terraform-provider-envbuilder/internal/imgutil/imgutil.go
Cian Johnston 4077a87dca
fix: set MagicDir to tempdir when performing cache probe ()
* fix: set MagicDir to tempdir when performing cache probe

* chore: update envbuilder to b7781d8

* imgutil: get default envbuilder binary path from envbuilder options
2024-09-10 09:47:39 +01:00

106 lines
2.8 KiB
Go

package imgutil
import (
"archive/tar"
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
eboptions "github.com/coder/envbuilder/options"
"github.com/google/go-containerregistry/pkg/authn"
"github.com/google/go-containerregistry/pkg/name"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/remote"
"github.com/hashicorp/terraform-plugin-log/tflog"
)
// GetRemoteImage fetches the image manifest of the image.
func GetRemoteImage(imgRef string) (v1.Image, error) {
ref, err := name.ParseReference(imgRef)
if err != nil {
return nil, fmt.Errorf("parse reference: %w", err)
}
img, err := remote.Image(ref, remote.WithAuthFromKeychain(authn.DefaultKeychain))
if err != nil {
return nil, fmt.Errorf("check remote image: %w", err)
}
return img, nil
}
// ExtractEnvbuilderFromImage reads the image located at imgRef and extracts
// MagicBinaryLocation to destPath.
func ExtractEnvbuilderFromImage(ctx context.Context, imgRef, destPath string) error {
var o eboptions.Options
o.SetDefaults()
needle := strings.TrimPrefix(o.BinaryPath, "/")
img, err := GetRemoteImage(imgRef)
if err != nil {
return fmt.Errorf("check remote image: %w", err)
}
layers, err := img.Layers()
if err != nil {
return fmt.Errorf("get image layers: %w", err)
}
// Check the layers in reverse order. The last layers are more likely to
// include the binary.
for i := len(layers) - 1; i >= 0; i-- {
ul, err := layers[i].Uncompressed()
if err != nil {
return fmt.Errorf("get uncompressed layer: %w", err)
}
tr := tar.NewReader(ul)
for {
th, err := tr.Next()
if err == io.EOF {
break
}
if err != nil {
return fmt.Errorf("read tar header: %w", err)
}
name := filepath.Clean(th.Name)
if th.Typeflag != tar.TypeReg {
tflog.Debug(ctx, "skip non-regular file", map[string]any{"name": name, "layer_idx": i + 1})
continue
}
if name != needle {
tflog.Debug(ctx, "skip file", map[string]any{"name": name, "layer_idx": i + 1})
continue
}
tflog.Debug(ctx, "found file", map[string]any{"name": name, "layer_idx": i + 1})
if err := os.MkdirAll(filepath.Dir(destPath), 0o755); err != nil {
return fmt.Errorf("create parent directories: %w", err)
}
destF, err := os.Create(destPath)
if err != nil {
return fmt.Errorf("create dest file for writing: %w", err)
}
defer destF.Close()
_, err = io.Copy(destF, tr)
if err != nil {
return fmt.Errorf("copy dest file from image: %w", err)
}
if err := destF.Close(); err != nil {
return fmt.Errorf("close dest file: %w", err)
}
if err := os.Chmod(destPath, 0o755); err != nil {
return fmt.Errorf("chmod file: %w", err)
}
return nil
}
}
return fmt.Errorf("extract envbuilder binary from image %q: %w", imgRef, os.ErrNotExist)
}