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package imagebuilder
import (
"fmt"
"io"
"strings"
"github.com/docker/docker/builder/dockerfile/command"
"github.com/docker/docker/builder/dockerfile/parser"
)
// ParseDockerfile parses the provided stream as a canonical Dockerfile
func ParseDockerfile(r io.Reader) (*parser.Node, error) {
result, err := parser.Parse(r)
if err != nil {
return nil, err
}
return result.AST, nil
}
// Environment variable interpolation will happen on these statements only.
var replaceEnvAllowed = map[string]bool{
command.Env: true,
command.Label: true,
command.Add: true,
command.Copy: true,
command.Workdir: true,
command.Expose: true,
command.Volume: true,
command.User: true,
commandStopSignal: true,
commandArg: true,
}
// Certain commands are allowed to have their args split into more
// words after env var replacements. Meaning:
// ENV foo="123 456"
// EXPOSE $foo
// should result in the same thing as:
// EXPOSE 123 456
// and not treat "123 456" as a single word.
// Note that: EXPOSE "$foo" and EXPOSE $foo are not the same thing.
// Quotes will cause it to still be treated as single word.
var allowWordExpansion = map[string]bool{
command.Expose: true,
}
// Step represents the input Env and the output command after all
// post processing of the command arguments is done.
type Step struct {
Env []string
Command string
Args []string
Flags []string
Attrs map[string]bool
Message string
Original string
}
// Resolve transforms a parsed Dockerfile line into a command to execute,
// resolving any arguments.
//
// 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 statement,
// 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 *Step) Resolve(ast *parser.Node) error {
cmd := ast.Value
upperCasedCmd := strings.ToUpper(cmd)
// To ensure the user is given a decent error message if the platform
// on which the daemon is running does not support a builder command.
if err := platformSupports(strings.ToLower(cmd)); err != nil {
return err
}
attrs := ast.Attributes
original := ast.Original
flags := ast.Flags
strList := []string{}
msg := upperCasedCmd
if len(ast.Flags) > 0 {
msg += " " + strings.Join(ast.Flags, " ")
}
if cmd == "onbuild" {
if ast.Next == nil {
return fmt.Errorf("ONBUILD requires at least one argument")
}
ast = ast.Next.Children[0]
strList = append(strList, ast.Value)
msg += " " + ast.Value
if len(ast.Flags) > 0 {
msg += " " + strings.Join(ast.Flags, " ")
}
}
// count the number of nodes that we are going to traverse first
// so we can pre-create the argument and message array. This speeds up the
// allocation of those list a lot when they have a lot of arguments
cursor := ast
var n int
for cursor.Next != nil {
cursor = cursor.Next
n++
}
msgList := make([]string, n)
var i int
envs := b.Env
for ast.Next != nil {
ast = ast.Next
str := ast.Value
if replaceEnvAllowed[cmd] {
var err error
var words []string
if allowWordExpansion[cmd] {
words, err = ProcessWords(str, envs)
if err != nil {
return err
}
strList = append(strList, words...)
} else {
str, err = ProcessWord(str, envs)
if err != nil {
return err
}
strList = append(strList, str)
}
} else {
strList = append(strList, str)
}
msgList[i] = ast.Value
i++
}
msg += " " + strings.Join(msgList, " ")
b.Message = msg
b.Command = cmd
b.Args = strList
b.Original = original
b.Attrs = attrs
b.Flags = flags
return nil
}
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