422 lines
13 KiB
Go
422 lines
13 KiB
Go
/*
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Package client is a Go client for the Docker Engine API.
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For more information about the Engine API, see the documentation:
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https://docs.docker.com/engine/reference/api/
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Usage
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You use the library by creating a client object and calling methods on it. The
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client can be created either from environment variables with NewEnvClient, or
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configured manually with NewClient.
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For example, to list running containers (the equivalent of "docker ps"):
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package main
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import (
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"context"
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"fmt"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/client"
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)
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func main() {
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cli, err := client.NewEnvClient()
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if err != nil {
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panic(err)
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}
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containers, err := cli.ContainerList(context.Background(), types.ContainerListOptions{})
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if err != nil {
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panic(err)
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}
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for _, container := range containers {
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fmt.Printf("%s %s\n", container.ID[:10], container.Image)
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}
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}
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*/
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package client // import "github.com/docker/docker/client"
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import (
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"context"
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"fmt"
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"net"
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"net/http"
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"net/url"
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"os"
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"path"
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"path/filepath"
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"strings"
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"github.com/docker/docker/api"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/api/types/versions"
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"github.com/docker/go-connections/sockets"
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"github.com/docker/go-connections/tlsconfig"
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"github.com/pkg/errors"
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)
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// ErrRedirect is the error returned by checkRedirect when the request is non-GET.
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var ErrRedirect = errors.New("unexpected redirect in response")
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// Client is the API client that performs all operations
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// against a docker server.
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type Client struct {
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// scheme sets the scheme for the client
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scheme string
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// host holds the server address to connect to
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host string
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// proto holds the client protocol i.e. unix.
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proto string
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// addr holds the client address.
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addr string
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// basePath holds the path to prepend to the requests.
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basePath string
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// client used to send and receive http requests.
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client *http.Client
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// version of the server to talk to.
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version string
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// custom http headers configured by users.
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customHTTPHeaders map[string]string
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// manualOverride is set to true when the version was set by users.
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manualOverride bool
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}
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// CheckRedirect specifies the policy for dealing with redirect responses:
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// If the request is non-GET return `ErrRedirect`. Otherwise use the last response.
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//
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// Go 1.8 changes behavior for HTTP redirects (specifically 301, 307, and 308) in the client .
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// The Docker client (and by extension docker API client) can be made to to send a request
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// like POST /containers//start where what would normally be in the name section of the URL is empty.
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// This triggers an HTTP 301 from the daemon.
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// In go 1.8 this 301 will be converted to a GET request, and ends up getting a 404 from the daemon.
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// This behavior change manifests in the client in that before the 301 was not followed and
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// the client did not generate an error, but now results in a message like Error response from daemon: page not found.
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func CheckRedirect(req *http.Request, via []*http.Request) error {
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if via[0].Method == http.MethodGet {
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return http.ErrUseLastResponse
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}
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return ErrRedirect
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}
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// NewEnvClient initializes a new API client based on environment variables.
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// See FromEnv for a list of support environment variables.
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//
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// Deprecated: use NewClientWithOpts(FromEnv)
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func NewEnvClient() (*Client, error) {
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return NewClientWithOpts(FromEnv)
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}
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// FromEnv configures the client with values from environment variables.
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//
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// Supported environment variables:
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// DOCKER_HOST to set the url to the docker server.
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// DOCKER_API_VERSION to set the version of the API to reach, leave empty for latest.
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// DOCKER_CERT_PATH to load the TLS certificates from.
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// DOCKER_TLS_VERIFY to enable or disable TLS verification, off by default.
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func FromEnv(c *Client) error {
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if dockerCertPath := os.Getenv("DOCKER_CERT_PATH"); dockerCertPath != "" {
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options := tlsconfig.Options{
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CAFile: filepath.Join(dockerCertPath, "ca.pem"),
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CertFile: filepath.Join(dockerCertPath, "cert.pem"),
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KeyFile: filepath.Join(dockerCertPath, "key.pem"),
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InsecureSkipVerify: os.Getenv("DOCKER_TLS_VERIFY") == "",
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}
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tlsc, err := tlsconfig.Client(options)
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if err != nil {
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return err
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}
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c.client = &http.Client{
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Transport: &http.Transport{TLSClientConfig: tlsc},
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CheckRedirect: CheckRedirect,
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}
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}
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if host := os.Getenv("DOCKER_HOST"); host != "" {
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if err := WithHost(host)(c); err != nil {
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return err
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}
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}
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if version := os.Getenv("DOCKER_API_VERSION"); version != "" {
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c.version = version
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c.manualOverride = true
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}
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return nil
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}
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// WithTLSClientConfig applies a tls config to the client transport.
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func WithTLSClientConfig(cacertPath, certPath, keyPath string) func(*Client) error {
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return func(c *Client) error {
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opts := tlsconfig.Options{
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CAFile: cacertPath,
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CertFile: certPath,
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KeyFile: keyPath,
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ExclusiveRootPools: true,
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}
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config, err := tlsconfig.Client(opts)
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if err != nil {
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return errors.Wrap(err, "failed to create tls config")
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}
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if transport, ok := c.client.Transport.(*http.Transport); ok {
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transport.TLSClientConfig = config
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return nil
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}
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return errors.Errorf("cannot apply tls config to transport: %T", c.client.Transport)
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}
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}
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// WithDialer applies the dialer.DialContext to the client transport. This can be
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// used to set the Timeout and KeepAlive settings of the client.
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// Deprecated: use WithDialContext
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func WithDialer(dialer *net.Dialer) func(*Client) error {
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return WithDialContext(dialer.DialContext)
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}
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// WithDialContext applies the dialer to the client transport. This can be
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// used to set the Timeout and KeepAlive settings of the client.
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func WithDialContext(dialContext func(ctx context.Context, network, addr string) (net.Conn, error)) func(*Client) error {
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return func(c *Client) error {
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if transport, ok := c.client.Transport.(*http.Transport); ok {
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transport.DialContext = dialContext
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return nil
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}
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return errors.Errorf("cannot apply dialer to transport: %T", c.client.Transport)
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}
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}
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// WithVersion overrides the client version with the specified one
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func WithVersion(version string) func(*Client) error {
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return func(c *Client) error {
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c.version = version
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return nil
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}
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}
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// WithHost overrides the client host with the specified one.
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func WithHost(host string) func(*Client) error {
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return func(c *Client) error {
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hostURL, err := ParseHostURL(host)
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if err != nil {
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return err
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}
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c.host = host
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c.proto = hostURL.Scheme
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c.addr = hostURL.Host
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c.basePath = hostURL.Path
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if transport, ok := c.client.Transport.(*http.Transport); ok {
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return sockets.ConfigureTransport(transport, c.proto, c.addr)
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}
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return errors.Errorf("cannot apply host to transport: %T", c.client.Transport)
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}
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}
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// WithHTTPClient overrides the client http client with the specified one
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func WithHTTPClient(client *http.Client) func(*Client) error {
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return func(c *Client) error {
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if client != nil {
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c.client = client
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}
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return nil
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}
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}
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// WithHTTPHeaders overrides the client default http headers
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func WithHTTPHeaders(headers map[string]string) func(*Client) error {
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return func(c *Client) error {
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c.customHTTPHeaders = headers
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return nil
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}
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}
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// NewClientWithOpts initializes a new API client with default values. It takes functors
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// to modify values when creating it, like `NewClientWithOpts(WithVersion(…))`
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// It also initializes the custom http headers to add to each request.
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//
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// It won't send any version information if the version number is empty. It is
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// highly recommended that you set a version or your client may break if the
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// server is upgraded.
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func NewClientWithOpts(ops ...func(*Client) error) (*Client, error) {
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client, err := defaultHTTPClient(DefaultDockerHost)
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if err != nil {
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return nil, err
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}
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c := &Client{
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host: DefaultDockerHost,
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version: api.DefaultVersion,
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scheme: "http",
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client: client,
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proto: defaultProto,
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addr: defaultAddr,
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}
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for _, op := range ops {
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if err := op(c); err != nil {
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return nil, err
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}
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}
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if _, ok := c.client.Transport.(http.RoundTripper); !ok {
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return nil, fmt.Errorf("unable to verify TLS configuration, invalid transport %v", c.client.Transport)
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}
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tlsConfig := resolveTLSConfig(c.client.Transport)
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if tlsConfig != nil {
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// TODO(stevvooe): This isn't really the right way to write clients in Go.
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// `NewClient` should probably only take an `*http.Client` and work from there.
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// Unfortunately, the model of having a host-ish/url-thingy as the connection
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// string has us confusing protocol and transport layers. We continue doing
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// this to avoid breaking existing clients but this should be addressed.
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c.scheme = "https"
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}
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return c, nil
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}
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func defaultHTTPClient(host string) (*http.Client, error) {
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url, err := ParseHostURL(host)
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if err != nil {
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return nil, err
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}
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transport := new(http.Transport)
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sockets.ConfigureTransport(transport, url.Scheme, url.Host)
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return &http.Client{
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Transport: transport,
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CheckRedirect: CheckRedirect,
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}, nil
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}
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// NewClient initializes a new API client for the given host and API version.
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// It uses the given http client as transport.
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// It also initializes the custom http headers to add to each request.
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//
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// It won't send any version information if the version number is empty. It is
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// highly recommended that you set a version or your client may break if the
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// server is upgraded.
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// Deprecated: use NewClientWithOpts
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func NewClient(host string, version string, client *http.Client, httpHeaders map[string]string) (*Client, error) {
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return NewClientWithOpts(WithHost(host), WithVersion(version), WithHTTPClient(client), WithHTTPHeaders(httpHeaders))
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}
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// Close the transport used by the client
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func (cli *Client) Close() error {
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if t, ok := cli.client.Transport.(*http.Transport); ok {
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t.CloseIdleConnections()
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}
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return nil
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}
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// getAPIPath returns the versioned request path to call the api.
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// It appends the query parameters to the path if they are not empty.
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func (cli *Client) getAPIPath(p string, query url.Values) string {
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var apiPath string
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if cli.version != "" {
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v := strings.TrimPrefix(cli.version, "v")
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apiPath = path.Join(cli.basePath, "/v"+v, p)
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} else {
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apiPath = path.Join(cli.basePath, p)
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}
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return (&url.URL{Path: apiPath, RawQuery: query.Encode()}).String()
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}
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// ClientVersion returns the API version used by this client.
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func (cli *Client) ClientVersion() string {
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return cli.version
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}
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// NegotiateAPIVersion queries the API and updates the version to match the
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// API version. Any errors are silently ignored.
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func (cli *Client) NegotiateAPIVersion(ctx context.Context) {
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ping, _ := cli.Ping(ctx)
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cli.NegotiateAPIVersionPing(ping)
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}
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// NegotiateAPIVersionPing updates the client version to match the Ping.APIVersion
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// if the ping version is less than the default version.
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func (cli *Client) NegotiateAPIVersionPing(p types.Ping) {
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if cli.manualOverride {
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return
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}
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// try the latest version before versioning headers existed
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if p.APIVersion == "" {
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p.APIVersion = "1.24"
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}
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// if the client is not initialized with a version, start with the latest supported version
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if cli.version == "" {
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cli.version = api.DefaultVersion
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}
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// if server version is lower than the client version, downgrade
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if versions.LessThan(p.APIVersion, cli.version) {
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cli.version = p.APIVersion
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}
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}
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// DaemonHost returns the host address used by the client
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func (cli *Client) DaemonHost() string {
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return cli.host
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}
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// HTTPClient returns a copy of the HTTP client bound to the server
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func (cli *Client) HTTPClient() *http.Client {
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return &*cli.client
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}
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// ParseHostURL parses a url string, validates the string is a host url, and
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// returns the parsed URL
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func ParseHostURL(host string) (*url.URL, error) {
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protoAddrParts := strings.SplitN(host, "://", 2)
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if len(protoAddrParts) == 1 {
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return nil, fmt.Errorf("unable to parse docker host `%s`", host)
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}
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var basePath string
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proto, addr := protoAddrParts[0], protoAddrParts[1]
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if proto == "tcp" {
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parsed, err := url.Parse("tcp://" + addr)
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if err != nil {
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return nil, err
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}
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addr = parsed.Host
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basePath = parsed.Path
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}
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return &url.URL{
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Scheme: proto,
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Host: addr,
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Path: basePath,
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}, nil
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}
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// CustomHTTPHeaders returns the custom http headers stored by the client.
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func (cli *Client) CustomHTTPHeaders() map[string]string {
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m := make(map[string]string)
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for k, v := range cli.customHTTPHeaders {
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m[k] = v
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}
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return m
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}
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// SetCustomHTTPHeaders that will be set on every HTTP request made by the client.
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// Deprecated: use WithHTTPHeaders when creating the client.
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func (cli *Client) SetCustomHTTPHeaders(headers map[string]string) {
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cli.customHTTPHeaders = headers
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}
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// Dialer returns a dialer for a raw stream connection, with HTTP/1.1 header, that can be used for proxying the daemon connection.
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// Used by `docker dial-stdio` (docker/cli#889).
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func (cli *Client) Dialer() func(context.Context) (net.Conn, error) {
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return func(ctx context.Context) (net.Conn, error) {
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if transport, ok := cli.client.Transport.(*http.Transport); ok {
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if transport.DialContext != nil && transport.TLSClientConfig == nil {
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return transport.DialContext(ctx, cli.proto, cli.addr)
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}
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}
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return fallbackDial(cli.proto, cli.addr, resolveTLSConfig(cli.client.Transport))
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}
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}
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