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// Copyright 2018 Google LLC All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package random
import (
"archive/tar"
"bytes"
"crypto"
"crypto/rand"
"encoding/hex"
"fmt"
"io"
mrand "math/rand"
"time"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/empty"
"github.com/google/go-containerregistry/pkg/v1/mutate"
"github.com/google/go-containerregistry/pkg/v1/partial"
"github.com/google/go-containerregistry/pkg/v1/types"
)
// uncompressedLayer implements partial.UncompressedLayer from raw bytes.
type uncompressedLayer struct {
diffID v1.Hash
mediaType types.MediaType
content []byte
}
// DiffID implements partial.UncompressedLayer
func (ul *uncompressedLayer) DiffID() (v1.Hash, error) {
return ul.diffID, nil
}
// Uncompressed implements partial.UncompressedLayer
func (ul *uncompressedLayer) Uncompressed() (io.ReadCloser, error) {
return io.NopCloser(bytes.NewBuffer(ul.content)), nil
}
// MediaType returns the media type of the layer
func (ul *uncompressedLayer) MediaType() (types.MediaType, error) {
return ul.mediaType, nil
}
var _ partial.UncompressedLayer = (*uncompressedLayer)(nil)
// Image returns a pseudo-randomly generated Image.
func Image(byteSize, layers int64) (v1.Image, error) {
adds := make([]mutate.Addendum, 0, 5)
for i := int64(0); i < layers; i++ {
layer, err := Layer(byteSize, types.DockerLayer)
if err != nil {
return nil, err
}
adds = append(adds, mutate.Addendum{
Layer: layer,
History: v1.History{
Author: "random.Image",
Comment: fmt.Sprintf("this is a random history %d of %d", i, layers),
CreatedBy: "random",
Created: v1.Time{Time: time.Now()},
},
})
}
return mutate.Append(empty.Image, adds...)
}
// Layer returns a layer with pseudo-randomly generated content.
func Layer(byteSize int64, mt types.MediaType) (v1.Layer, error) {
fileName := fmt.Sprintf("random_file_%d.txt", mrand.Int()) //nolint: gosec
// Hash the contents as we write it out to the buffer.
var b bytes.Buffer
hasher := crypto.SHA256.New()
mw := io.MultiWriter(&b, hasher)
// Write a single file with a random name and random contents.
tw := tar.NewWriter(mw)
if err := tw.WriteHeader(&tar.Header{
Name: fileName,
Size: byteSize,
Typeflag: tar.TypeReg,
}); err != nil {
return nil, err
}
if _, err := io.CopyN(tw, rand.Reader, byteSize); err != nil {
return nil, err
}
if err := tw.Close(); err != nil {
return nil, err
}
h := v1.Hash{
Algorithm: "sha256",
Hex: hex.EncodeToString(hasher.Sum(make([]byte, 0, hasher.Size()))),
}
return partial.UncompressedToLayer(&uncompressedLayer{
diffID: h,
mediaType: mt,
content: b.Bytes(),
})
}
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