builder/dockerfile/evaluator.go
// Package dockerfile is the evaluation step in the Dockerfile parse/evaluate pipeline.
//
// It incorporates a dispatch table based on the parser.Node values (see the
// parser package for more information) that are yielded from the parser itself.
// Calling newBuilder with the BuildOpts struct can be used to customize the
// experience for execution purposes only. Parsing is controlled in the parser
// package, and this division of responsibility should be respected.
//
// Please see the jump table targets for the actual invocations, most of which
// will call out to the functions in internals.go to deal with their tasks.
//
// ONBUILD is a special case, which is covered in the onbuild() func in
// dispatchers.go.
//
// The evaluator uses the concept of "steps", which are usually each processable
// line in the Dockerfile. Each step is numbered and certain actions are taken
// before and after each step, such as creating an image ID and removing temporary
// containers and images. Note that ONBUILD creates a kinda-sorta "sub run" which
// includes its own set of steps (usually only one of them).
package dockerfile // import "github.com/docker/docker/builder/dockerfile"
import (
"context"
"reflect"
"strconv"
"strings"
"github.com/docker/docker/api/types/container"
"github.com/docker/docker/builder"
"github.com/docker/docker/errdefs"
"github.com/docker/docker/image"
"github.com/docker/docker/oci"
"github.com/moby/buildkit/frontend/dockerfile/instructions"
"github.com/moby/buildkit/frontend/dockerfile/shell"
"github.com/pkg/errors"
)
func dispatch(ctx context.Context, d dispatchRequest, cmd instructions.Command) (err error) {
if c, ok := cmd.(instructions.PlatformSpecific); ok {
err := c.CheckPlatform(d.state.operatingSystem)
if err != nil {
return errdefs.InvalidParameter(err)
}
}
runConfigEnv := d.state.runConfig.Env
envs := append(runConfigEnv, d.state.buildArgs.FilterAllowed(runConfigEnv)...)
if ex, ok := cmd.(instructions.SupportsSingleWordExpansion); ok {
err := ex.Expand(func(word string) (string, error) {
newword, _, err := d.shlex.ProcessWord(word, envs)
return newword, err
})
if err != nil {
return errdefs.InvalidParameter(err)
}
}
defer func() {
if d.builder.options.ForceRemove {
d.builder.containerManager.RemoveAll(d.builder.Stdout)
return
}
if d.builder.options.Remove && err == nil {
d.builder.containerManager.RemoveAll(d.builder.Stdout)
return
}
}()
switch c := cmd.(type) {
case *instructions.EnvCommand:
return dispatchEnv(ctx, d, c)
case *instructions.MaintainerCommand:
return dispatchMaintainer(ctx, d, c)
case *instructions.LabelCommand:
return dispatchLabel(ctx, d, c)
case *instructions.AddCommand:
return dispatchAdd(ctx, d, c)
case *instructions.CopyCommand:
return dispatchCopy(ctx, d, c)
case *instructions.OnbuildCommand:
return dispatchOnbuild(ctx, d, c)
case *instructions.WorkdirCommand:
return dispatchWorkdir(ctx, d, c)
case *instructions.RunCommand:
return dispatchRun(ctx, d, c)
case *instructions.CmdCommand:
return dispatchCmd(ctx, d, c)
case *instructions.HealthCheckCommand:
return dispatchHealthcheck(ctx, d, c)
case *instructions.EntrypointCommand:
return dispatchEntrypoint(ctx, d, c)
case *instructions.ExposeCommand:
return dispatchExpose(ctx, d, c, envs)
case *instructions.UserCommand:
return dispatchUser(ctx, d, c)
case *instructions.VolumeCommand:
return dispatchVolume(ctx, d, c)
case *instructions.StopSignalCommand:
return dispatchStopSignal(ctx, d, c)
case *instructions.ArgCommand:
return dispatchArg(ctx, d, c)
case *instructions.ShellCommand:
return dispatchShell(ctx, d, c)
}
return errors.Errorf("unsupported command type: %v", reflect.TypeOf(cmd))
}
// dispatchState is a data object which is modified by dispatchers
type dispatchState struct {
runConfig *container.Config
maintainer string
cmdSet bool
imageID string
baseImage builder.Image
stageName string
buildArgs *BuildArgs
operatingSystem string
}
func newDispatchState(baseArgs *BuildArgs) *dispatchState {
args := baseArgs.Clone()
args.ResetAllowed()
return &dispatchState{runConfig: &container.Config{}, buildArgs: args}
}
type stagesBuildResults struct {
flat []*container.Config
indexed map[string]*container.Config
}
func newStagesBuildResults() *stagesBuildResults {
return &stagesBuildResults{
indexed: make(map[string]*container.Config),
}
}
func (r *stagesBuildResults) getByName(name string) (*container.Config, bool) {
c, ok := r.indexed[strings.ToLower(name)]
return c, ok
}
func (r *stagesBuildResults) validateIndex(i int) error {
if i == len(r.flat) {
return errors.New("refers to current build stage")
}
if i < 0 || i > len(r.flat) {
return errors.New("index out of bounds")
}
return nil
}
func (r *stagesBuildResults) get(nameOrIndex string) (*container.Config, error) {
if c, ok := r.getByName(nameOrIndex); ok {
return c, nil
}
ix, err := strconv.ParseInt(nameOrIndex, 10, 0)
if err != nil {
return nil, nil
}
if err := r.validateIndex(int(ix)); err != nil {
return nil, err
}
return r.flat[ix], nil
}
func (r *stagesBuildResults) checkStageNameAvailable(name string) error {
if name != "" {
if _, ok := r.getByName(name); ok {
return errors.Errorf("%s stage name already used", name)
}
}
return nil
}
func (r *stagesBuildResults) commitStage(name string, config *container.Config) error {
if name != "" {
if _, ok := r.getByName(name); ok {
return errors.Errorf("%s stage name already used", name)
}
r.indexed[strings.ToLower(name)] = config
}
r.flat = append(r.flat, config)
return nil
}
func commitStage(state *dispatchState, stages *stagesBuildResults) error {
return stages.commitStage(state.stageName, state.runConfig)
}
type dispatchRequest struct {
state *dispatchState
shlex *shell.Lex
builder *Builder
source builder.Source
stages *stagesBuildResults
}
func newDispatchRequest(builder *Builder, escapeToken rune, source builder.Source, buildArgs *BuildArgs, stages *stagesBuildResults) dispatchRequest {
return dispatchRequest{
state: newDispatchState(buildArgs),
shlex: shell.NewLex(escapeToken),
builder: builder,
source: source,
stages: stages,
}
}
func (s *dispatchState) updateRunConfig() {
s.runConfig.Image = s.imageID
}
// hasFromImage returns true if the builder has processed a `FROM <image>` line
func (s *dispatchState) hasFromImage() bool {
return s.imageID != "" || (s.baseImage != nil && s.baseImage.ImageID() == "")
}
func (s *dispatchState) beginStage(stageName string, img builder.Image) error {
s.stageName = stageName
s.imageID = img.ImageID()
s.operatingSystem = img.OperatingSystem()
if err := image.CheckOS(s.operatingSystem); err != nil {
return err
}
if img.RunConfig() != nil {
// copy avoids referencing the same instance when 2 stages have the same base
s.runConfig = copyRunConfig(img.RunConfig())
} else {
s.runConfig = &container.Config{}
}
s.baseImage = img
s.setDefaultPath()
s.runConfig.OpenStdin = false
s.runConfig.StdinOnce = false
return nil
}
// Add the default PATH to runConfig.ENV if one exists for the operating system and there
// is no PATH set. Note that Windows containers on Windows won't have one as it's set by HCS
func (s *dispatchState) setDefaultPath() {
// TODO(thaJeztah): use github.com/moby/buildkit/util/system.DefaultPathEnv() once https://github.com/moby/buildkit/pull/3158 is resolved.
defaultPath := oci.DefaultPathEnv(s.operatingSystem)
if defaultPath == "" {
return
}
envMap := convertKVStringsToMap(s.runConfig.Env)
if _, ok := envMap["PATH"]; !ok {
s.runConfig.Env = append(s.runConfig.Env, "PATH="+defaultPath)
}
}