dotcloud/docker

package client // import "github.com/docker/docker/client"

import (
    "context"
    "io"
    "net/url"
    "strings"

    "github.com/distribution/reference"
    "github.com/docker/docker/api/types/image"
    "github.com/docker/docker/errdefs"
)

// 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 image.PullOptions) (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))
    }
    if options.Platform != "" {
        query.Set("platform", strings.ToLower(options.Platform))
    }

    resp, err := cli.tryImageCreate(ctx, query, options.RegistryAuth)
    if errdefs.IsUnauthorized(err) && options.PrivilegeFunc != nil {
        newAuthHeader, privilegeErr := options.PrivilegeFunc(ctx)
        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 ""
}