github.com/dctrud/umoci@v0.4.3-0.20191016193643-05a1d37de015/oci/casext/json.go (about)

     1  /*
     2   * umoci: Umoci Modifies Open Containers' Images
     3   * Copyright (C) 2017, 2018 SUSE LLC.
     4   *
     5   * Licensed under the Apache License, Version 2.0 (the "License");
     6   * you may not use this file except in compliance with the License.
     7   * You may obtain a copy of the License at
     8   *
     9   *    http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  
    18  package casext
    19  
    20  import (
    21  	"bytes"
    22  	"encoding/json"
    23  
    24  	"github.com/opencontainers/go-digest"
    25  	"github.com/pkg/errors"
    26  	"golang.org/x/net/context"
    27  )
    28  
    29  // PutBlobJSON adds a new JSON blob to the image (marshalled from the given
    30  // interface). This is equivalent to calling PutBlob() with a JSON payload
    31  // as the reader. Note that due to intricacies in the Go JSON
    32  // implementation, we cannot guarantee that two calls to PutBlobJSON() will
    33  // return the same digest.
    34  //
    35  // TODO: Use a proper JSON serialisation library, which actually guarantees
    36  //       consistent output. Go's JSON library doesn't even attempt to sort
    37  //       map[...]... objects (which have their iteration order randomised in
    38  //       Go).
    39  func (e Engine) PutBlobJSON(ctx context.Context, data interface{}) (digest.Digest, int64, error) {
    40  	var buffer bytes.Buffer
    41  	if err := json.NewEncoder(&buffer).Encode(data); err != nil {
    42  		return "", -1, errors.Wrap(err, "encode JSON")
    43  	}
    44  	return e.PutBlob(ctx, &buffer)
    45  }