mirror of
https://github.com/mudler/luet.git
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90 lines
2.2 KiB
Go
90 lines
2.2 KiB
Go
// Copyright 2018 Google LLC All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package daemon
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import (
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"bytes"
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"context"
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"io"
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"io/ioutil"
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"sync"
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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/tarball"
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)
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type imageOpener struct {
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ref name.Reference
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ctx context.Context
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buffered bool
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client Client
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once sync.Once
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bytes []byte
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err error
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}
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func (i *imageOpener) saveImage() (io.ReadCloser, error) {
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return i.client.ImageSave(i.ctx, []string{i.ref.Name()})
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}
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func (i *imageOpener) bufferedOpener() (io.ReadCloser, error) {
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// Store the tarball in memory and return a new reader into the bytes each time we need to access something.
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i.once.Do(func() {
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i.bytes, i.err = func() ([]byte, error) {
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rc, err := i.saveImage()
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if err != nil {
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return nil, err
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}
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defer rc.Close()
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return ioutil.ReadAll(rc)
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}()
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})
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// Wrap the bytes in a ReadCloser so it looks like an opened file.
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return ioutil.NopCloser(bytes.NewReader(i.bytes)), i.err
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}
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func (i *imageOpener) opener() tarball.Opener {
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if i.buffered {
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return i.bufferedOpener
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}
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// To avoid storing the tarball in memory, do a save every time we need to access something.
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return i.saveImage
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}
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// Image provides access to an image reference from the Docker daemon,
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// applying functional options to the underlying imageOpener before
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// resolving the reference into a v1.Image.
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func Image(ref name.Reference, options ...Option) (v1.Image, error) {
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o, err := makeOptions(options...)
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if err != nil {
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return nil, err
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}
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i := &imageOpener{
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ref: ref,
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buffered: o.buffered,
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client: o.client,
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ctx: o.ctx,
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}
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return tarball.Image(i.opener(), nil)
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}
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