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transformation.go
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transformation.go
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package transform
import (
"fmt"
"io"
"math"
"os"
"path/filepath"
"reflect"
"strings"
"github.com/tueftler/doget/dockerfile"
"github.com/tueftler/doget/provides"
"github.com/tueftler/doget/use"
)
type Transformation struct {
Input string
Output io.Writer
UseCache bool
}
type Provided map[string]bool
func (p Provided) add(image string) {
p[image] = true
}
func (p Provided) contains(image string) bool {
ok, _ := p[image]
return ok
}
func parse(parser *dockerfile.Parser, input string, file *dockerfile.Dockerfile) error {
if err := parser.ParseFile(input, file); err != nil {
return err
}
if file.From == nil {
return fmt.Errorf("File %q has no `FROM` instruction", input)
}
return nil
}
func load(parser *dockerfile.Parser, input string, file *dockerfile.Dockerfile) error {
stat, err := os.Stat(input)
if err != nil {
return err
}
if stat.IsDir() {
for _, name := range []string{"Dockerfile.in", "Dockerfile"} {
variant := filepath.Join(input, name)
_, err := os.Stat(variant)
if err == nil {
return parse(parser, variant, file)
}
}
return fmt.Errorf("Neither Dockerfile.in or Dockerfile exist in %s", input)
} else {
return parse(parser, input, file)
}
}
// Run transformation
func (t *Transformation) Run(parser *dockerfile.Parser) error {
var file dockerfile.Dockerfile
if err := load(parser, t.Input, &file); err != nil {
return err
}
file.From.Emit(t.Output)
return t.write(parser, &file, "", Provided{file.From.Image: true})
}
func prefix(paths, base string) string {
segments := strings.Split(paths, " ")
result := ""
for _, segment := range segments[0 : len(segments)-1] {
if strings.Contains(segment, "://") {
result += segment + " "
} else {
result += base + segment + " "
}
}
return result + segments[len(segments)-1]
}
func (t *Transformation) write(parser *dockerfile.Parser, file *dockerfile.Dockerfile, base string, provided Provided) error {
fmt.Fprintf(os.Stderr, "Transform : %s\n", file.Source)
for _, statement := range file.Statements {
switch statement.(type) {
case *provides.Statement:
for _, image := range statement.(*provides.Statement).Images() {
provided.add(image)
fmt.Fprintf(os.Stderr, " ---> PROVIDES %s\n", image)
}
break
case *use.Statement:
var path string
origin, err := statement.(*use.Statement).Origin()
if err != nil {
return err
}
path, err = fetch(origin, t.UseCache, func(transferred, total int64) {
percentage := float64(transferred) / float64(total)
finished := int(math.Max(percentage*float64(40), 40))
fmt.Fprintf(
os.Stderr,
"\r ---> Transferring [%s%s] %.2fkB",
strings.Repeat("#", finished),
strings.Repeat("_", 40-finished),
float64(transferred)/float64(1024),
)
})
fmt.Fprintf(os.Stderr, "\n")
if err != nil {
return err
}
var included dockerfile.Dockerfile
if err := load(parser, path, &included); err != nil {
return err
}
if !provided.contains(included.From.Image) {
return fmt.Errorf(
"Include %s requires %s, which was not found in provided %s",
origin.String(),
included.From.Image,
reflect.ValueOf(provided).MapKeys(),
)
}
dockerfile.EmitComment(t.Output, "Included from "+origin.String())
t.write(parser, &included, filepath.ToSlash(path)+"/", provided)
break
// Remove "FROM"
case *dockerfile.From:
break
// Prefix "ADD" paths:
case *dockerfile.Add:
dockerfile.EmitInstruction(t.Output, "ADD", prefix(statement.(*dockerfile.Add).Paths, base))
break
// Prefix "COPY" paths:
case *dockerfile.Copy:
dockerfile.EmitInstruction(t.Output, "COPY", prefix(statement.(*dockerfile.Copy).Paths, base))
break
default:
statement.Emit(t.Output)
break
}
}
return nil
}