bake: support setting the context to null in bake

jsternberg · jsternberg · commit 3989770e78b6 · 2025-01-13T14:03:57.000-06:00
Setting the context to null in bake will cause the dockerfile to be sent
over stdin to the build and will prevent using the default context of
"." similar to how this would be used on the command line.

When the JSON is printed from bake, it will reproduce the null so
subsequent uses can keep the value.

Signed-off-by: Jonathan A. Sternberg &lt;jonathan.sternberg@docker.com&gt;
diff --git a/bake/bake.go b/bake/bake.go
@@ -1,6 +1,7 @@
 package bake
 
 import (
+	"bytes"
 	"context"
 	"encoding"
 	"io"
@@ -638,10 +639,6 @@ func (c Config) ResolveTarget(name string, overrides map[string]map[string]Overr
 		return nil, err
 	}
 	t.Inherits = nil
-	if t.Context == nil {
-		s := "."
-		t.Context = &s
-	}
 	if t.Dockerfile == nil {
 		s := "Dockerfile"
 		t.Dockerfile = &s
@@ -702,7 +699,7 @@ type Target struct {
 
 	Annotations      []string                `json:"annotations,omitempty" hcl:"annotations,optional" cty:"annotations"`
 	Attest           buildflags.Attests      `json:"attest,omitempty" hcl:"attest,optional" cty:"attest"`
-	Context          *string                 `json:"context,omitempty" hcl:"context,optional" cty:"context"`
+	Context          **string                `json:"context" hcl:"context,optional" cty:"context"`
 	Contexts         map[string]string       `json:"contexts,omitempty" hcl:"contexts,optional" cty:"contexts"`
 	Dockerfile       *string                 `json:"dockerfile,omitempty" hcl:"dockerfile,optional" cty:"dockerfile"`
 	DockerfileInline *string                 `json:"dockerfile-inline,omitempty" hcl:"dockerfile-inline,optional" cty:"dockerfile-inline"`
@@ -761,11 +758,23 @@ func (t *Target) normalize() {
 			delete(t.Contexts, k)
 		}
 	}
+	if t.Context == nil {
+		s := t.ContextPath()
+		t.Context = &s
+	}
 	if len(t.Contexts) == 0 {
 		t.Contexts = nil
 	}
 }
 
+func (t *Target) ContextPath() *string {
+	if t.Context == nil {
+		p := "."
+		return &p
+	}
+	return (*string)(*t.Context)
+}
+
 func (t *Target) Merge(t2 *Target) {
 	if t2.Context != nil {
 		t.Context = t2.Context
@@ -866,7 +875,8 @@ func (t *Target) AddOverrides(overrides map[string]Override, ent *EntitlementCon
 		keys := strings.SplitN(key, ".", 2)
 		switch keys[0] {
 		case "context":
-			t.Context = &value
+			ptr := &value
+			t.Context = &ptr
 		case "dockerfile":
 			t.Dockerfile = &value
 		case "args":
@@ -1210,37 +1220,18 @@ func isLocalPath(p string) (string, bool) {
 }
 
 func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
-	if v := t.Context; v != nil && *v == "-" {
+	if v := t.ContextPath(); v != nil && *v == "-" {
 		return nil, errors.Errorf("context from stdin not allowed in bake")
 	}
 	if v := t.Dockerfile; v != nil && *v == "-" {
 		return nil, errors.Errorf("dockerfile from stdin not allowed in bake")
 	}
 
-	contextPath := "."
-	if t.Context != nil {
-		contextPath = *t.Context
-	}
-	if !strings.HasPrefix(contextPath, "cwd://") && !build.IsRemoteURL(contextPath) {
-		contextPath = path.Clean(contextPath)
-	}
-	dockerfilePath := "Dockerfile"
-	if t.Dockerfile != nil {
-		dockerfilePath = *t.Dockerfile
-	}
-	if !strings.HasPrefix(dockerfilePath, "cwd://") {
-		dockerfilePath = path.Clean(dockerfilePath)
-	}
+	bi := build.Inputs{}
 
-	bi := build.Inputs{
-		ContextPath:    contextPath,
-		DockerfilePath: dockerfilePath,
-		NamedContexts:  toNamedContexts(t.Contexts),
-	}
-	if t.DockerfileInline != nil {
-		bi.DockerfileInline = *t.DockerfileInline
-	}
+	setBuildOptContexts(&bi, t)
 	updateContext(&bi, inp)
+
 	if strings.HasPrefix(bi.DockerfilePath, "cwd://") {
 		// If Dockerfile is local for a remote invocation, we first check if
 		// it's not outside the working directory and then resolve it to an
@@ -1273,7 +1264,7 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	if strings.HasPrefix(bi.ContextPath, "cwd://") {
 		bi.ContextPath = path.Clean(strings.TrimPrefix(bi.ContextPath, "cwd://"))
 	}
-	if !build.IsRemoteURL(bi.ContextPath) && bi.ContextState == nil && !path.IsAbs(bi.DockerfilePath) {
+	if !build.IsRemoteURL(bi.ContextPath) && bi.ContextState == nil && bi.DockerfilePath != "" && !path.IsAbs(bi.DockerfilePath) {
 		bi.DockerfilePath = path.Join(bi.ContextPath, bi.DockerfilePath)
 	}
 	for k, v := range bi.NamedContexts {
@@ -1282,8 +1273,6 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 		}
 	}
 
-	t.Context = &bi.ContextPath
-
 	args := map[string]string{}
 	for k, v := range t.Args {
 		if v == nil {
@@ -1410,6 +1399,43 @@ func toBuildOpt(t *Target, inp *Input) (*build.Options, error) {
 	return bo, nil
 }
 
+func setBuildOptContexts(bi *build.Inputs, t *Target) error {
+	dockerfilePath := "Dockerfile"
+	if t.Dockerfile != nil {
+		dockerfilePath = *t.Dockerfile
+	}
+
+	if !strings.HasPrefix(dockerfilePath, "cwd://") {
+		dockerfilePath = path.Clean(dockerfilePath)
+	}
+	bi.DockerfilePath = dockerfilePath
+
+	if contextPath := t.ContextPath(); contextPath != nil {
+		bi.ContextPath = *contextPath
+		if !strings.HasPrefix(bi.ContextPath, "cwd://") && !build.IsRemoteURL(bi.ContextPath) {
+			bi.ContextPath = path.Clean(bi.ContextPath)
+		}
+
+		if t.DockerfileInline != nil {
+			bi.DockerfileInline = *t.DockerfileInline
+		}
+	} else {
+		bi.ContextPath = "-"
+		if t.DockerfileInline != nil {
+			bi.InStream = build.NewSyncMultiReader(strings.NewReader(*t.DockerfileInline))
+		} else {
+			dockerfile, err := os.ReadFile(bi.DockerfilePath)
+			if err != nil {
+				return err
+			}
+			bi.DockerfilePath = ""
+			bi.InStream = build.NewSyncMultiReader(bytes.NewReader(dockerfile))
+		}
+	}
+	bi.NamedContexts = toNamedContexts(t.Contexts)
+	return nil
+}
+
 func defaultTarget() *Target {
 	return &Target{}
 }
diff --git a/bake/bake_test.go b/bake/bake_test.go
@@ -46,7 +46,7 @@ target "webapp" {
 		require.Equal(t, 1, len(m))
 
 		require.Equal(t, "Dockerfile.webapp", *m["webapp"].Dockerfile)
-		require.Equal(t, ".", *m["webapp"].Context)
+		require.Equal(t, ".", *m["webapp"].ContextPath())
 		require.Equal(t, ptrstr("webDEP"), m["webapp"].Args["VAR_INHERITED"])
 		require.Equal(t, true, *m["webapp"].NoCache)
 		require.Equal(t, "128m", *m["webapp"].ShmSize)
@@ -79,7 +79,7 @@ target "webapp" {
 			require.NoError(t, err)
 
 			require.Equal(t, "Dockerfile.webapp", *m["webapp"].Dockerfile)
-			require.Equal(t, ".", *m["webapp"].Context)
+			require.Equal(t, ".", *m["webapp"].ContextPath())
 
 			_, isSet := m["webapp"].Args["VAR_UNSET"]
 			require.False(t, isSet, m["webapp"].Args["VAR_UNSET"])
@@ -121,7 +121,7 @@ target "webapp" {
 
 		m, g, err := ReadTargets(ctx, []File{fp}, []string{"webapp"}, []string{"webapp.context=foo"}, nil, &EntitlementConf{})
 		require.NoError(t, err)
-		require.Equal(t, "foo", *m["webapp"].Context)
+		require.Equal(t, "foo", *m["webapp"].ContextPath())
 		require.Equal(t, 1, len(g))
 		require.Equal(t, []string{"webapp"}, g["default"].Targets)
 	})
@@ -518,7 +518,7 @@ services:
 
 	require.True(t, ok)
 	require.Equal(t, "Dockerfile.webapp", *m["webapp"].Dockerfile)
-	require.Equal(t, ".", *m["webapp"].Context)
+	require.Equal(t, ".", *m["webapp"].ContextPath())
 	require.Equal(t, ptrstr("1"), m["webapp"].Args["buildno"])
 	require.Equal(t, ptrstr("12"), m["webapp"].Args["buildno2"])
 
@@ -579,7 +579,7 @@ services:
 	_, ok = m["web_app"]
 	require.True(t, ok)
 	require.Equal(t, "Dockerfile.webapp", *m["web_app"].Dockerfile)
-	require.Equal(t, ".", *m["web_app"].Context)
+	require.Equal(t, ".", *m["web_app"].ContextPath())
 	require.Equal(t, ptrstr("1"), m["web_app"].Args["buildno"])
 	require.Equal(t, ptrstr("12"), m["web_app"].Args["buildno2"])
 
@@ -610,7 +610,7 @@ func TestHCLContextCwdPrefix(t *testing.T) {
 	require.Equal(t, 1, len(m))
 	require.Contains(t, m, "app")
 	assert.Equal(t, "test", *m["app"].Dockerfile)
-	assert.Equal(t, "foo", *m["app"].Context)
+	assert.Equal(t, "cwd://foo", *m["app"].ContextPath())
 	assert.Equal(t, "foo/test", bo["app"].Inputs.DockerfilePath)
 	assert.Equal(t, "foo", bo["app"].Inputs.ContextPath)
 }
@@ -641,7 +641,7 @@ func TestHCLDockerfileCwdPrefix(t *testing.T) {
 	require.Equal(t, 1, len(m))
 	require.Contains(t, m, "app")
 	assert.Equal(t, "cwd://Dockerfile.app", *m["app"].Dockerfile)
-	assert.Equal(t, ".", *m["app"].Context)
+	assert.Equal(t, ".", *m["app"].ContextPath())
 	assert.Equal(t, filepath.Join(cwd, "Dockerfile.app"), bo["app"].Inputs.DockerfilePath)
 	assert.Equal(t, ".", bo["app"].Inputs.ContextPath)
 }
@@ -798,9 +798,9 @@ services:
 	require.True(t, ok)
 
 	require.Equal(t, "Dockerfile", *m["app1"].Dockerfile)
-	require.Equal(t, ".", *m["app1"].Context)
+	require.Equal(t, ".", *m["app1"].ContextPath())
 	require.Equal(t, "Dockerfile", *m["app2"].Dockerfile)
-	require.Equal(t, ".", *m["app2"].Context)
+	require.Equal(t, ".", *m["app2"].ContextPath())
 }
 
 func TestReadContextFromTargetChain(t *testing.T) {
@@ -1130,7 +1130,7 @@ services:
 	require.Equal(t, 1, len(g))
 	require.Equal(t, []string{"image", "image-release"}, g["default"].Targets)
 	require.Equal(t, 2, len(m))
-	require.Equal(t, ".", *m["image"].Context)
+	require.Equal(t, ".", *m["image"].ContextPath())
 	require.Equal(t, 1, len(m["image-release"].Outputs))
 	require.Equal(t, "type=image,push=true", m["image-release"].Outputs[0].String())
 
@@ -1139,14 +1139,14 @@ services:
 	require.Equal(t, 1, len(g))
 	require.Equal(t, []string{"image"}, g["default"].Targets)
 	require.Equal(t, 1, len(m))
-	require.Equal(t, ".", *m["image"].Context)
+	require.Equal(t, ".", *m["image"].ContextPath())
 
 	m, g, err = ReadTargets(ctx, []File{fjson}, []string{"default"}, nil, nil, &EntitlementConf{})
 	require.NoError(t, err)
 	require.Equal(t, 1, len(g))
 	require.Equal(t, []string{"image"}, g["default"].Targets)
 	require.Equal(t, 1, len(m))
-	require.Equal(t, ".", *m["image"].Context)
+	require.Equal(t, ".", *m["image"].ContextPath())
 
 	m, g, err = ReadTargets(ctx, []File{fyml}, []string{"default"}, nil, nil, &EntitlementConf{})
 	require.NoError(t, err)
@@ -1172,7 +1172,7 @@ services:
 	sort.Strings(g["default"].Targets)
 	require.Equal(t, []string{"addon", "aws", "image"}, g["default"].Targets)
 	require.Equal(t, 3, len(m))
-	require.Equal(t, ".", *m["image"].Context)
+	require.Equal(t, ".", *m["image"].ContextPath())
 	require.Equal(t, "./Dockerfile", *m["addon"].Dockerfile)
 	require.Equal(t, "./aws.Dockerfile", *m["aws"].Dockerfile)
 }
@@ -1537,7 +1537,7 @@ target "f" {
 			require.Equal(t, tt.targets, g["default"].Targets)
 
 			require.Equal(t, tt.count, len(m))
-			require.Equal(t, ".", *m["d"].Context)
+			require.Equal(t, ".", *m["d"].ContextPath())
 			require.Equal(t, "./testdockerfile", *m["d"].Dockerfile)
 		})
 	}
@@ -1571,7 +1571,7 @@ services:
 	require.Equal(t, "app", c.Targets[0].Name)
 	require.Equal(t, ptrstr("foo"), c.Targets[0].Args["v1"])
 	require.Equal(t, ptrstr("bar"), c.Targets[0].Args["v2"])
-	require.Equal(t, "dir", *c.Targets[0].Context)
+	require.Equal(t, "dir", *c.Targets[0].ContextPath())
 	require.Equal(t, "Dockerfile-alternate", *c.Targets[0].Dockerfile)
 }
 
diff --git a/bake/compose.go b/bake/compose.go
@@ -72,10 +72,10 @@ func ParseCompose(cfgs []composetypes.ConfigFile, envs map[string]string) (*Conf
 				return nil, errors.Wrapf(err, "invalid service name %q", targetName)
 			}
 
-			var contextPathP *string
+			var contextPathP **string
 			if s.Build.Context != "" {
-				contextPath := s.Build.Context
-				contextPathP = &contextPath
+				ptr := &s.Build.Context
+				contextPathP = &ptr
 			}
 			var dockerfilePathP *string
 			if s.Build.Dockerfile != "" {
diff --git a/bake/compose_test.go b/bake/compose_test.go
@@ -65,11 +65,11 @@ secrets:
 		return c.Targets[i].Name < c.Targets[j].Name
 	})
 	require.Equal(t, "db", c.Targets[0].Name)
-	require.Equal(t, "db", *c.Targets[0].Context)
+	require.Equal(t, "db", *c.Targets[0].ContextPath())
 	require.Equal(t, []string{"docker.io/tonistiigi/db"}, c.Targets[0].Tags)
 
 	require.Equal(t, "webapp", c.Targets[1].Name)
-	require.Equal(t, "dir", *c.Targets[1].Context)
+	require.Equal(t, "dir", *c.Targets[1].ContextPath())
 	require.Equal(t, map[string]string{"foo": "bar"}, c.Targets[1].Contexts)
 	require.Equal(t, "Dockerfile-alternate", *c.Targets[1].Dockerfile)
 	require.Equal(t, 1, len(c.Targets[1].Args))
@@ -84,7 +84,7 @@ secrets:
 	}, stringify(c.Targets[1].Secrets))
 
 	require.Equal(t, "webapp2", c.Targets[2].Name)
-	require.Equal(t, "dir", *c.Targets[2].Context)
+	require.Equal(t, "dir", *c.Targets[2].ContextPath())
 	require.Equal(t, "FROM alpine\n", *c.Targets[2].DockerfileInline)
 }
 
diff --git a/bake/hcl_test.go b/bake/hcl_test.go
diff --git a/tests/bake.go b/tests/bake.go

Original file line number	Diff line number	Diff line change
`@@ -72,10 +72,10 @@ func ParseCompose(cfgs []composetypes.ConfigFile, envs map[string]string) (*Conf`
`72`	`72`	`return nil, errors.Wrapf(err, "invalid service name %q", targetName)`
`73`	`73`	`}`
`74`	`74`
`75`		`- var contextPathP *string`
	`75`	`+ var contextPathP **string`
`76`	`76`	`if s.Build.Context != "" {`
`77`		`- contextPath := s.Build.Context`
`78`		`- contextPathP = &contextPath`
	`77`	`+ ptr := &s.Build.Context`
	`78`	`+ contextPathP = &ptr`
`79`	`79`	`}`
`80`	`80`	`var dockerfilePathP *string`
`81`	`81`	`if s.Build.Dockerfile != "" {`