github.com/kunnos/engine@v1.13.1/daemon/logger/journald/journald.go (about)

     1  // +build linux
     2  
     3  // Package journald provides the log driver for forwarding server logs
     4  // to endpoints that receive the systemd format.
     5  package journald
     6  
     7  import (
     8  	"fmt"
     9  	"sync"
    10  	"unicode"
    11  
    12  	"github.com/sirupsen/logrus"
    13  	"github.com/coreos/go-systemd/journal"
    14  	"github.com/docker/docker/daemon/logger"
    15  	"github.com/docker/docker/daemon/logger/loggerutils"
    16  )
    17  
    18  const name = "journald"
    19  
    20  type journald struct {
    21  	vars    map[string]string // additional variables and values to send to the journal along with the log message
    22  	readers readerList
    23  }
    24  
    25  type readerList struct {
    26  	mu      sync.Mutex
    27  	readers map[*logger.LogWatcher]*logger.LogWatcher
    28  }
    29  
    30  func init() {
    31  	if err := logger.RegisterLogDriver(name, New); err != nil {
    32  		logrus.Fatal(err)
    33  	}
    34  	if err := logger.RegisterLogOptValidator(name, validateLogOpt); err != nil {
    35  		logrus.Fatal(err)
    36  	}
    37  }
    38  
    39  // sanitizeKeyMode returns the sanitized string so that it could be used in journald.
    40  // In journald log, there are special requirements for fields.
    41  // Fields must be composed of uppercase letters, numbers, and underscores, but must
    42  // not start with an underscore.
    43  func sanitizeKeyMod(s string) string {
    44  	n := ""
    45  	for _, v := range s {
    46  		if 'a' <= v && v <= 'z' {
    47  			v = unicode.ToUpper(v)
    48  		} else if ('Z' < v || v < 'A') && ('9' < v || v < '0') {
    49  			v = '_'
    50  		}
    51  		// If (n == "" && v == '_'), then we will skip as this is the beginning with '_'
    52  		if !(n == "" && v == '_') {
    53  			n += string(v)
    54  		}
    55  	}
    56  	return n
    57  }
    58  
    59  // New creates a journald logger using the configuration passed in on
    60  // the context.
    61  func New(ctx logger.Context) (logger.Logger, error) {
    62  	if !journal.Enabled() {
    63  		return nil, fmt.Errorf("journald is not enabled on this host")
    64  	}
    65  	// Strip a leading slash so that people can search for
    66  	// CONTAINER_NAME=foo rather than CONTAINER_NAME=/foo.
    67  	name := ctx.ContainerName
    68  	if name[0] == '/' {
    69  		name = name[1:]
    70  	}
    71  
    72  	// parse log tag
    73  	tag, err := loggerutils.ParseLogTag(ctx, loggerutils.DefaultTemplate)
    74  	if err != nil {
    75  		return nil, err
    76  	}
    77  
    78  	vars := map[string]string{
    79  		"CONTAINER_ID":      ctx.ContainerID[:12],
    80  		"CONTAINER_ID_FULL": ctx.ContainerID,
    81  		"CONTAINER_NAME":    name,
    82  		"CONTAINER_TAG":     tag,
    83  	}
    84  	extraAttrs := ctx.ExtraAttributes(sanitizeKeyMod)
    85  	for k, v := range extraAttrs {
    86  		vars[k] = v
    87  	}
    88  	return &journald{vars: vars, readers: readerList{readers: make(map[*logger.LogWatcher]*logger.LogWatcher)}}, nil
    89  }
    90  
    91  // We don't actually accept any options, but we have to supply a callback for
    92  // the factory to pass the (probably empty) configuration map to.
    93  func validateLogOpt(cfg map[string]string) error {
    94  	for key := range cfg {
    95  		switch key {
    96  		case "labels":
    97  		case "env":
    98  		case "tag":
    99  		default:
   100  			return fmt.Errorf("unknown log opt '%s' for journald log driver", key)
   101  		}
   102  	}
   103  	return nil
   104  }
   105  
   106  func (s *journald) Log(msg *logger.Message) error {
   107  	vars := map[string]string{}
   108  	for k, v := range s.vars {
   109  		vars[k] = v
   110  	}
   111  	if msg.Partial {
   112  		vars["CONTAINER_PARTIAL_MESSAGE"] = "true"
   113  	}
   114  	if msg.Source == "stderr" {
   115  		return journal.Send(string(msg.Line), journal.PriErr, vars)
   116  	}
   117  	return journal.Send(string(msg.Line), journal.PriInfo, vars)
   118  }
   119  
   120  func (s *journald) Name() string {
   121  	return name
   122  }