8 lttng-relayd - LTTng 2 relay daemon
14 *lttng-relayd* [option:--background | option:--daemonize]
15 [option:--control-port='URL'] [option:--data-port='URL'] [option:--fd-pool-size='COUNT']
16 [option:--live-port='URL'] [option:--output='PATH']
17 [option:-v | option:-vv | option:-vvv] [option:--working-directory='PATH']
18 [option:--group-output-by-session] [option:--disallow-clear]
23 The https://lttng.org/[_Linux Trace Toolkit: next generation_] is an open
24 source software package used for correlated tracing of the Linux kernel,
25 user applications, and user libraries.
27 LTTng consists of Linux kernel modules (for Linux kernel tracing) and
28 dynamically loaded libraries (for user application and library tracing).
30 The _LTTng relay daemon_ is responsible for receiving trace data from
31 possibly remote LTTng session/consumer daemons and for writing it to
32 the local file system. The relay daemon also accepts _LTTng live_
33 connections from compatible viewers; this is the official approach to
34 viewing LTTng events as they are emitted.
36 The relay daemon listens by default on all network interfaces to gather
37 trace data, but only on localhost for LTTng live connections.
39 The relay daemon does not require any particular permissions, as long as
40 it can write to the output directory and listen on the configured ports.
41 If a user is within a secured network and/or has proper firewall
42 settings, `lttng-relayd` can listen to LTTng live connections from _all_
43 network interfaces by specifying
44 +--live-port=tcp://0.0.0.0:{default_network_viewer_port}+.
46 Once a trace has been streamed completely, the trace can be processed by
47 any tool that can process an LTTng trace located on the local
54 The relay daemon uses different output path patterns depending on:
57 * The connected peer's tracing session configuration.
58 * The connected peer's LTTng session daemon (see man:lttng-sessiond(8))
61 Consider the following variables:
64 Base output directory: `$LTTNG_HOME/lttng-traces` or the
65 argument of the option:--output option.
67 NOTE: `$LTTNG_HOME` defaults to `$HOME` when not explicitly set.
76 Unique tracing session date/time.
79 Custom trace path ('TRACEPATH' part of the man:lttng-create(1)
80 command's nloption:--set-url option's argument, if any).
82 The relay daemon output path patterns are:
84 Hostname grouping (without option:--group-output-by-session)::
85 Without a custom trace path:::
89 'BASE'/'HOSTNAME'/'SESSION'-'DATETIME'
92 With a custom trace path:::
96 'BASE'/'HOSTNAME'/'TRACEPATH'
99 Tracing session grouping (with option:--group-output-by-session)::
100 Without a custom trace path:::
101 The peer's LTTng session daemon version is at least 2.4::::
105 'BASE'/'SESSION'/'HOSTNAME'-'DATETIME'
109 Defaults to the hostname grouping pattern:
113 'BASE'/'HOSTNAME'/'SESSION'-'DATETIME'
116 With a custom trace path:::
117 The peer's LTTng session daemon version is at least 2.4::::
121 'BASE'/'SESSION'/'HOSTNAME'-'DATETIME'/'TRACEPATH'
125 Defaults to the hostname grouping pattern:
129 'BASE'/'HOSTNAME'/'TRACEPATH'
136 The option:--control-port, option:--data-port, and option:--live-port
137 options specify URLs.
139 The format of those URLs is:
142 tcp://('HOST' | 'IPADDR'):__PORT__
146 ('HOST' | 'IPADDR')::
147 Binding hostname or IP address (IPv6 address *must* be enclosed in
148 brackets (`[` and `]`); see
149 https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]).
159 option:-b, option:--background::
160 Start as Unix daemon, but keep file descriptors (console) open.
161 Use the option:--daemonize option instead to close the file
164 option:-d, option:--daemonize::
165 Start as Unix daemon, and close file descriptors (console). Use the
166 option:--background option instead to keep the file descriptors
169 option:-x, option:--disallow-clear::
170 Disallow clearing operations (see man:lttng-clear(1)).
172 See also the `LTTNG_RELAYD_DISALLOW_CLEAR` environment variable.
174 option:--fd-pool-size='SIZE'::
175 Set the size of the file descriptor pool to 'SIZE'.
177 'SIZE' is the maximum number of file descriptors that may be kept opened
178 simultaneously by the relay daemon.
180 Default: the soft `RLIMIT_NOFILE` resource limit of the process (see
183 option:-g 'GROUP', option:--group='GROUP'::
184 Use 'GROUP' as Unix tracing group (default: `tracing`).
186 option:-w 'PATH', option:--working-directory='PATH'::
187 Set the working directory of the processes the relay daemon creates
190 See also the `LTTNG_RELAYD_WORKING_DIRECTORY` environment variable.
192 option:-v, option:--verbose::
195 Three levels of verbosity are available, which are triggered by
196 appending additional `v` letters to the option
197 (that is, `-vv` and `-vvv`).
202 See the <<output-directory,Output directory>> section above for more
205 option:-p, option:--group-output-by-host::
206 Group the written trace directories by hostname (default).
208 option:-s, option:--group-output-by-session::
209 Group the written trace directories by tracing session name instead
212 option:-o 'PATH', option:--output='PATH'::
213 Set the base output directory of the written trace directories to
219 See the <<url-format,URL format>> section above for more information
220 about the syntax of the following 'URL' argument.
222 option:-C 'URL', option:--control-port='URL'::
223 Listen to control data on URL 'URL' (default:
224 +tcp://{default_network_control_bind_address}:{default_network_control_port}+).
226 option:-D 'URL', option:--data-port='URL'::
227 Listen to trace data on URL 'URL' (default:
228 +tcp://{default_network_data_bind_address}:{default_network_data_port}+).
230 option:-L 'URL', option:--live-port='URL'::
231 Listen to LTTng live connections on URL 'URL'
233 +tcp://{default_network_viewer_bind_address}:{default_network_viewer_port}+).
238 option:-h, option:--help::
241 option:-V, option:--version::
245 ENVIRONMENT VARIABLES
246 ---------------------
247 `LTTNG_ABORT_ON_ERROR`::
248 Set to 1 to abort the process after the first error is encountered.
250 `LTTNG_NETWORK_SOCKET_TIMEOUT`::
251 Socket connection, receive and send timeout (milliseconds). A value
252 of 0 or -1 uses the timeout of the operating system (default).
254 `LTTNG_RELAYD_DISALLOW_CLEAR`::
255 Set to 1 to disallow clearing operations (see man:lttng-clear(1)).
257 The option:--disallow-clear option overrides this variable.
259 `LTTNG_RELAYD_HEALTH`::
260 Path to relay daemon health's socket.
262 `LTTNG_RELAYD_TCP_KEEP_ALIVE`::
263 Set to 1 to enable TCP keep-alive.
265 The TCP keep-alive mechanism allows the detection of dead peers
266 (man:lttng-sessiond(8)) in cases of unclean termination
267 (for example, a hard reset) of a peer.
269 Supported on Linux and Solaris only. The default behaviour of the TCP
270 keep-alive mechanism is OS-specific.
272 Search for `tcp_keepalive` in man:tcp(7) for more information.
274 `LTTNG_RELAYD_TCP_KEEP_ALIVE_ABORT_THRESHOLD`::
275 The time threshold in seconds to abort a TCP connection after the keep-alive
276 probing mechanism has failed.
278 Set to 0 or -1 to use the value chosen by the operating system (default).
280 Supported on Solaris 11 only.
282 Search for `tcp_keepalive_abort_threshold` in man:tcp(7) for more information.
284 `LTTNG_RELAYD_TCP_KEEP_ALIVE_IDLE_TIME`::
285 Number of seconds a connection needs to be idle before TCP begins
286 sending out keep-alive probes.
288 Set to 0 or -1 to use the value chosen by the operating system (default).
290 Supported on Linux and Solaris 11 only.
292 On Solaris{nbsp}11, the accepted values are -1, 0, and 10 to 864000.
294 Search for `tcp_keepalive_time` and `tcp_keepalive_interval`
295 in man:tcp(7) on Solaris 11 for more information.
297 `LTTNG_RELAYD_TCP_KEEP_ALIVE_MAX_PROBE_COUNT`::
298 Maximum number of TCP keep-alive probes to send before giving up and
299 killing the connection if no response is obtained from the other end.
301 Set to 0 or -1 to use the value chosen by the operating system (default).
303 Supported on Linux only.
305 Search for `tcp_keepalive_probes` in man:tcp(7) for more information.
307 `LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBE_INTERVAL`::
308 Number of seconds between TCP keep-alive probes.
310 Set to 0 or -1 to use the value chosen by the operating system (default).
312 Supported on Linux only.
314 Search for `tcp_keepalive_intvl` in man:tcp(7) for more information.
316 `LTTNG_RELAYD_WORKING_DIRECTORY`::
317 Working directory of the processes the relay daemon creates.
319 The option:--working-directory option overrides this variable.
324 `$LTTNG_HOME/.lttng`::
325 User LTTng runtime and configuration directory.
327 `$LTTNG_HOME/lttng-traces`::
328 Default base output directory of LTTng traces. This can be
329 overridden with the option:--output option.
331 NOTE: `$LTTNG_HOME` defaults to `$HOME` when not explicitly set.
348 As of this version, only the TCP protocol is supported for both control
349 and data ports. In future versions, TCP will remain the sole available
350 protocol for control data since those communications are low-volume and
351 need absolute reliability; trace data could be carried over UDP.
353 For an unprivileged user running `lttng-relayd`, the maximum number of
354 file descriptors per process is usually 1024. This limits the number of
355 connections and opened trace files. This limit can be configured with
359 include::common-footer.txt[]
365 man:lttng-sessiond(8),