mirror of
https://github.com/coder/terraform-provider-envbuilder.git
synced 2025-08-22 17:38:50 +00:00
482a446eb3Addresses some non-blocking comments from #44: - Extracts some of the functions in cached_image_resource.go to separate internal packages tfutil and imgutil. - Some other functions are extracted to helpers.go. - Extracts non-overridable flags to a package-level variable. - Pre-allocates some slices where possible. - Removes some unused code and renames some existing code for readability
103 lines
2.8 KiB
Go
103 lines
2.8 KiB
Go
package imgutil
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import (
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"archive/tar"
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"context"
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"fmt"
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"io"
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"os"
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"path/filepath"
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"github.com/coder/envbuilder/constants"
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"github.com/google/go-containerregistry/pkg/authn"
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"github.com/google/go-containerregistry/pkg/name"
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v1 "github.com/google/go-containerregistry/pkg/v1"
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"github.com/google/go-containerregistry/pkg/v1/remote"
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"github.com/hashicorp/terraform-plugin-log/tflog"
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)
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// GetRemoteImage fetches the image manifest of the image.
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func GetRemoteImage(imgRef string) (v1.Image, error) {
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ref, err := name.ParseReference(imgRef)
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if err != nil {
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return nil, fmt.Errorf("parse reference: %w", err)
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}
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img, err := remote.Image(ref, remote.WithAuthFromKeychain(authn.DefaultKeychain))
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if err != nil {
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return nil, fmt.Errorf("check remote image: %w", err)
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}
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return img, nil
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}
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// ExtractEnvbuilderFromImage reads the image located at imgRef and extracts
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// MagicBinaryLocation to destPath.
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func ExtractEnvbuilderFromImage(ctx context.Context, imgRef, destPath string) error {
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needle := filepath.Clean(constants.MagicBinaryLocation)[1:] // skip leading '/'
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img, err := GetRemoteImage(imgRef)
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if err != nil {
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return fmt.Errorf("check remote image: %w", err)
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}
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layers, err := img.Layers()
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if err != nil {
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return fmt.Errorf("get image layers: %w", err)
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}
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// Check the layers in reverse order. The last layers are more likely to
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// include the binary.
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for i := len(layers) - 1; i >= 0; i-- {
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ul, err := layers[i].Uncompressed()
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if err != nil {
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return fmt.Errorf("get uncompressed layer: %w", err)
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}
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tr := tar.NewReader(ul)
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for {
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th, err := tr.Next()
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if err == io.EOF {
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break
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}
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if err != nil {
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return fmt.Errorf("read tar header: %w", err)
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}
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name := filepath.Clean(th.Name)
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if th.Typeflag != tar.TypeReg {
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tflog.Debug(ctx, "skip non-regular file", map[string]any{"name": name, "layer_idx": i + 1})
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continue
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}
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if name != needle {
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tflog.Debug(ctx, "skip file", map[string]any{"name": name, "layer_idx": i + 1})
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continue
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}
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tflog.Debug(ctx, "found file", map[string]any{"name": name, "layer_idx": i + 1})
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if err := os.MkdirAll(filepath.Dir(destPath), 0o755); err != nil {
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return fmt.Errorf("create parent directories: %w", err)
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}
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destF, err := os.Create(destPath)
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if err != nil {
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return fmt.Errorf("create dest file for writing: %w", err)
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}
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defer destF.Close()
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_, err = io.Copy(destF, tr)
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if err != nil {
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return fmt.Errorf("copy dest file from image: %w", err)
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}
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if err := destF.Close(); err != nil {
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return fmt.Errorf("close dest file: %w", err)
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}
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if err := os.Chmod(destPath, 0o755); err != nil {
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return fmt.Errorf("chmod file: %w", err)
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}
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return nil
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}
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}
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return fmt.Errorf("extract envbuilder binary from image %q: %w", imgRef, os.ErrNotExist)
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}
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