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Merged
tonistiigi merged 2 commits into from
Jan 16, 2026
Merged

bake: add --var flag for setting variable values #3610

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88359c5
tests: add TestBakeDisableEnvLookup
tonistiigi Jan 16, 2026
c5322ca
bake: add --var flag for setting variable values
tonistiigi Jan 16, 2026
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25 changes: 15 additions & 10 deletions bake/bake.go
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Original file line number Diff line number Diff line change
Expand Up @@ -180,7 +180,7 @@ func readWithProgress(r io.Reader, setStatus func(st *client.VertexStatus)) (dt
}

func ListTargets(files []File) ([]string, error) {
c, _, err := ParseFiles(files, nil)
c, _, err := ParseFiles(files, nil, nil)
if err != nil {
return nil, err
}
Expand All @@ -194,8 +194,8 @@ func ListTargets(files []File) ([]string, error) {
return dedupSlice(targets), nil
}

func ReadTargets(ctx context.Context, files []File, targets, overrides []string, defaults map[string]string, ent *EntitlementConf) (map[string]*Target, map[string]*Group, error) {
c, _, err := ParseFiles(files, defaults)
func ReadTargets(ctx context.Context, files []File, targets, overrides []string, defaults, vars map[string]string, ent *EntitlementConf) (map[string]*Target, map[string]*Group, error) {
c, _, err := ParseFiles(files, defaults, vars)
if err != nil {
return nil, nil, err
}
Expand Down Expand Up @@ -334,7 +334,7 @@ func (c Config) matchNames(pattern string) ([]string, error) {
return names, nil
}

func ParseFiles(files []File, defaults map[string]string) (_ *Config, _ *hclparser.ParseMeta, err error) {
func ParseFiles(files []File, defaults, vars map[string]string) (_ *Config, _ *hclparser.ParseMeta, err error) {
defer func() {
err = formatHCLError(err, files)
}()
Expand All @@ -343,7 +343,7 @@ func ParseFiles(files []File, defaults map[string]string) (_ *Config, _ *hclpars
var composeFiles []File
var hclFiles []*hcl.File
for _, f := range files {
isCompose, composeErr := validateComposeFile(f.Data, f.Name)
isCompose, composeErr := validateComposeFile(f.Data, f.Name, vars)
if isCompose {
if composeErr != nil {
return nil, nil, composeErr
Expand All @@ -366,7 +366,7 @@ func ParseFiles(files []File, defaults map[string]string) (_ *Config, _ *hclpars
}

if len(composeFiles) > 0 {
cfg, cmperr := ParseComposeFiles(composeFiles)
cfg, cmperr := ParseComposeFiles(composeFiles, vars)
if cmperr != nil {
return nil, nil, errors.Wrap(cmperr, "failed to parse compose file")
}
Expand All @@ -376,9 +376,14 @@ func ParseFiles(files []File, defaults map[string]string) (_ *Config, _ *hclpars

var pm hclparser.ParseMeta
if len(hclFiles) > 0 {
lookup := func(string) (string, bool) { return "", false }
if envLookupAllowed() {
lookup = os.LookupEnv
lookup := func(key string) (string, bool) {
if v, ok := vars[key]; ok {
return v, true
}
if envLookupAllowed() {
return os.LookupEnv(key)
}
return "", false
}
res, err := hclparser.Parse(hclparser.MergeFiles(hclFiles), hclparser.Opt{
LookupVar: lookup,
Expand Down Expand Up @@ -430,7 +435,7 @@ func dedupeConfig(c Config) Config {
}

func ParseFile(dt []byte, fn string) (*Config, error) {
c, _, err := ParseFiles([]File{{Data: dt, Name: fn}}, nil)
c, _, err := ParseFiles([]File{{Data: dt, Name: fn}}, nil, nil)
return c, err
}

Expand Down
208 changes: 104 additions & 104 deletions bake/bake_test.go
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12 changes: 7 additions & 5 deletions bake/compose.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package bake
import (
"context"
"fmt"
"maps"
"os"
"path/filepath"
"slices"
Expand All @@ -20,8 +21,8 @@ import (
"go.yaml.in/yaml/v3"
)

func ParseComposeFiles(fs []File) (*Config, error) {
envs, err := composeEnv()
func ParseComposeFiles(fs []File, envOverrides map[string]string) (*Config, error) {
envs, err := composeEnv(envOverrides)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -278,8 +279,8 @@ func loadComposeFiles(cfgs []composetypes.ConfigFile, envs map[string]string, op
})
}

func validateComposeFile(dt []byte, fn string) (bool, error) {
envs, err := composeEnv()
func validateComposeFile(dt []byte, fn string, envOverrides map[string]string) (bool, error) {
envs, err := composeEnv(envOverrides)
if err != nil {
return false, err
}
Expand All @@ -303,7 +304,7 @@ func validateCompose(dt []byte, envs map[string]string) error {
return err
}

func composeEnv() (map[string]string, error) {
func composeEnv(envOverrides map[string]string) (map[string]string, error) {
var env []string
if envLookupAllowed() {
env = os.Environ()
Expand All @@ -315,6 +316,7 @@ func composeEnv() (map[string]string, error) {
return nil, err
}
}
maps.Copy(envs, envOverrides)
return envs, nil
}

Expand Down
16 changes: 8 additions & 8 deletions bake/compose_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -443,7 +443,7 @@ services:
c, err := ParseComposeFiles([]File{{
Name: "docker-compose.yml",
Data: dt,
}})
}}, nil)
require.NoError(t, err)
require.Equal(t, map[string]*string{"FOO": ptrstr("bar")}, c.Targets[0].Args)
}
Expand Down Expand Up @@ -716,7 +716,7 @@ target "default" {
}
for _, tt := range cases {
t.Run(tt.name, func(t *testing.T) {
isCompose, err := validateComposeFile(tt.dt, tt.fn)
isCompose, err := validateComposeFile(tt.dt, tt.fn, nil)
assert.Equal(t, tt.isCompose, isCompose)
if tt.wantErr {
require.Error(t, err)
Expand Down Expand Up @@ -790,7 +790,7 @@ services:
c, err := ParseComposeFiles([]File{{
Name: "composetypes.yml",
Data: dt,
}})
}}, nil)
require.NoError(t, err)

require.Equal(t, 2, len(c.Targets))
Expand Down Expand Up @@ -943,7 +943,7 @@ services:
`)

chdir(t, tmpdir)
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}})
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}}, nil)
require.NoError(t, err)
}

Expand All @@ -968,7 +968,7 @@ services:
t.Setenv("SYSTEM_VALUE", "abc")

chdir(t, tmpdir)
c, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}})
c, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}}, nil)
require.NoError(t, err)
require.Equal(t, map[string]*string{"TEST_VALUE": ptrstr("abc"), "FOO_VALUE": ptrstr("abc")}, c.Targets[0].Args)
}
Expand All @@ -987,7 +987,7 @@ foo:
`)

chdir(t, tmpdir)
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}})
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}}, nil)
require.NoError(t, err)
}

Expand All @@ -1002,15 +1002,15 @@ services:
`)

chdir(t, tmpdir)
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}})
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: dt}}, nil)
require.Error(t, err)
require.ErrorContains(t, err, `additional properties 'foo' not allowed`)
}

func TestEmptyComposeFile(t *testing.T) {
tmpdir := t.TempDir()
chdir(t, tmpdir)
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: []byte(``)}})
_, err := ParseComposeFiles([]File{{Name: "compose.yml", Data: []byte(``)}}, nil)
require.Error(t, err)
require.ErrorContains(t, err, `empty compose file`) // https://github.com/compose-spec/compose-go/blob/a42e7579d813e64c0c1f598a666358bc0c0a0eb4/loader/loader.go#L542
}
Expand Down
27 changes: 14 additions & 13 deletions bake/hcl_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -284,7 +284,7 @@ func TestHCLMultiFileSharedVariables(t *testing.T) {
c, _, err := ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
require.Equal(t, "app", c.Targets[0].Name)
Expand All @@ -296,7 +296,7 @@ func TestHCLMultiFileSharedVariables(t *testing.T) {
c, _, err = ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
Expand Down Expand Up @@ -333,7 +333,7 @@ func TestHCLVarsWithVars(t *testing.T) {
c, _, err := ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
require.Equal(t, "app", c.Targets[0].Name)
Expand All @@ -345,7 +345,7 @@ func TestHCLVarsWithVars(t *testing.T) {
c, _, err = ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
Expand Down Expand Up @@ -914,7 +914,7 @@ func TestHCLMultiFileAttrs(t *testing.T) {
c, _, err := ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
require.Equal(t, "app", c.Targets[0].Name)
Expand All @@ -925,7 +925,7 @@ func TestHCLMultiFileAttrs(t *testing.T) {
c, _, err = ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
Expand All @@ -949,7 +949,7 @@ func TestHCLMultiFileGlobalAttrs(t *testing.T) {
c, _, err := ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
require.Equal(t, "app", c.Targets[0].Name)
Expand Down Expand Up @@ -1133,7 +1133,7 @@ func TestHCLRenameMultiFile(t *testing.T) {
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
{Data: dt3, Name: "c3.hcl"},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 2, len(c.Targets))
Expand Down Expand Up @@ -1351,7 +1351,7 @@ func TestHCLMatrixArgsOverride(t *testing.T) {

c, _, err := ParseFiles([]File{
{Data: dt, Name: "docker-bake.hcl"},
}, map[string]string{"ABC": "11,22,33"})
}, map[string]string{"ABC": "11,22,33"}, nil)
require.NoError(t, err)

require.Equal(t, 3, len(c.Targets))
Expand Down Expand Up @@ -1538,7 +1538,7 @@ services:
c, _, err := ParseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.yml"},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
Expand All @@ -1561,7 +1561,7 @@ func TestHCLBuiltinVars(t *testing.T) {
{Data: dt, Name: "c1.hcl"},
}, map[string]string{
"BAKE_CMD_CONTEXT": "foo",
})
}, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
Expand Down Expand Up @@ -1622,7 +1622,7 @@ target "b" {
}]
}`),
},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Groups))
Expand Down Expand Up @@ -1679,7 +1679,7 @@ target "two" {
Name: "bar.json",
Data: []byte(`{"ABC": "ghi", "DEF": "jkl"}`),
},
}, nil)
}, nil, nil)
require.NoError(t, err)

require.Equal(t, 1, len(c.Groups))
Expand Down Expand Up @@ -2341,6 +2341,7 @@ func TestJSONOverridePriority(t *testing.T) {
c, _, err := ParseFiles(
[]File{{Name: "docker-bake.hcl", Data: dt}},
map[string]string{"FOO_JSON": "whatever"},
nil,
)
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
Expand Down
31 changes: 29 additions & 2 deletions commands/bake.go
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,7 @@ const (
type bakeOptions struct {
files []string
overrides []string
vars []string

sbom string
provenance string
Expand Down Expand Up @@ -209,9 +210,13 @@ func runBake(ctx context.Context, dockerCli command.Cli, targets []string, in ba
"BAKE_CMD_CONTEXT": cmdContext,
"BAKE_LOCAL_PLATFORM": platforms.Format(platforms.DefaultSpec()),
}
vars, err := parseBakeVars(in.vars)
if err != nil {
return err
}

if in.list != "" {
cfg, pm, err := bake.ParseFiles(files, defaults)
cfg, pm, err := bake.ParseFiles(files, defaults, vars)
if err != nil {
return err
}
Expand All @@ -230,7 +235,7 @@ func runBake(ctx context.Context, dockerCli command.Cli, targets []string, in ba
}
}

tgts, grps, err := bake.ReadTargets(ctx, files, targets, overrides, defaults, &ent)
tgts, grps, err := bake.ReadTargets(ctx, files, targets, overrides, defaults, vars, &ent)
if err != nil {
return err
}
Expand Down Expand Up @@ -516,6 +521,7 @@ func bakeCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
flags.StringVar(&options.sbom, "sbom", "", `Shorthand for "--set=*.attest=type=sbom"`)
flags.StringVar(&options.provenance, "provenance", "", `Shorthand for "--set=*.attest=type=provenance"`)
flags.StringArrayVar(&options.overrides, "set", nil, `Override target value (e.g., "targetpattern.key=value")`)
flags.StringArrayVar(&options.vars, "var", nil, `Set a variable value (e.g., "name=value")`)
flags.StringVar(&options.callFunc, "call", "build", `Set method for evaluating build ("check", "outline", "targets")`)
flags.StringArrayVar(&options.allow, "allow", nil, "Allow build to access specified resources")

Expand Down Expand Up @@ -717,6 +723,27 @@ func parseList(input string) (listEntry, error) {
return res, nil
}

func parseBakeVars(values []string) (map[string]string, error) {
if len(values) == 0 {
return nil, nil
}
vars := make(map[string]string, len(values))
for _, value := range values {
if value == "" {
continue
}
key, val, ok := strings.Cut(value, "=")
if !ok {
return nil, errors.Errorf("invalid variable %q, expected key=value", value)
}
if key == "" {
return nil, errors.Errorf("invalid variable %q, key is empty", value)
}
vars[key] = val
}
return vars, nil
}

func printVars(w io.Writer, format string, vars []*hclparser.Variable) error {
slices.SortFunc(vars, func(a, b *hclparser.Variable) int {
return cmp.Compare(a.Name, b.Name)
Expand Down
1 change: 1 addition & 0 deletions docs/reference/buildx_bake.md
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Expand Up @@ -32,6 +32,7 @@ Build from a file
| [`--push`](#push) | `bool` | | Shorthand for `--set=*.output=type=registry`. Conditional. |
| [`--sbom`](#sbom) | `string` | | Shorthand for `--set=*.attest=type=sbom` |
| [`--set`](#set) | `stringArray` | | Override target value (e.g., `targetpattern.key=value`) |
| `--var` | `stringArray` | | Set a variable value (e.g., `name=value`) |

@crazy-max crazy-max Jan 16, 2026

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Could have basic examples similar to set



<!---MARKER_GEN_END-->
Expand Down
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