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moby--moby/builder/evaluator.go
Erik Hollensbe 4e74cd498b builder: whitelist verbs useful for environment replacement.
Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
2014-10-27 17:38:25 +00:00

236 lines
7.1 KiB
Go

// builder 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 resposibility 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 builder
import (
"errors"
"fmt"
"io"
"os"
"path"
"strings"
log "github.com/Sirupsen/logrus"
"github.com/docker/docker/builder/parser"
"github.com/docker/docker/daemon"
"github.com/docker/docker/engine"
"github.com/docker/docker/pkg/tarsum"
"github.com/docker/docker/registry"
"github.com/docker/docker/runconfig"
"github.com/docker/docker/utils"
)
var (
ErrDockerfileEmpty = errors.New("Dockerfile cannot be empty")
)
// Environment variable interpolation will happen on these statements only.
var replaceEnvAllowed = map[string]struct{}{
"env": {},
"add": {},
"copy": {},
"workdir": {},
"expose": {},
"volume": {},
"user": {},
}
var evaluateTable map[string]func(*Builder, []string, map[string]bool, string) error
func init() {
evaluateTable = map[string]func(*Builder, []string, map[string]bool, string) error{
"env": env,
"maintainer": maintainer,
"add": add,
"copy": dispatchCopy, // copy() is a go builtin
"from": from,
"onbuild": onbuild,
"workdir": workdir,
"run": run,
"cmd": cmd,
"entrypoint": entrypoint,
"expose": expose,
"volume": volume,
"user": user,
"insert": insert,
}
}
// internal struct, used to maintain configuration of the Dockerfile's
// processing as it evaluates the parsing result.
type Builder struct {
Daemon *daemon.Daemon
Engine *engine.Engine
// effectively stdio for the run. Because it is not stdio, I said
// "Effectively". Do not use stdio anywhere in this package for any reason.
OutStream io.Writer
ErrStream io.Writer
Verbose bool
UtilizeCache bool
// controls how images and containers are handled between steps.
Remove bool
ForceRemove bool
AuthConfig *registry.AuthConfig
AuthConfigFile *registry.ConfigFile
// Deprecated, original writer used for ImagePull. To be removed.
OutOld io.Writer
StreamFormatter *utils.StreamFormatter
Config *runconfig.Config // runconfig for cmd, run, entrypoint etc.
// both of these are controlled by the Remove and ForceRemove options in BuildOpts
TmpContainers map[string]struct{} // a map of containers used for removes
dockerfile *parser.Node // the syntax tree of the dockerfile
image string // image name for commit processing
maintainer string // maintainer name. could probably be removed.
cmdSet bool // indicates is CMD was set in current Dockerfile
context tarsum.TarSum // the context is a tarball that is uploaded by the client
contextPath string // the path of the temporary directory the local context is unpacked to (server side)
}
// Run the builder with the context. This is the lynchpin of this package. This
// will (barring errors):
//
// * call readContext() which will set up the temporary directory and unpack
// the context into it.
// * read the dockerfile
// * parse the dockerfile
// * walk the parse tree and execute it by dispatching to handlers. If Remove
// or ForceRemove is set, additional cleanup around containers happens after
// processing.
// * Print a happy message and return the image ID.
//
func (b *Builder) Run(context io.Reader) (string, error) {
if err := b.readContext(context); err != nil {
return "", err
}
defer func() {
if err := os.RemoveAll(b.contextPath); err != nil {
log.Debugf("[BUILDER] failed to remove temporary context: %s", err)
}
}()
filename := path.Join(b.contextPath, "Dockerfile")
fi, err := os.Stat(filename)
if os.IsNotExist(err) {
return "", fmt.Errorf("Cannot build a directory without a Dockerfile")
}
if fi.Size() == 0 {
return "", ErrDockerfileEmpty
}
f, err := os.Open(filename)
if err != nil {
return "", err
}
defer f.Close()
ast, err := parser.Parse(f)
if err != nil {
return "", err
}
b.dockerfile = ast
// some initializations that would not have been supplied by the caller.
b.Config = &runconfig.Config{}
b.TmpContainers = map[string]struct{}{}
for i, n := range b.dockerfile.Children {
if err := b.dispatch(i, n); err != nil {
if b.ForceRemove {
b.clearTmp()
}
return "", err
}
fmt.Fprintf(b.OutStream, " ---> %s\n", utils.TruncateID(b.image))
if b.Remove {
b.clearTmp()
}
}
if b.image == "" {
return "", fmt.Errorf("No image was generated. Is your Dockerfile empty?\n")
}
fmt.Fprintf(b.OutStream, "Successfully built %s\n", utils.TruncateID(b.image))
return b.image, nil
}
// This method is the entrypoint to all statement handling routines.
//
// Almost all nodes will have this structure:
// Child[Node, Node, Node] where Child is from parser.Node.Children and each
// node comes from parser.Node.Next. This forms a "line" with a statement and
// arguments and we process them in this normalized form by hitting
// evaluateTable with the leaf nodes of the command and the Builder object.
//
// ONBUILD is a special case; in this case the parser will emit:
// Child[Node, Child[Node, Node...]] where the first node is the literal
// "onbuild" and the child entrypoint is the command of the ONBUILD statmeent,
// such as `RUN` in ONBUILD RUN foo. There is special case logic in here to
// deal with that, at least until it becomes more of a general concern with new
// features.
func (b *Builder) dispatch(stepN int, ast *parser.Node) error {
cmd := ast.Value
attrs := ast.Attributes
original := ast.Original
strs := []string{}
msg := fmt.Sprintf("Step %d : %s", stepN, strings.ToUpper(cmd))
if cmd == "onbuild" {
ast = ast.Next.Children[0]
strs = append(strs, ast.Value)
msg += " " + ast.Value
}
for ast.Next != nil {
ast = ast.Next
var str string
str = ast.Value
if _, ok := replaceEnvAllowed[cmd]; ok {
str = b.replaceEnv(ast.Value)
}
strs = append(strs, str)
msg += " " + ast.Value
}
fmt.Fprintln(b.OutStream, msg)
// XXX yes, we skip any cmds that are not valid; the parser should have
// picked these out already.
if f, ok := evaluateTable[cmd]; ok {
return f(b, strs, attrs, original)
}
fmt.Fprintf(b.ErrStream, "# Skipping unknown instruction %s\n", strings.ToUpper(cmd))
return nil
}