dotcloud/docker

package gcplogs // import "github.com/docker/docker/daemon/logger/gcplogs"

import (
    "context"
    "fmt"
    "sync"
    "sync/atomic"
    "time"

    "github.com/docker/docker/daemon/logger"

    "cloud.google.com/go/compute/metadata"
    "cloud.google.com/go/logging"
    "github.com/containerd/log"
    mrpb "google.golang.org/genproto/googleapis/api/monitoredres"
)

const (
    name = "gcplogs"

    projectOptKey     = "gcp-project"
    logLabelsKey      = "labels"
    logLabelsRegexKey = "labels-regex"
    logEnvKey         = "env"
    logEnvRegexKey    = "env-regex"
    logCmdKey         = "gcp-log-cmd"
    logZoneKey        = "gcp-meta-zone"
    logNameKey        = "gcp-meta-name"
    logIDKey          = "gcp-meta-id"
)

var (
    // The number of logs the gcplogs driver has dropped.
    droppedLogs uint64

    onGCE bool

    // instance metadata populated from the metadata server if available
    projectID    string
    zone         string
    instanceName string
    instanceID   string
)

func init() {
    if err := logger.RegisterLogDriver(name, New); err != nil {
        panic(err)
    }

    if err := logger.RegisterLogOptValidator(name, ValidateLogOpts); err != nil {
        panic(err)
    }
}

type gcplogs struct {
    client    *logging.Client
    logger    *logging.Logger
    instance  *instanceInfo
    container *containerInfo
}

type dockerLogEntry struct {
    Instance  *instanceInfo  `json:"instance,omitempty"`
    Container *containerInfo `json:"container,omitempty"`
    Message   string         `json:"message,omitempty"`
}

type instanceInfo struct {
    Zone string `json:"zone,omitempty"`
    Name string `json:"name,omitempty"`
    ID   string `json:"id,omitempty"`
}

type containerInfo struct {
    Name      string            `json:"name,omitempty"`
    ID        string            `json:"id,omitempty"`
    ImageName string            `json:"imageName,omitempty"`
    ImageID   string            `json:"imageId,omitempty"`
    Created   time.Time         `json:"created,omitempty"`
    Command   string            `json:"command,omitempty"`
    Metadata  map[string]string `json:"metadata,omitempty"`
}

var initGCPOnce sync.Once

func initGCP() {
    initGCPOnce.Do(func() {
        onGCE = metadata.OnGCE()
        if onGCE {
            // These will fail on instances if the metadata service is
            // down or the client is compiled with an API version that
            // has been removed. Since these are not vital, let's ignore
            // them and make their fields in the dockerLogEntry ,omitempty
            projectID, _ = metadata.ProjectID()
            zone, _ = metadata.Zone()
            instanceName, _ = metadata.InstanceName()
            instanceID, _ = metadata.InstanceID()
        }
    })
}

// New creates a new logger that logs to Google Cloud Logging using the application
// default credentials.
//
// See https://developers.google.com/identity/protocols/application-default-credentials
func New(info logger.Info) (logger.Logger, error) {
    initGCP()

    var project string
    if projectID != "" {
        project = projectID
    }
    if projectID, found := info.Config[projectOptKey]; found {
        project = projectID
    }
    if project == "" {
        return nil, fmt.Errorf("No project was specified and couldn't read project from the metadata server. Please specify a project")
    }

    c, err := logging.NewClient(context.Background(), project)
    if err != nil {
        return nil, err
    }
    var instanceResource *instanceInfo
    if onGCE {
        instanceResource = &instanceInfo{
            Zone: zone,
            Name: instanceName,
            ID:   instanceID,
        }
    } else if info.Config[logZoneKey] != "" || info.Config[logNameKey] != "" || info.Config[logIDKey] != "" {
        instanceResource = &instanceInfo{
            Zone: info.Config[logZoneKey],
            Name: info.Config[logNameKey],
            ID:   info.Config[logIDKey],
        }
    }

    options := []logging.LoggerOption{}
    if instanceResource != nil {
        vmMrpb := logging.CommonResource(
            &mrpb.MonitoredResource{
                Type: "gce_instance",
                Labels: map[string]string{
                    "instance_id": instanceResource.ID,
                    "zone":        instanceResource.Zone,
                },
            },
        )
        options = []logging.LoggerOption{vmMrpb}
    }
    lg := c.Logger("gcplogs-docker-driver", options...)

    if err := c.Ping(context.Background()); err != nil {
        return nil, fmt.Errorf("unable to connect or authenticate with Google Cloud Logging: %v", err)
    }

    extraAttributes, err := info.ExtraAttributes(nil)
    if err != nil {
        return nil, err
    }

    l := &gcplogs{
        client: c,
        logger: lg,
        container: &containerInfo{
            Name:      info.ContainerName,
            ID:        info.ContainerID,
            ImageName: info.ContainerImageName,
            ImageID:   info.ContainerImageID,
            Created:   info.ContainerCreated,
            Metadata:  extraAttributes,
        },
    }

    if info.Config[logCmdKey] == "true" {
        l.container.Command = info.Command()
    }

    if instanceResource != nil {
        l.instance = instanceResource
    }

    // The logger "overflows" at a rate of 10,000 logs per second and this
    // overflow func is called. We want to surface the error to the user
    // without overly spamming /var/log/docker.log so we log the first time
    // we overflow and every 1000th time after.
    c.OnError = func(err error) {
        if err == logging.ErrOverflow {
            if i := atomic.AddUint64(&droppedLogs, 1); i%1000 == 1 {
                log.G(context.TODO()).Errorf("gcplogs driver has dropped %v logs", i)
            }
        } else {
            log.G(context.TODO()).Error(err)
        }
    }

    return l, nil
}

// ValidateLogOpts validates the opts passed to the gcplogs driver. Currently, the gcplogs
// driver doesn't take any arguments.
func ValidateLogOpts(cfg map[string]string) error {
    for k := range cfg {
        switch k {
        case projectOptKey, logLabelsKey, logLabelsRegexKey, logEnvKey, logEnvRegexKey, logCmdKey, logZoneKey, logNameKey, logIDKey:
        default:
            return fmt.Errorf("%q is not a valid option for the gcplogs driver", k)
        }
    }
    return nil
}

func (l *gcplogs) Log(m *logger.Message) error {
    message := string(m.Line)
    ts := m.Timestamp
    logger.PutMessage(m)

    l.logger.Log(logging.Entry{
        Timestamp: ts,
        Payload: &dockerLogEntry{
            Instance:  l.instance,
            Container: l.container,
            Message:   message,
        },
    })
    return nil
}

func (l *gcplogs) Close() error {
    l.logger.Flush()
    return l.client.Close()
}

func (l *gcplogs) Name() string {
    return name
}