err
+				}
+				ba.AddArg(k, v)
 			}
 		}
 		images = append(images, image)

pkg/executor/build_test.go

@@ -207,6 +207,23 @@ RUN bar
 			},
 			want: map[int][]string{},
 		},
+		{
+			name: "args",
+			args: args{
+				dockerfile: `
+ARG myFile=foo
+FROM debian as stage1
+RUN foo
+FROM stage1
+ARG myFile
+COPY --from=stage1 /tmp/$myFile.txt .
+RUN bar
+`,
+			},
+			want: map[int][]string{
+				0: {"/tmp/foo.txt"},
+			},
+		},
 		{
 			name: "simple deps",
 			args: args{
@@ -300,7 +317,12 @@ COPY --from=stage2 /bar /bat
 				DockerfilePath: f.Name(),
 			}
 
-			if got, _ := CalculateDependencies(opts); !reflect.DeepEqual(got, tt.want) {
+			got, err := CalculateDependencies(opts)
+			if err != nil {
+				t.Errorf("got error: %s,", err)
+			}
+
+			if !reflect.DeepEqual(got, tt.want) {
 				diff := cmp.Diff(got, tt.want)
 				t.Errorf("CalculateDependencies() = %v, want %v, diff %v", got, tt.want, diff)
 			}