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bake: allow variables to reference each other
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Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
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@tonistiigi
tonistiigi committed Feb 10, 2021
1 parent 8944a02 commit 2ae79c5
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Showing 3 changed files with 245 additions and 17 deletions.
4 changes: 2 additions & 2 deletions bake/bake.go
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Original file line number Diff line number Diff line change
Expand Up @@ -402,8 +402,8 @@ func (c Config) target(name string, visited map[string]struct{}, overrides map[s
}

type Variable struct {
Name string `json:"-" hcl:"name,label"`
Default string `json:"default,omitempty" hcl:"default,optional"`
Name string `json:"-" hcl:"name,label"`
Default *hcl.Attribute `json:"default,omitempty" hcl:"default,optional"`
}

type Group struct {
Expand Down
140 changes: 125 additions & 15 deletions bake/hcl.go
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Original file line number Diff line number Diff line change
@@ -1,7 +1,10 @@
package bake

import (
"math"
"math/big"
"os"
"strconv"
"strings"

"github.com/hashicorp/go-cty-funcs/cidr"
Expand All @@ -17,6 +20,7 @@ import (
hcljson "github.com/hashicorp/hcl/v2/json"
"github.com/moby/buildkit/solver/errdefs"
"github.com/moby/buildkit/solver/pb"
"github.com/pkg/errors"
"github.com/zclconf/go-cty/cty"
"github.com/zclconf/go-cty/cty/function"
"github.com/zclconf/go-cty/cty/function/stdlib"
Expand Down Expand Up @@ -125,11 +129,14 @@ var (
}
)

// Used in the first pass of decoding instead of the Config struct to disallow
// interpolation while parsing variable blocks.
type StaticConfig struct {
Variables []*Variable `hcl:"variable,block"`
Remain hcl.Body `hcl:",remain"`

defaults map[string]*hcl.Attribute
env map[string]string
values map[string]cty.Value
progress map[string]struct{}
}

func mergeStaticConfig(scs []*StaticConfig) *StaticConfig {
Expand All @@ -143,6 +150,118 @@ func mergeStaticConfig(scs []*StaticConfig) *StaticConfig {
return sc
}

func (sc *StaticConfig) Values(withEnv bool) (map[string]cty.Value, error) {
sc.defaults = map[string]*hcl.Attribute{}
for _, v := range sc.Variables {
sc.defaults[v.Name] = v.Default
}

sc.env = map[string]string{}
if withEnv {
// Override default with values from environment.
for _, v := range os.Environ() {
parts := strings.SplitN(v, "=", 2)
name, value := parts[0], parts[1]
sc.env[name] = value
}
}

sc.values = map[string]cty.Value{}
sc.progress = map[string]struct{}{}

for k := range sc.defaults {
if _, err := sc.resolveValue(k); err != nil {
return nil, err
}
}
return sc.values, nil
}

func (sc *StaticConfig) resolveValue(name string) (v *cty.Value, err error) {
if v, ok := sc.values[name]; ok {
return &v, nil
}
if _, ok := sc.progress[name]; ok {
return nil, errors.Errorf("variable cycle not allowed")
}
sc.progress[name] = struct{}{}

defer func() {
if v != nil {
sc.values[name] = *v
}
}()

def, ok := sc.defaults[name]

if !ok {
return nil, errors.Errorf("undefined variable %q", name)
}

if def == nil {
v := cty.StringVal(sc.env[name])
return &v, nil
}

ectx := &hcl.EvalContext{
Variables: map[string]cty.Value{},
Functions: stdlibFunctions, // user functions not possible atm
}
for _, v := range def.Expr.Variables() {
value, err := sc.resolveValue(v.RootName())
if err != nil {
var diags hcl.Diagnostics
if !errors.As(err, &diags) {
return nil, err
}
r := v.SourceRange()
return nil, hcl.Diagnostics{
&hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Invalid expression",
Detail: err.Error(),
Subject: &r,
Context: &r,
},
}
}
ectx.Variables[v.RootName()] = *value
}

vv, diags := def.Expr.Value(ectx)
if diags.HasErrors() {
return nil, diags
}

if envv, ok := sc.env[name]; ok {
if vv.Type().Equals(cty.Bool) {
b, err := strconv.ParseBool(envv)
if err != nil {
return nil, errors.Wrapf(err, "failed to parse %s as bool", name)
}
v := cty.BoolVal(b)
return &v, nil
} else if vv.Type().Equals(cty.String) {
v := cty.StringVal(envv)
return &v, nil
} else if vv.Type().Equals(cty.Number) {
n, err := strconv.ParseFloat(envv, 64)
if err == nil && (math.IsNaN(n) || math.IsInf(n, 0)) {
err = errors.Errorf("invalid number value")
}
if err != nil {
return nil, errors.Wrapf(err, "failed to parse %s as number", name)
}
v := cty.NumberVal(big.NewFloat(n))
return &v, nil
} else {
// TODO: support lists with csv values
return nil, errors.Errorf("unsupported type %s for variable %s", v.Type(), name)
}
}
return &vv, nil
}

func ParseHCLFile(dt []byte, fn string) (*hcl.File, *StaticConfig, error) {
if strings.HasSuffix(fn, ".json") || strings.HasSuffix(fn, ".hcl") {
return parseHCLFile(dt, fn)
Expand Down Expand Up @@ -189,10 +308,10 @@ func parseHCLFile(dt []byte, fn string) (f *hcl.File, _ *StaticConfig, err error

func ParseHCL(b hcl.Body, sc *StaticConfig) (_ *Config, err error) {

// Set all variables to their default value if defined.
variables := make(map[string]cty.Value)
for _, variable := range sc.Variables {
variables[variable.Name] = cty.StringVal(variable.Default)
// evaluate variables
variables, err := sc.Values(true)
if err != nil {
return nil, err
}

userFunctions, _, diags := userfunc.DecodeUserFunctions(b, "function", func() *hcl.EvalContext {
Expand All @@ -205,15 +324,6 @@ func ParseHCL(b hcl.Body, sc *StaticConfig) (_ *Config, err error) {
return nil, diags
}

// Override default with values from environment.
for _, env := range os.Environ() {
parts := strings.SplitN(env, "=", 2)
name, value := parts[0], parts[1]
if _, ok := variables[name]; ok {
variables[name] = cty.StringVal(value)
}
}

functions := make(map[string]function.Function)
for k, v := range stdlibFunctions {
functions[k] = v
Expand Down
118 changes: 118 additions & 0 deletions bake/hcl_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -323,3 +323,121 @@ func TestHCLMultiFileSharedVariables(t *testing.T) {
require.Equal(t, "pre-def", c.Targets[0].Args["v1"])
require.Equal(t, "def-post", c.Targets[0].Args["v2"])
}

func TestHCLVarsWithVars(t *testing.T) {
os.Unsetenv("FOO")
dt := []byte(`
variable "FOO" {
default = upper("${BASE}def")
}
variable "BAR" {
default = "-${FOO}-"
}
target "app" {
args = {
v1 = "pre-${BAR}"
}
}
`)
dt2 := []byte(`
variable "BASE" {
default = "abc"
}
target "app" {
args = {
v2 = "${FOO}-post"
}
}
`)

c, err := parseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
})
require.NoError(t, err)
require.Equal(t, 1, len(c.Targets))
require.Equal(t, c.Targets[0].Name, "app")
require.Equal(t, "pre--ABCDEF-", c.Targets[0].Args["v1"])
require.Equal(t, "ABCDEF-post", c.Targets[0].Args["v2"])

os.Setenv("BASE", "new")

c, err = parseFiles([]File{
{Data: dt, Name: "c1.hcl"},
{Data: dt2, Name: "c2.hcl"},
})
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
require.Equal(t, c.Targets[0].Name, "app")
require.Equal(t, "pre--NEWDEF-", c.Targets[0].Args["v1"])
require.Equal(t, "NEWDEF-post", c.Targets[0].Args["v2"])
}

func TestHCLTypedVariables(t *testing.T) {
os.Unsetenv("FOO")
dt := []byte(`
variable "FOO" {
default = 3
}
variable "IS_FOO" {
default = true
}
target "app" {
args = {
v1 = FOO > 5 ? "higher" : "lower"
v2 = IS_FOO ? "yes" : "no"
}
}
`)

c, err := ParseFile(dt, "docker-bake.hcl")
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
require.Equal(t, c.Targets[0].Name, "app")
require.Equal(t, "lower", c.Targets[0].Args["v1"])
require.Equal(t, "yes", c.Targets[0].Args["v2"])

os.Setenv("FOO", "5.1")
os.Setenv("IS_FOO", "0")

c, err = ParseFile(dt, "docker-bake.hcl")
require.NoError(t, err)

require.Equal(t, 1, len(c.Targets))
require.Equal(t, c.Targets[0].Name, "app")
require.Equal(t, "higher", c.Targets[0].Args["v1"])
require.Equal(t, "no", c.Targets[0].Args["v2"])

os.Setenv("FOO", "NaN")
c, err = ParseFile(dt, "docker-bake.hcl")
require.Error(t, err)
require.Contains(t, err.Error(), "failed to parse FOO as number")

os.Setenv("FOO", "0")
os.Setenv("IS_FOO", "maybe")

c, err = ParseFile(dt, "docker-bake.hcl")
require.Error(t, err)
require.Contains(t, err.Error(), "failed to parse IS_FOO as bool")
}

func TestHCLVariableCycle(t *testing.T) {
dt := []byte(`
variable "FOO" {
default = BAR
}
variable "FOO2" {
default = FOO
}
variable "BAR" {
default = FOO
}
target "app" {}
`)

_, err := ParseFile(dt, "docker-bake.hcl")
require.Error(t, err)
require.Contains(t, err.Error(), "variable cycle not allowed")
}

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