// FromImage updates the builder to use the provided image (resetting RunConfig
// and recording the image environment), and updates the node with any ONBUILD
// statements extracted from the parent image.
func (b *Builder) FromImage(image *docker.Image, node *parser.Node) error {
SplitChildren(node, command.From)
b.RunConfig = *image.Config
b.Env = b.RunConfig.Env
b.RunConfig.Env = nil
// Check to see if we have a default PATH, note that windows won't
// have one as its set by HCS
if runtime.GOOS != "windows" && !hasEnvName(b.Env, "PATH") {
b.RunConfig.Env = append(b.RunConfig.Env, "PATH="+defaultPathEnv)
}
// Join the image onbuild statements into node
if image.Config == nil || len(image.Config.OnBuild) == 0 {
return nil
}
extra, err := parser.Parse(bytes.NewBufferString(strings.Join(image.Config.OnBuild, "\n")))
if err != nil {
return err
}
for _, child := range extra.Children {
switch strings.ToUpper(child.Value) {
case "ONBUILD":
return fmt.Errorf("Chaining ONBUILD via `ONBUILD ONBUILD` isn't allowed")
case "MAINTAINER", "FROM":
return fmt.Errorf("%s isn't allowed as an ONBUILD trigger", child.Value)
}
}
node.Children = append(extra.Children, node.Children...)
// Since we've processed the OnBuild statements, clear them from the runconfig state.
b.RunConfig.OnBuild = nil
return nil
}
// SplitChildren removes any children with the provided value from node
// and returns them as an array. node.Children is updated.
func SplitChildren(node *parser.Node, value string) []*parser.Node {
var split []*parser.Node
var children []*parser.Node
for _, child := range node.Children {
if child.Value == value {
split = append(split, child)
} else {
children = append(children, child)
}
}
node.Children = children
return split
}
// InsertInstructions inserts instructions starting from the pos-th child of
// node, moving other children as necessary. The instructions should be valid
// Dockerfile instructions. InsertInstructions mutates node in-place, and the
// final state of node is equivalent to what parser.Parse would return if the
// original Dockerfile represented by node contained the instructions at the
// specified position pos. If the returned error is non-nil, node is guaranteed
// to be unchanged.
func InsertInstructions(node *parser.Node, pos int, instructions string) error {
if node == nil {
return fmt.Errorf("cannot insert instructions in a nil node")
}
if pos < 0 || pos > len(node.Children) {
return fmt.Errorf("pos %d out of range [0, %d]", pos, len(node.Children)-1)
}
newChild, err := parser.Parse(strings.NewReader(instructions))
if err != nil {
return err
}
// InsertVector pattern (https://github.com/golang/go/wiki/SliceTricks)
node.Children = append(node.Children[:pos], append(newChild.Children, node.Children[pos:]...)...)
return nil
}