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moby--moby/client/image_pull.go

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package client
import (
"io"
"net/http"
"net/url"
"golang.org/x/net/context"
"github.com/docker/distribution/reference"
"github.com/docker/docker/api/types"
)
// ImagePull requests the docker host to pull an image from a remote registry.
// It executes the privileged function if the operation is unauthorized
// and it tries one more time.
// It's up to the caller to handle the io.ReadCloser and close it properly.
//
// FIXME(vdemeester): there is currently used in a few way in docker/docker
// - if not in trusted content, ref is used to pass the whole reference, and tag is empty
// - if in trusted content, ref is used to pass the reference name, and tag for the digest
func (cli *Client) ImagePull(ctx context.Context, refStr string, options types.ImagePullOptions) (io.ReadCloser, error) {
ref, err := reference.ParseNormalizedNamed(refStr)
if err != nil {
return nil, err
}
query := url.Values{}
query.Set("fromImage", reference.FamiliarName(ref))
if !options.All {
query.Set("tag", getAPITagFromNamedRef(ref))
}
resp, err := cli.tryImageCreate(ctx, query, options.RegistryAuth)
if resp.statusCode == http.StatusUnauthorized && options.PrivilegeFunc != nil {
newAuthHeader, privilegeErr := options.PrivilegeFunc()
if privilegeErr != nil {
return nil, privilegeErr
}
resp, err = cli.tryImageCreate(ctx, query, newAuthHeader)
}
if err != nil {
return nil, err
}
return resp.body, nil
}
// getAPITagFromNamedRef returns a tag from the specified reference.
// This function is necessary as long as the docker "server" api expects
// digests to be sent as tags and makes a distinction between the name
// and tag/digest part of a reference.
func getAPITagFromNamedRef(ref reference.Named) string {
if digested, ok := ref.(reference.Digested); ok {
return digested.Digest().String()
}
ref = reference.TagNameOnly(ref)
if tagged, ok := ref.(reference.Tagged); ok {
return tagged.Tag()
}
return ""
}