github.com/adityamillind98/moby@v23.0.0-rc.4+incompatible/daemon/cluster/services.go (about)

     1  package cluster // import "github.com/docker/docker/daemon/cluster"
     2  
     3  import (
     4  	"context"
     5  	"encoding/base64"
     6  	"encoding/json"
     7  	"fmt"
     8  	"io"
     9  	"os"
    10  	"strconv"
    11  	"strings"
    12  	"time"
    13  
    14  	"github.com/docker/distribution/reference"
    15  	apitypes "github.com/docker/docker/api/types"
    16  	"github.com/docker/docker/api/types/backend"
    17  	types "github.com/docker/docker/api/types/swarm"
    18  	timetypes "github.com/docker/docker/api/types/time"
    19  	"github.com/docker/docker/daemon/cluster/convert"
    20  	"github.com/docker/docker/errdefs"
    21  	runconfigopts "github.com/docker/docker/runconfig/opts"
    22  	gogotypes "github.com/gogo/protobuf/types"
    23  	swarmapi "github.com/moby/swarmkit/v2/api"
    24  	"github.com/pkg/errors"
    25  	"github.com/sirupsen/logrus"
    26  	"google.golang.org/grpc"
    27  )
    28  
    29  // GetServices returns all services of a managed swarm cluster.
    30  func (c *Cluster) GetServices(options apitypes.ServiceListOptions) ([]types.Service, error) {
    31  	c.mu.RLock()
    32  	defer c.mu.RUnlock()
    33  
    34  	state := c.currentNodeState()
    35  	if !state.IsActiveManager() {
    36  		return nil, c.errNoManager(state)
    37  	}
    38  
    39  	// We move the accepted filter check here as "mode" filter
    40  	// is processed in the daemon, not in SwarmKit. So it might
    41  	// be good to have accepted file check in the same file as
    42  	// the filter processing (in the for loop below).
    43  	accepted := map[string]bool{
    44  		"name":    true,
    45  		"id":      true,
    46  		"label":   true,
    47  		"mode":    true,
    48  		"runtime": true,
    49  	}
    50  	if err := options.Filters.Validate(accepted); err != nil {
    51  		return nil, err
    52  	}
    53  
    54  	if len(options.Filters.Get("runtime")) == 0 {
    55  		// Default to using the container runtime filter
    56  		options.Filters.Add("runtime", string(types.RuntimeContainer))
    57  	}
    58  
    59  	filters := &swarmapi.ListServicesRequest_Filters{
    60  		NamePrefixes: options.Filters.Get("name"),
    61  		IDPrefixes:   options.Filters.Get("id"),
    62  		Labels:       runconfigopts.ConvertKVStringsToMap(options.Filters.Get("label")),
    63  		Runtimes:     options.Filters.Get("runtime"),
    64  	}
    65  
    66  	ctx, cancel := c.getRequestContext()
    67  	defer cancel()
    68  
    69  	r, err := state.controlClient.ListServices(
    70  		ctx,
    71  		&swarmapi.ListServicesRequest{Filters: filters},
    72  		grpc.MaxCallRecvMsgSize(defaultRecvSizeForListResponse),
    73  	)
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  
    78  	services := make([]types.Service, 0, len(r.Services))
    79  
    80  	// if the  user requests the service statuses, we'll store the IDs needed
    81  	// in this slice
    82  	var serviceIDs []string
    83  	if options.Status {
    84  		serviceIDs = make([]string, 0, len(r.Services))
    85  	}
    86  	for _, service := range r.Services {
    87  		if options.Filters.Contains("mode") {
    88  			var mode string
    89  			switch service.Spec.GetMode().(type) {
    90  			case *swarmapi.ServiceSpec_Global:
    91  				mode = "global"
    92  			case *swarmapi.ServiceSpec_Replicated:
    93  				mode = "replicated"
    94  			case *swarmapi.ServiceSpec_ReplicatedJob:
    95  				mode = "replicated-job"
    96  			case *swarmapi.ServiceSpec_GlobalJob:
    97  				mode = "global-job"
    98  			}
    99  
   100  			if !options.Filters.ExactMatch("mode", mode) {
   101  				continue
   102  			}
   103  		}
   104  		if options.Status {
   105  			serviceIDs = append(serviceIDs, service.ID)
   106  		}
   107  		svcs, err := convert.ServiceFromGRPC(*service)
   108  		if err != nil {
   109  			return nil, err
   110  		}
   111  		services = append(services, svcs)
   112  	}
   113  
   114  	if options.Status {
   115  		// Listing service statuses is a separate call because, while it is the
   116  		// most common UI operation, it is still just a UI operation, and it
   117  		// would be improper to include this data in swarm's Service object.
   118  		// We pay the cost with some complexity here, but this is still way
   119  		// more efficient than marshalling and unmarshalling all the JSON
   120  		// needed to list tasks and get this data otherwise client-side
   121  		resp, err := state.controlClient.ListServiceStatuses(
   122  			ctx,
   123  			&swarmapi.ListServiceStatusesRequest{Services: serviceIDs},
   124  			grpc.MaxCallRecvMsgSize(defaultRecvSizeForListResponse),
   125  		)
   126  		if err != nil {
   127  			return nil, err
   128  		}
   129  
   130  		// we'll need to match up statuses in the response with the services in
   131  		// the list operation. if we did this by operating on two lists, the
   132  		// result would be quadratic. instead, make a mapping of service IDs to
   133  		// service statuses so that this is roughly linear. additionally,
   134  		// convert the status response to an engine api service status here.
   135  		serviceMap := map[string]*types.ServiceStatus{}
   136  		for _, status := range resp.Statuses {
   137  			serviceMap[status.ServiceID] = &types.ServiceStatus{
   138  				RunningTasks:   status.RunningTasks,
   139  				DesiredTasks:   status.DesiredTasks,
   140  				CompletedTasks: status.CompletedTasks,
   141  			}
   142  		}
   143  
   144  		// because this is a list of values and not pointers, make sure we
   145  		// actually alter the value when iterating.
   146  		for i, service := range services {
   147  			// the return value of the ListServiceStatuses operation is
   148  			// guaranteed to contain a value in the response for every argument
   149  			// in the request, so we can safely do this assignment. and even if
   150  			// it wasn't, and the service ID was for some reason absent from
   151  			// this map, the resulting value of service.Status would just be
   152  			// nil -- the same thing it was before
   153  			service.ServiceStatus = serviceMap[service.ID]
   154  			services[i] = service
   155  		}
   156  	}
   157  
   158  	return services, nil
   159  }
   160  
   161  // GetService returns a service based on an ID or name.
   162  func (c *Cluster) GetService(input string, insertDefaults bool) (types.Service, error) {
   163  	var service *swarmapi.Service
   164  	if err := c.lockedManagerAction(func(ctx context.Context, state nodeState) error {
   165  		s, err := getService(ctx, state.controlClient, input, insertDefaults)
   166  		if err != nil {
   167  			return err
   168  		}
   169  		service = s
   170  		return nil
   171  	}); err != nil {
   172  		return types.Service{}, err
   173  	}
   174  	svc, err := convert.ServiceFromGRPC(*service)
   175  	if err != nil {
   176  		return types.Service{}, err
   177  	}
   178  	return svc, nil
   179  }
   180  
   181  // CreateService creates a new service in a managed swarm cluster.
   182  func (c *Cluster) CreateService(s types.ServiceSpec, encodedAuth string, queryRegistry bool) (*apitypes.ServiceCreateResponse, error) {
   183  	var resp *apitypes.ServiceCreateResponse
   184  	err := c.lockedManagerAction(func(ctx context.Context, state nodeState) error {
   185  		err := c.populateNetworkID(ctx, state.controlClient, &s)
   186  		if err != nil {
   187  			return err
   188  		}
   189  
   190  		serviceSpec, err := convert.ServiceSpecToGRPC(s)
   191  		if err != nil {
   192  			return errdefs.InvalidParameter(err)
   193  		}
   194  
   195  		resp = &apitypes.ServiceCreateResponse{}
   196  
   197  		switch serviceSpec.Task.Runtime.(type) {
   198  		case *swarmapi.TaskSpec_Attachment:
   199  			return fmt.Errorf("invalid task spec: spec type %q not supported", types.RuntimeNetworkAttachment)
   200  		// handle other runtimes here
   201  		case *swarmapi.TaskSpec_Generic:
   202  			switch serviceSpec.Task.GetGeneric().Kind {
   203  			case string(types.RuntimePlugin):
   204  				if !c.config.Backend.HasExperimental() {
   205  					return fmt.Errorf("runtime type %q only supported in experimental", types.RuntimePlugin)
   206  				}
   207  				if s.TaskTemplate.PluginSpec == nil {
   208  					return errors.New("plugin spec must be set")
   209  				}
   210  
   211  			default:
   212  				return fmt.Errorf("unsupported runtime type: %q", serviceSpec.Task.GetGeneric().Kind)
   213  			}
   214  
   215  			r, err := state.controlClient.CreateService(ctx, &swarmapi.CreateServiceRequest{Spec: &serviceSpec})
   216  			if err != nil {
   217  				return err
   218  			}
   219  
   220  			resp.ID = r.Service.ID
   221  		case *swarmapi.TaskSpec_Container:
   222  			ctnr := serviceSpec.Task.GetContainer()
   223  			if ctnr == nil {
   224  				return errors.New("service does not use container tasks")
   225  			}
   226  			if encodedAuth != "" {
   227  				ctnr.PullOptions = &swarmapi.ContainerSpec_PullOptions{RegistryAuth: encodedAuth}
   228  			}
   229  
   230  			// retrieve auth config from encoded auth
   231  			authConfig := &apitypes.AuthConfig{}
   232  			if encodedAuth != "" {
   233  				authReader := strings.NewReader(encodedAuth)
   234  				dec := json.NewDecoder(base64.NewDecoder(base64.URLEncoding, authReader))
   235  				if err := dec.Decode(authConfig); err != nil {
   236  					logrus.Warnf("invalid authconfig: %v", err)
   237  				}
   238  			}
   239  
   240  			// pin image by digest for API versions < 1.30
   241  			// TODO(nishanttotla): The check on "DOCKER_SERVICE_PREFER_OFFLINE_IMAGE"
   242  			// should be removed in the future. Since integration tests only use the
   243  			// latest API version, so this is no longer required.
   244  			if os.Getenv("DOCKER_SERVICE_PREFER_OFFLINE_IMAGE") != "1" && queryRegistry {
   245  				digestImage, err := c.imageWithDigestString(ctx, ctnr.Image, authConfig)
   246  				if err != nil {
   247  					logrus.Warnf("unable to pin image %s to digest: %s", ctnr.Image, err.Error())
   248  					// warning in the client response should be concise
   249  					resp.Warnings = append(resp.Warnings, digestWarning(ctnr.Image))
   250  				} else if ctnr.Image != digestImage {
   251  					logrus.Debugf("pinning image %s by digest: %s", ctnr.Image, digestImage)
   252  					ctnr.Image = digestImage
   253  				} else {
   254  					logrus.Debugf("creating service using supplied digest reference %s", ctnr.Image)
   255  				}
   256  
   257  				// Replace the context with a fresh one.
   258  				// If we timed out while communicating with the
   259  				// registry, then "ctx" will already be expired, which
   260  				// would cause UpdateService below to fail. Reusing
   261  				// "ctx" could make it impossible to create a service
   262  				// if the registry is slow or unresponsive.
   263  				var cancel func()
   264  				ctx, cancel = c.getRequestContext()
   265  				defer cancel()
   266  			}
   267  
   268  			r, err := state.controlClient.CreateService(ctx, &swarmapi.CreateServiceRequest{Spec: &serviceSpec})
   269  			if err != nil {
   270  				return err
   271  			}
   272  
   273  			resp.ID = r.Service.ID
   274  		}
   275  		return nil
   276  	})
   277  
   278  	return resp, err
   279  }
   280  
   281  // UpdateService updates existing service to match new properties.
   282  func (c *Cluster) UpdateService(serviceIDOrName string, version uint64, spec types.ServiceSpec, flags apitypes.ServiceUpdateOptions, queryRegistry bool) (*apitypes.ServiceUpdateResponse, error) {
   283  	var resp *apitypes.ServiceUpdateResponse
   284  
   285  	err := c.lockedManagerAction(func(ctx context.Context, state nodeState) error {
   286  		err := c.populateNetworkID(ctx, state.controlClient, &spec)
   287  		if err != nil {
   288  			return err
   289  		}
   290  
   291  		serviceSpec, err := convert.ServiceSpecToGRPC(spec)
   292  		if err != nil {
   293  			return errdefs.InvalidParameter(err)
   294  		}
   295  
   296  		currentService, err := getService(ctx, state.controlClient, serviceIDOrName, false)
   297  		if err != nil {
   298  			return err
   299  		}
   300  
   301  		resp = &apitypes.ServiceUpdateResponse{}
   302  
   303  		switch serviceSpec.Task.Runtime.(type) {
   304  		case *swarmapi.TaskSpec_Attachment:
   305  			return fmt.Errorf("invalid task spec: spec type %q not supported", types.RuntimeNetworkAttachment)
   306  		case *swarmapi.TaskSpec_Generic:
   307  			switch serviceSpec.Task.GetGeneric().Kind {
   308  			case string(types.RuntimePlugin):
   309  				if spec.TaskTemplate.PluginSpec == nil {
   310  					return errors.New("plugin spec must be set")
   311  				}
   312  			}
   313  		case *swarmapi.TaskSpec_Container:
   314  			newCtnr := serviceSpec.Task.GetContainer()
   315  			if newCtnr == nil {
   316  				return errors.New("service does not use container tasks")
   317  			}
   318  
   319  			encodedAuth := flags.EncodedRegistryAuth
   320  			if encodedAuth != "" {
   321  				newCtnr.PullOptions = &swarmapi.ContainerSpec_PullOptions{RegistryAuth: encodedAuth}
   322  			} else {
   323  				// this is needed because if the encodedAuth isn't being updated then we
   324  				// shouldn't lose it, and continue to use the one that was already present
   325  				var ctnr *swarmapi.ContainerSpec
   326  				switch flags.RegistryAuthFrom {
   327  				case apitypes.RegistryAuthFromSpec, "":
   328  					ctnr = currentService.Spec.Task.GetContainer()
   329  				case apitypes.RegistryAuthFromPreviousSpec:
   330  					if currentService.PreviousSpec == nil {
   331  						return errors.New("service does not have a previous spec")
   332  					}
   333  					ctnr = currentService.PreviousSpec.Task.GetContainer()
   334  				default:
   335  					return errors.New("unsupported registryAuthFrom value")
   336  				}
   337  				if ctnr == nil {
   338  					return errors.New("service does not use container tasks")
   339  				}
   340  				newCtnr.PullOptions = ctnr.PullOptions
   341  				// update encodedAuth so it can be used to pin image by digest
   342  				if ctnr.PullOptions != nil {
   343  					encodedAuth = ctnr.PullOptions.RegistryAuth
   344  				}
   345  			}
   346  
   347  			// retrieve auth config from encoded auth
   348  			authConfig := &apitypes.AuthConfig{}
   349  			if encodedAuth != "" {
   350  				if err := json.NewDecoder(base64.NewDecoder(base64.URLEncoding, strings.NewReader(encodedAuth))).Decode(authConfig); err != nil {
   351  					logrus.Warnf("invalid authconfig: %v", err)
   352  				}
   353  			}
   354  
   355  			// pin image by digest for API versions < 1.30
   356  			// TODO(nishanttotla): The check on "DOCKER_SERVICE_PREFER_OFFLINE_IMAGE"
   357  			// should be removed in the future. Since integration tests only use the
   358  			// latest API version, so this is no longer required.
   359  			if os.Getenv("DOCKER_SERVICE_PREFER_OFFLINE_IMAGE") != "1" && queryRegistry {
   360  				digestImage, err := c.imageWithDigestString(ctx, newCtnr.Image, authConfig)
   361  				if err != nil {
   362  					logrus.Warnf("unable to pin image %s to digest: %s", newCtnr.Image, err.Error())
   363  					// warning in the client response should be concise
   364  					resp.Warnings = append(resp.Warnings, digestWarning(newCtnr.Image))
   365  				} else if newCtnr.Image != digestImage {
   366  					logrus.Debugf("pinning image %s by digest: %s", newCtnr.Image, digestImage)
   367  					newCtnr.Image = digestImage
   368  				} else {
   369  					logrus.Debugf("updating service using supplied digest reference %s", newCtnr.Image)
   370  				}
   371  
   372  				// Replace the context with a fresh one.
   373  				// If we timed out while communicating with the
   374  				// registry, then "ctx" will already be expired, which
   375  				// would cause UpdateService below to fail. Reusing
   376  				// "ctx" could make it impossible to update a service
   377  				// if the registry is slow or unresponsive.
   378  				var cancel func()
   379  				ctx, cancel = c.getRequestContext()
   380  				defer cancel()
   381  			}
   382  		}
   383  
   384  		var rollback swarmapi.UpdateServiceRequest_Rollback
   385  		switch flags.Rollback {
   386  		case "", "none":
   387  			rollback = swarmapi.UpdateServiceRequest_NONE
   388  		case "previous":
   389  			rollback = swarmapi.UpdateServiceRequest_PREVIOUS
   390  		default:
   391  			return fmt.Errorf("unrecognized rollback option %s", flags.Rollback)
   392  		}
   393  
   394  		_, err = state.controlClient.UpdateService(
   395  			ctx,
   396  			&swarmapi.UpdateServiceRequest{
   397  				ServiceID: currentService.ID,
   398  				Spec:      &serviceSpec,
   399  				ServiceVersion: &swarmapi.Version{
   400  					Index: version,
   401  				},
   402  				Rollback: rollback,
   403  			},
   404  		)
   405  		return err
   406  	})
   407  	return resp, err
   408  }
   409  
   410  // RemoveService removes a service from a managed swarm cluster.
   411  func (c *Cluster) RemoveService(input string) error {
   412  	return c.lockedManagerAction(func(ctx context.Context, state nodeState) error {
   413  		service, err := getService(ctx, state.controlClient, input, false)
   414  		if err != nil {
   415  			return err
   416  		}
   417  
   418  		_, err = state.controlClient.RemoveService(ctx, &swarmapi.RemoveServiceRequest{ServiceID: service.ID})
   419  		return err
   420  	})
   421  }
   422  
   423  // ServiceLogs collects service logs and writes them back to `config.OutStream`
   424  func (c *Cluster) ServiceLogs(ctx context.Context, selector *backend.LogSelector, config *apitypes.ContainerLogsOptions) (<-chan *backend.LogMessage, error) {
   425  	c.mu.RLock()
   426  	defer c.mu.RUnlock()
   427  
   428  	state := c.currentNodeState()
   429  	if !state.IsActiveManager() {
   430  		return nil, c.errNoManager(state)
   431  	}
   432  
   433  	swarmSelector, err := convertSelector(ctx, state.controlClient, selector)
   434  	if err != nil {
   435  		return nil, errors.Wrap(err, "error making log selector")
   436  	}
   437  
   438  	// set the streams we'll use
   439  	stdStreams := []swarmapi.LogStream{}
   440  	if config.ShowStdout {
   441  		stdStreams = append(stdStreams, swarmapi.LogStreamStdout)
   442  	}
   443  	if config.ShowStderr {
   444  		stdStreams = append(stdStreams, swarmapi.LogStreamStderr)
   445  	}
   446  
   447  	// Get tail value squared away - the number of previous log lines we look at
   448  	var tail int64
   449  	// in ContainerLogs, if the tail value is ANYTHING non-integer, we just set
   450  	// it to -1 (all). i don't agree with that, but i also think no tail value
   451  	// should be legitimate. if you don't pass tail, we assume you want "all"
   452  	if config.Tail == "all" || config.Tail == "" {
   453  		// tail of 0 means send all logs on the swarmkit side
   454  		tail = 0
   455  	} else {
   456  		t, err := strconv.Atoi(config.Tail)
   457  		if err != nil {
   458  			return nil, errors.New("tail value must be a positive integer or \"all\"")
   459  		}
   460  		if t < 0 {
   461  			return nil, errors.New("negative tail values not supported")
   462  		}
   463  		// we actually use negative tail in swarmkit to represent messages
   464  		// backwards starting from the beginning. also, -1 means no logs. so,
   465  		// basically, for api compat with docker container logs, add one and
   466  		// flip the sign. we error above if you try to negative tail, which
   467  		// isn't supported by docker (and would error deeper in the stack
   468  		// anyway)
   469  		//
   470  		// See the logs protobuf for more information
   471  		tail = int64(-(t + 1))
   472  	}
   473  
   474  	// get the since value - the time in the past we're looking at logs starting from
   475  	var sinceProto *gogotypes.Timestamp
   476  	if config.Since != "" {
   477  		s, n, err := timetypes.ParseTimestamps(config.Since, 0)
   478  		if err != nil {
   479  			return nil, errors.Wrap(err, "could not parse since timestamp")
   480  		}
   481  		since := time.Unix(s, n)
   482  		sinceProto, err = gogotypes.TimestampProto(since)
   483  		if err != nil {
   484  			return nil, errors.Wrap(err, "could not parse timestamp to proto")
   485  		}
   486  	}
   487  
   488  	stream, err := state.logsClient.SubscribeLogs(ctx, &swarmapi.SubscribeLogsRequest{
   489  		Selector: swarmSelector,
   490  		Options: &swarmapi.LogSubscriptionOptions{
   491  			Follow:  config.Follow,
   492  			Streams: stdStreams,
   493  			Tail:    tail,
   494  			Since:   sinceProto,
   495  		},
   496  	})
   497  	if err != nil {
   498  		return nil, err
   499  	}
   500  
   501  	messageChan := make(chan *backend.LogMessage, 1)
   502  	go func() {
   503  		defer close(messageChan)
   504  		for {
   505  			// Check the context before doing anything.
   506  			select {
   507  			case <-ctx.Done():
   508  				return
   509  			default:
   510  			}
   511  			subscribeMsg, err := stream.Recv()
   512  			if err == io.EOF {
   513  				return
   514  			}
   515  			// if we're not io.EOF, push the message in and return
   516  			if err != nil {
   517  				select {
   518  				case <-ctx.Done():
   519  				case messageChan <- &backend.LogMessage{Err: err}:
   520  				}
   521  				return
   522  			}
   523  
   524  			for _, msg := range subscribeMsg.Messages {
   525  				// make a new message
   526  				m := new(backend.LogMessage)
   527  				m.Attrs = make([]backend.LogAttr, 0, len(msg.Attrs)+3)
   528  				// add the timestamp, adding the error if it fails
   529  				m.Timestamp, err = gogotypes.TimestampFromProto(msg.Timestamp)
   530  				if err != nil {
   531  					m.Err = err
   532  				}
   533  
   534  				nodeKey := contextPrefix + ".node.id"
   535  				serviceKey := contextPrefix + ".service.id"
   536  				taskKey := contextPrefix + ".task.id"
   537  
   538  				// copy over all of the details
   539  				for _, d := range msg.Attrs {
   540  					switch d.Key {
   541  					case nodeKey, serviceKey, taskKey:
   542  						// we have the final say over context details (in case there
   543  						// is a conflict (if the user added a detail with a context's
   544  						// key for some reason))
   545  					default:
   546  						m.Attrs = append(m.Attrs, backend.LogAttr{Key: d.Key, Value: d.Value})
   547  					}
   548  				}
   549  				m.Attrs = append(m.Attrs,
   550  					backend.LogAttr{Key: nodeKey, Value: msg.Context.NodeID},
   551  					backend.LogAttr{Key: serviceKey, Value: msg.Context.ServiceID},
   552  					backend.LogAttr{Key: taskKey, Value: msg.Context.TaskID},
   553  				)
   554  
   555  				switch msg.Stream {
   556  				case swarmapi.LogStreamStdout:
   557  					m.Source = "stdout"
   558  				case swarmapi.LogStreamStderr:
   559  					m.Source = "stderr"
   560  				}
   561  				m.Line = msg.Data
   562  
   563  				// there could be a case where the reader stops accepting
   564  				// messages and the context is canceled. we need to check that
   565  				// here, or otherwise we risk blocking forever on the message
   566  				// send.
   567  				select {
   568  				case <-ctx.Done():
   569  					return
   570  				case messageChan <- m:
   571  				}
   572  			}
   573  		}
   574  	}()
   575  	return messageChan, nil
   576  }
   577  
   578  // convertSelector takes a backend.LogSelector, which contains raw names that
   579  // may or may not be valid, and converts them to an api.LogSelector proto. It
   580  // returns an error if something fails
   581  func convertSelector(ctx context.Context, cc swarmapi.ControlClient, selector *backend.LogSelector) (*swarmapi.LogSelector, error) {
   582  	// don't rely on swarmkit to resolve IDs, do it ourselves
   583  	swarmSelector := &swarmapi.LogSelector{}
   584  	for _, s := range selector.Services {
   585  		service, err := getService(ctx, cc, s, false)
   586  		if err != nil {
   587  			return nil, err
   588  		}
   589  		c := service.Spec.Task.GetContainer()
   590  		if c == nil {
   591  			return nil, errors.New("logs only supported on container tasks")
   592  		}
   593  		swarmSelector.ServiceIDs = append(swarmSelector.ServiceIDs, service.ID)
   594  	}
   595  	for _, t := range selector.Tasks {
   596  		task, err := getTask(ctx, cc, t)
   597  		if err != nil {
   598  			return nil, err
   599  		}
   600  		c := task.Spec.GetContainer()
   601  		if c == nil {
   602  			return nil, errors.New("logs only supported on container tasks")
   603  		}
   604  		swarmSelector.TaskIDs = append(swarmSelector.TaskIDs, task.ID)
   605  	}
   606  	return swarmSelector, nil
   607  }
   608  
   609  // imageWithDigestString takes an image such as name or name:tag
   610  // and returns the image pinned to a digest, such as name@sha256:34234
   611  func (c *Cluster) imageWithDigestString(ctx context.Context, image string, authConfig *apitypes.AuthConfig) (string, error) {
   612  	ref, err := reference.ParseAnyReference(image)
   613  	if err != nil {
   614  		return "", err
   615  	}
   616  	namedRef, ok := ref.(reference.Named)
   617  	if !ok {
   618  		if _, ok := ref.(reference.Digested); ok {
   619  			return image, nil
   620  		}
   621  		return "", errors.Errorf("unknown image reference format: %s", image)
   622  	}
   623  	// only query registry if not a canonical reference (i.e. with digest)
   624  	if _, ok := namedRef.(reference.Canonical); !ok {
   625  		namedRef = reference.TagNameOnly(namedRef)
   626  
   627  		taggedRef, ok := namedRef.(reference.NamedTagged)
   628  		if !ok {
   629  			return "", errors.Errorf("image reference not tagged: %s", image)
   630  		}
   631  
   632  		repo, err := c.config.ImageBackend.GetRepository(ctx, taggedRef, authConfig)
   633  		if err != nil {
   634  			return "", err
   635  		}
   636  		dscrptr, err := repo.Tags(ctx).Get(ctx, taggedRef.Tag())
   637  		if err != nil {
   638  			return "", err
   639  		}
   640  
   641  		namedDigestedRef, err := reference.WithDigest(taggedRef, dscrptr.Digest)
   642  		if err != nil {
   643  			return "", err
   644  		}
   645  		// return familiar form until interface updated to return type
   646  		return reference.FamiliarString(namedDigestedRef), nil
   647  	}
   648  	// reference already contains a digest, so just return it
   649  	return reference.FamiliarString(ref), nil
   650  }
   651  
   652  // digestWarning constructs a formatted warning string
   653  // using the image name that could not be pinned by digest. The
   654  // formatting is hardcoded, but could me made smarter in the future
   655  func digestWarning(image string) string {
   656  	return fmt.Sprintf("image %s could not be accessed on a registry to record\nits digest. Each node will access %s independently,\npossibly leading to different nodes running different\nversions of the image.\n", image, image)
   657  }