airshipctl/pkg/container/container_docker.go

package container

import (
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"strings"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/container"
	"github.com/docker/docker/api/types/filters"
	"github.com/docker/docker/api/types/network"
	"github.com/docker/docker/client"
)

// DockerClient interface that represents abstract Docker client object
// Interface used as a wrapper for upstream docker client object
type DockerClient interface {
	// ImageInspectWithRaw returns the image information and its raw
	// representation.
	ImageInspectWithRaw(
		context.Context,
		string,
	) (types.ImageInspect, []byte, error)
	// ImageList returns a list of images in the docker host.
	ImageList(
		context.Context,
		types.ImageListOptions,
	) ([]types.ImageSummary, error)
	// ImagePull requests the docker host to pull an image from a remote registry.
	ImagePull(
		context.Context,
		string,
		types.ImagePullOptions,
	) (io.ReadCloser, error)
	// ContainerCreate creates a new container based in the given configuration.
	ContainerCreate(
		context.Context,
		*container.Config,
		*container.HostConfig,
		*network.NetworkingConfig,
		string,
	) (container.ContainerCreateCreatedBody, error)
	// ContainerAttach attaches a connection to a container in the server.
	ContainerAttach(
		context.Context,
		string,
		types.ContainerAttachOptions,
	) (types.HijackedResponse, error)
	//ContainerStart sends a request to the docker daemon to start a container.
	ContainerStart(context.Context, string, types.ContainerStartOptions) error
	// ContainerWait waits until the specified container is in a certain state
	// indicated by the given condition, either "not-running" (default),
	// "next-exit", or "removed".
	ContainerWait(
		context.Context,
		string,
		container.WaitCondition,
	) (<-chan container.ContainerWaitOKBody, <-chan error)
	// ContainerLogs returns the logs generated by a container in an
	// io.ReadCloser.
	ContainerLogs(
		context.Context,
		string,
		types.ContainerLogsOptions,
	) (io.ReadCloser, error)
	// ContainerRemove kills and removes a container from the docker host.
	ContainerRemove(
		context.Context,
		string,
		types.ContainerRemoveOptions,
	) error
}

// DockerContainer docker container object wrapper
type DockerContainer struct {
	tag          string
	imageURL     string
	id           string
	dockerClient DockerClient
	ctx          *context.Context
}

// NewDockerClient returns instance of DockerClient.
// Function essentially returns new Docker API client with default values
func NewDockerClient(ctx *context.Context) (DockerClient, error) {
	cli, err := client.NewClientWithOpts(client.FromEnv)
	if err != nil {
		return nil, err
	}
	cli.NegotiateAPIVersion(*ctx)
	return cli, nil
}

// NewDockerContainer returns instance of DockerContainer object wrapper.
// Function gets container image url, pointer to execution context and
// DockerClient instance.
//
// url format: <image_path>:<tag>. If tag is not specified "latest" is used
// as default value
func NewDockerContainer(ctx *context.Context, url string, cli DockerClient) (*DockerContainer, error) {
	t := "latest"
	nameTag := strings.Split(url, ":")
	if len(nameTag) == 2 {
		t = nameTag[1]
	}

	cnt := &DockerContainer{
		tag:          t,
		imageURL:     url,
		id:           "",
		dockerClient: cli,
		ctx:          ctx,
	}
	if err := cnt.ImagePull(); err != nil {
		return nil, err
	}
	return cnt, nil
}

// getCmd identifies container command. Accepts list of strings each element
// represents command part (e.g "sample cmd --key" should be transformed to
// []string{"sample", "command", "--key"})
//
// If input parameter is NOT empty list method returns input parameter
// immediately
//
// If input parameter is empty list method identifies container image and
// tries to extract Cmd option from this image description (i.e. tries to
// identify default command specified in Dockerfile)
func (c *DockerContainer) getCmd(cmd []string) ([]string, error) {
	if len(cmd) > 0 {
		return cmd, nil
	}

	id, err := c.getImageId(c.imageURL)
	if err != nil {
		return nil, err
	}

	insp, _, err := c.dockerClient.ImageInspectWithRaw(*c.ctx, id)
	if err != nil {
		return nil, err
	}
	config := *insp.Config
	return config.Cmd, nil
}

// getConfig creates configuration structures for Docker API client.
func (c *DockerContainer) getConfig(
	cmd []string,
	volumeMounts []string,
	envVars []string,
) (container.Config, container.HostConfig) {
	cCfg := container.Config{
		Image:       c.imageURL,
		Cmd:         cmd,
		AttachStdin: true,
		OpenStdin:   true,
		Env:         envVars,
	}
	hCfg := container.HostConfig{
		Binds: volumeMounts,
	}
	return cCfg, hCfg
}

// getImageId return ID of container image specified by URL. Method executes
// ImageList function supplied with "reference" filter
func (c *DockerContainer) getImageId(url string) (string, error) {
	kv := filters.KeyValuePair{
		Key:   "reference",
		Value: url,
	}
	filter := filters.NewArgs(kv)
	opts := types.ImageListOptions{
		All:     false,
		Filters: filter,
	}
	img, err := c.dockerClient.ImageList(*c.ctx, opts)
	if err != nil {
		return "", err
	}

	if len(img) == 0 {
		return "", ErrEmptyImageList{}
	}

	return img[0].ID, nil
}

func (c *DockerContainer) GetId() string {
	return c.id
}

// ImagePull downloads image for container
func (c *DockerContainer) ImagePull() error {
	// TODO (D. Ukov) add logic for searching among local images
	// to avoid image download on each execution
	resp, err := c.dockerClient.ImagePull(*c.ctx, c.imageURL, types.ImagePullOptions{})
	if err != nil {
		return err
	}
	// Wait for image is downloaded
	if _, err := ioutil.ReadAll(resp); err != nil {
		return err
	}

	return nil
}

// RunCommand executes specified command in Docker container. Method handles
// container STDIN and volume binds
func (c *DockerContainer) RunCommand(
	cmd []string,
	containerInput io.Reader,
	volumeMounts []string,
	envVars []string,
	// TODO (D. Ukov) add debug logic
	debug bool,
) error {
	realCmd, err := c.getCmd(cmd)
	if err != nil {
		return err
	}

	containerConfig, hostConfig := c.getConfig(realCmd, volumeMounts, envVars)
	resp, err := c.dockerClient.ContainerCreate(
		*c.ctx,
		&containerConfig,
		&hostConfig,
		nil,
		"",
	)
	if err != nil {
		return err
	}

	c.id = resp.ID

	if containerInput != nil {
		conn, attachErr := c.dockerClient.ContainerAttach(*c.ctx, c.id, types.ContainerAttachOptions{
			Stream: true,
			Stdin:  true,
		})
		if attachErr != nil {
			return attachErr
		}
		if _, err = io.Copy(conn.Conn, containerInput); err != nil {
			return err
		}
	}

	if err = c.dockerClient.ContainerStart(*c.ctx, c.id, types.ContainerStartOptions{}); err != nil {
		return err
	}

	statusCh, errCh := c.dockerClient.ContainerWait(*c.ctx, c.id, container.WaitConditionNotRunning)
	select {
	case err = <-errCh:
		if err != nil {
			return err
		}
	case retCode := <-statusCh:
		if retCode.StatusCode != 0 {
			logsCmd := fmt.Sprintf("docker logs %s", c.id)
			return ErrRunContainerCommand{Cmd: logsCmd}
		}
	}

	return nil
}

// RunCommandOutput executes specified command in Docker container and
// returns command output as ReadCloser object. RunCommand debug option is
// set to false explicitly
func (c *DockerContainer) RunCommandOutput(
	cmd []string,
	containerInput io.Reader,
	volumeMounts []string,
	envVars []string,
) (io.ReadCloser, error) {
	if err := c.RunCommand(cmd, containerInput, volumeMounts, envVars, false); err != nil {
		return nil, err
	}

	return c.dockerClient.ContainerLogs(*c.ctx, c.id, types.ContainerLogsOptions{ShowStdout: true})
}

// RmContainer kills and removes a container from the docker host.
func (c *DockerContainer) RmContainer() error {
	return c.dockerClient.ContainerRemove(
		*c.ctx,
		c.id,
		types.ContainerRemoveOptions{
			Force: true,
		},
	)
}