214 lines
6.7 KiB
Go
214 lines
6.7 KiB
Go
// builder is the evaluation step in the Dockerfile parse/evaluate pipeline.
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//
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// It incorporates a dispatch table based on the parser.Node values (see the
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// parser package for more information) that are yielded from the parser itself.
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// Calling NewBuilder with the BuildOpts struct can be used to customize the
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// experience for execution purposes only. Parsing is controlled in the parser
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// package, and this division of resposibility should be respected.
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//
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// Please see the jump table targets for the actual invocations, most of which
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// will call out to the functions in internals.go to deal with their tasks.
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//
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// ONBUILD is a special case, which is covered in the onbuild() func in
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// dispatchers.go.
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//
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// The evaluator uses the concept of "steps", which are usually each processable
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// line in the Dockerfile. Each step is numbered and certain actions are taken
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// before and after each step, such as creating an image ID and removing temporary
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// containers and images. Note that ONBUILD creates a kinda-sorta "sub run" which
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// includes its own set of steps (usually only one of them).
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package builder
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import (
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"errors"
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"fmt"
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"io"
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"os"
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"path"
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"strings"
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"github.com/docker/docker/builder/parser"
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"github.com/docker/docker/daemon"
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"github.com/docker/docker/engine"
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"github.com/docker/docker/pkg/tarsum"
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"github.com/docker/docker/registry"
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"github.com/docker/docker/runconfig"
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"github.com/docker/docker/utils"
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)
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var (
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ErrDockerfileEmpty = errors.New("Dockerfile cannot be empty")
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)
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var evaluateTable map[string]func(*Builder, []string, map[string]bool) error
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func init() {
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evaluateTable = map[string]func(*Builder, []string, map[string]bool) error{
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"env": env,
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"maintainer": maintainer,
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"add": add,
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"copy": dispatchCopy, // copy() is a go builtin
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"from": from,
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"onbuild": onbuild,
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"workdir": workdir,
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"docker-version": nullDispatch, // we don't care about docker-version
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"run": run,
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"cmd": cmd,
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"entrypoint": entrypoint,
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"expose": expose,
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"volume": volume,
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"user": user,
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"insert": insert,
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}
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}
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// internal struct, used to maintain configuration of the Dockerfile's
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// processing as it evaluates the parsing result.
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type Builder struct {
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Daemon *daemon.Daemon
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Engine *engine.Engine
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// effectively stdio for the run. Because it is not stdio, I said
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// "Effectively". Do not use stdio anywhere in this package for any reason.
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OutStream io.Writer
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ErrStream io.Writer
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Verbose bool
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UtilizeCache bool
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// controls how images and containers are handled between steps.
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Remove bool
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ForceRemove bool
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AuthConfig *registry.AuthConfig
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AuthConfigFile *registry.ConfigFile
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// Deprecated, original writer used for ImagePull. To be removed.
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OutOld io.Writer
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StreamFormatter *utils.StreamFormatter
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Config *runconfig.Config // runconfig for cmd, run, entrypoint etc.
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// both of these are controlled by the Remove and ForceRemove options in BuildOpts
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TmpContainers map[string]struct{} // a map of containers used for removes
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dockerfile *parser.Node // the syntax tree of the dockerfile
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image string // image name for commit processing
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maintainer string // maintainer name. could probably be removed.
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cmdSet bool // indicates is CMD was set in current Dockerfile
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context *tarsum.TarSum // the context is a tarball that is uploaded by the client
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contextPath string // the path of the temporary directory the local context is unpacked to (server side)
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}
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// Run the builder with the context. This is the lynchpin of this package. This
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// will (barring errors):
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//
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// * call readContext() which will set up the temporary directory and unpack
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// the context into it.
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// * read the dockerfile
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// * parse the dockerfile
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// * walk the parse tree and execute it by dispatching to handlers. If Remove
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// or ForceRemove is set, additional cleanup around containers happens after
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// processing.
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// * Print a happy message and return the image ID.
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//
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func (b *Builder) Run(context io.Reader) (string, error) {
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if err := b.readContext(context); err != nil {
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return "", err
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}
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filename := path.Join(b.contextPath, "Dockerfile")
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fi, err := os.Stat(filename)
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if os.IsNotExist(err) {
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return "", fmt.Errorf("Cannot build a directory without a Dockerfile")
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}
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if fi.Size() == 0 {
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return "", ErrDockerfileEmpty
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}
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f, err := os.Open(filename)
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if err != nil {
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return "", err
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}
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defer f.Close()
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ast, err := parser.Parse(f)
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if err != nil {
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return "", err
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}
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b.dockerfile = ast
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// some initializations that would not have been supplied by the caller.
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b.Config = &runconfig.Config{}
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b.TmpContainers = map[string]struct{}{}
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for i, n := range b.dockerfile.Children {
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if err := b.dispatch(i, n); err != nil {
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if b.ForceRemove {
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b.clearTmp()
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}
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return "", err
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}
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fmt.Fprintf(b.OutStream, " ---> %s\n", utils.TruncateID(b.image))
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if b.Remove {
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b.clearTmp()
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}
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}
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if b.image == "" {
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return "", fmt.Errorf("No image was generated. Is your Dockerfile empty?\n")
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}
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fmt.Fprintf(b.OutStream, "Successfully built %s\n", utils.TruncateID(b.image))
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return b.image, nil
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}
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// This method is the entrypoint to all statement handling routines.
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//
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// Almost all nodes will have this structure:
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// Child[Node, Node, Node] where Child is from parser.Node.Children and each
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// node comes from parser.Node.Next. This forms a "line" with a statement and
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// arguments and we process them in this normalized form by hitting
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// evaluateTable with the leaf nodes of the command and the Builder object.
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//
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// ONBUILD is a special case; in this case the parser will emit:
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// Child[Node, Child[Node, Node...]] where the first node is the literal
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// "onbuild" and the child entrypoint is the command of the ONBUILD statmeent,
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// such as `RUN` in ONBUILD RUN foo. There is special case logic in here to
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// deal with that, at least until it becomes more of a general concern with new
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// features.
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func (b *Builder) dispatch(stepN int, ast *parser.Node) error {
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cmd := ast.Value
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attrs := ast.Attributes
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strs := []string{}
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msg := fmt.Sprintf("Step %d : %s", stepN, strings.ToUpper(cmd))
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if cmd == "onbuild" {
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ast = ast.Next.Children[0]
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strs = append(strs, b.replaceEnv(ast.Value))
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msg += " " + ast.Value
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}
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for ast.Next != nil {
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ast = ast.Next
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strs = append(strs, b.replaceEnv(ast.Value))
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msg += " " + ast.Value
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}
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fmt.Fprintln(b.OutStream, msg)
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// XXX yes, we skip any cmds that are not valid; the parser should have
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// picked these out already.
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if f, ok := evaluateTable[cmd]; ok {
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return f(b, strs, attrs)
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}
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fmt.Fprintf(b.ErrStream, "# Skipping unknown instruction %s\n", strings.ToUpper(cmd))
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return nil
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}
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