lttng-relayd(8)

1LTTNG-RELAYD(8)                  LTTng Manual                  LTTNG-RELAYD(8)
2
3
4

NAME

6       lttng-relayd - LTTng 2 relay daemon
7

SYNOPSIS

9       lttng-relayd [--background | --daemonize] [--config=PATH]
10                    [--control-port=URL] [--data-port=URL] [--fd-pool-size=COUNT]
11                    [--live-port=URL] [--output=PATH]
12                    [-v | -vv | -vvv] [--working-directory=PATH]
13                    [--group-output-by-session] [--disallow-clear]
14

DESCRIPTION

16       The Linux Trace Toolkit: next generation <https://lttng.org/> is an
17       open source software package used for correlated tracing of the Linux
18       kernel, user applications, and user libraries.
19
20       LTTng consists of Linux kernel modules (for Linux kernel tracing) and
21       dynamically loaded libraries (for user application and library
22       tracing).
23
24       The LTTng relay daemon is responsible for receiving trace data from
25       possibly remote LTTng session/consumer daemons and for writing it to
26       the local file system. The relay daemon also accepts LTTng live
27       connections from compatible viewers; this is the official approach to
28       viewing LTTng events as they are emitted.
29
30       The relay daemon listens by default on all network interfaces to gather
31       trace data, but only on localhost for LTTng live connections.
32
33       The relay daemon does not require any particular permissions, as long
34       as it can write to the output directory and listen on the configured
35       ports. If a user is within a secured network and/or has proper firewall
36       settings, lttng-relayd can listen to LTTng live connections from all
37       network interfaces by specifying --live-port=tcp://0.0.0.0:5344.
38
39       Once a trace has been streamed completely, the trace can be processed
40       by any tool that can process an LTTng trace located on the local file
41       system.
42
43   Output directory
44       The relay daemon uses different output path patterns depending on:
45
46       •   Its configuration.
47
48       •   The connected peer’s tracing session configuration.
49
50       •   The connected peer’s LTTng session daemon (see lttng-sessiond(8))
51           version.
52
53       Consider the following variables:
54
55       BASE
56           Base output directory: $LTTNG_HOME/lttng-traces or the argument of
57           the --output option.
58
59               Note
60               $LTTNG_HOME defaults to $HOME when not explicitly set.
61
62       HOSTNAME
63           Peer’s hostname.
64
65       SESSION
66           Tracing session name.
67
68       DATETIME
69           Unique tracing session date/time.
70
71       TRACEPATH
72           Custom trace path (TRACEPATH part of the lttng-create(1) command’s
73           --set-url option’s argument, if any).
74
75       The relay daemon output path patterns are:
76
77       Hostname grouping (without --group-output-by-session)
78
79           Without a custom trace path
80
81                   BASE/HOSTNAME/SESSION-DATETIME
82
83           With a custom trace path
84
85                   BASE/HOSTNAME/TRACEPATH
86
87       Tracing session grouping (with --group-output-by-session)
88
89           Without a custom trace path
90
91               The peer’s LTTng session daemon version is at least 2.4
92
93                       BASE/SESSION/HOSTNAME-DATETIME
94
95               Otherwise
96                   Defaults to the hostname grouping pattern:
97
98                       BASE/HOSTNAME/SESSION-DATETIME
99
100           With a custom trace path
101
102               The peer’s LTTng session daemon version is at least 2.4
103
104                       BASE/SESSION/HOSTNAME-DATETIME/TRACEPATH
105
106               Otherwise
107                   Defaults to the hostname grouping pattern:
108
109                       BASE/HOSTNAME/TRACEPATH
110
111   URL format
112       The --control-port, --data-port, and --live-port options specify URLs.
113
114       The format of those URLs is:
115
116           tcp://(HOST | IPADDR):PORT
117
118       with:
119
120       (HOST | IPADDR)
121           Binding hostname or IP address (IPv6 address must be enclosed in
122           brackets ([ and ]); see RFC 2732
123           <https://www.ietf.org/rfc/rfc2732.txt>).
124
125       PORT
126           TCP port.
127

OPTIONS

129   Daemon
130       -b, --background
131           Start as Unix daemon, but keep file descriptors (console) open. Use
132           the --daemonize option instead to close the file descriptors.
133
134       -f PATH, --config=PATH
135           Load relay daemon configuration from path PATH.
136
137       -d, --daemonize
138           Start as Unix daemon, and close file descriptors (console). Use the
139           --background option instead to keep the file descriptors open.
140
141       -x, --disallow-clear
142           Disallow clearing operations (see lttng-clear(1)).
143
144           See also the LTTNG_RELAYD_DISALLOW_CLEAR environment variable.
145
146       --fd-pool-size=SIZE
147           Set the size of the file descriptor pool to SIZE.
148
149           SIZE is the maximum number of file descriptors that may be kept
150           opened simultaneously by the relay daemon.
151
152           Default: the soft RLIMIT_NOFILE resource limit of the process (see
153           getrlimit(2)).
154
155       -g GROUP, --group=GROUP
156           Use GROUP as Unix tracing group (default: tracing).
157
158       -w PATH, --working-directory=PATH
159           Set the working directory of the processes the relay daemon creates
160           to PATH.
161
162           See also the LTTNG_RELAYD_WORKING_DIRECTORY environment variable.
163
164       -v, --verbose
165           Increase verbosity.
166
167           Three levels of verbosity are available, which are triggered by
168           appending additional v letters to the option (that is, -vv and
169           -vvv).
170
171   Output
172       See the Output directory section above for more information.
173
174       -p, --group-output-by-host
175           Group the written trace directories by hostname (default).
176
177       -s, --group-output-by-session
178           Group the written trace directories by tracing session name instead
179           of by hostname.
180
181       -o PATH, --output=PATH
182           Set the base output directory of the written trace directories to
183           PATH.
184
185   Ports
186       See the URL format section above for more information about the syntax
187       of the following URL argument.
188
189       -C URL, --control-port=URL
190           Listen to control data on URL URL (default: tcp://0.0.0.0:5342).
191
192       -D URL, --data-port=URL
193           Listen to trace data on URL URL (default: tcp://0.0.0.0:5343).
194
195       -L URL, --live-port=URL
196           Listen to LTTng live connections on URL URL (default:
197           tcp://localhost:5344).
198
199   Program information
200       -h, --help
201           Show help.
202
203       -V, --version
204           Show version.
205

ENVIRONMENT VARIABLES

207       LTTNG_ABORT_ON_ERROR
208           Set to 1 to abort the process after the first error is encountered.
209
210       LTTNG_NETWORK_SOCKET_TIMEOUT
211           Socket connection, receive and send timeout (milliseconds). A value
212           of 0 or -1 uses the timeout of the operating system (default).
213
214       LTTNG_RELAYD_DISALLOW_CLEAR
215           Set to 1 to disallow clearing operations (see lttng-clear(1)).
216
217           The --disallow-clear option overrides this variable.
218
219       LTTNG_RELAYD_HEALTH
220           Path to relay daemon health’s socket.
221
222       LTTNG_RELAYD_TCP_KEEP_ALIVE
223           Set to 1 to enable TCP keep-alive.
224
225           The TCP keep-alive mechanism allows the detection of dead peers
226           (lttng-sessiond(8)) in cases of unclean termination (for example, a
227           hard reset) of a peer.
228
229           Supported on Linux and Solaris only. The default behaviour of the
230           TCP keep-alive mechanism is OS-specific.
231
232           Search for tcp_keepalive in tcp(7) for more information.
233
234       LTTNG_RELAYD_TCP_KEEP_ALIVE_ABORT_THRESHOLD
235           The time threshold in seconds to abort a TCP connection after the
236           keep-alive probing mechanism has failed.
237
238           Set to 0 or -1 to use the value chosen by the operating system
239           (default).
240
241           Supported on Solaris 11 only.
242
243           Search for tcp_keepalive_abort_threshold in tcp(7) for more
244           information.
245
246       LTTNG_RELAYD_TCP_KEEP_ALIVE_IDLE_TIME
247           Number of seconds a connection needs to be idle before TCP begins
248           sending out keep-alive probes.
249
250           Set to 0 or -1 to use the value chosen by the operating system
251           (default).
252
253           Supported on Linux and Solaris 11 only.
254
255           On Solaris 11, the accepted values are -1, 0, and 10 to 864000.
256
257           Search for tcp_keepalive_time and tcp_keepalive_interval in tcp(7)
258           on Solaris 11 for more information.
259
260       LTTNG_RELAYD_TCP_KEEP_ALIVE_MAX_PROBE_COUNT
261           Maximum number of TCP keep-alive probes to send before giving up
262           and killing the connection if no response is obtained from the
263           other end.
264
265           Set to 0 or -1 to use the value chosen by the operating system
266           (default).
267
268           Supported on Linux only.
269
270           Search for tcp_keepalive_probes in tcp(7) for more information.
271
272       LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBE_INTERVAL
273           Number of seconds between TCP keep-alive probes.
274
275           Set to 0 or -1 to use the value chosen by the operating system
276           (default).
277
278           Supported on Linux only.
279
280           Search for tcp_keepalive_intvl in tcp(7) for more information.
281
282       LTTNG_RELAYD_WORKING_DIRECTORY
283           Working directory of the processes the relay daemon creates.
284
285           The --working-directory option overrides this variable.
286

FILES

288       $LTTNG_HOME/.lttng
289           User LTTng runtime and configuration directory.
290
291       $LTTNG_HOME/lttng-traces
292           Default base output directory of LTTng traces. This can be
293           overridden with the --output option.
294
295           Note
296           $LTTNG_HOME defaults to $HOME when not explicitly set.
297

EXIT STATUS

299       0
300           Success
301
302       1
303           Error
304
305       3
306           Fatal error
307

LIMITATIONS

309       As of this version, only the TCP protocol is supported for both control
310       and data ports. In future versions, TCP will remain the sole available
311       protocol for control data since those communications are low-volume and
312       need absolute reliability; trace data could be carried over UDP.
313
314       For an unprivileged user running lttng-relayd, the maximum number of
315       file descriptors per process is usually 1024. This limits the number of
316       connections and opened trace files. This limit can be configured with
317       ulimit(3).
318

BUGS

320       If you encounter any issue or usability problem, please report it on
321       the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.
322

RESOURCES

324       •   LTTng project website <https://lttng.org>
325
326       •   LTTng documentation <https://lttng.org/docs>
327
328       •   Git repositories <http://git.lttng.org>
329
330       •   GitHub organization <http://github.com/lttng>
331
332       •   Continuous integration <http://ci.lttng.org/>
333
334       •   Mailing list <http://lists.lttng.org> for support and development:
335           lttng-dev@lists.lttng.org
336
337       •   IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
338

COPYRIGHTS

340       This program is part of the LTTng-tools project.
341
342       LTTng-tools is distributed under the GNU General Public License version
343       2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the
344       LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file
345       for details.
346

THANKS

348       Special thanks to Michel Dagenais and the DORSAL laboratory
349       <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for
350       the LTTng journey.
351
352       Also thanks to the Ericsson teams working on tracing which helped us
353       greatly with detailed bug reports and unusual test cases.
354