| 1 | lttng-relayd(8) |
| 2 | =============== |
| 3 | :revdate: 2 April 2020 |
| 4 | |
| 5 | |
| 6 | NAME |
| 7 | ---- |
| 8 | lttng-relayd - LTTng 2 relay daemon |
| 9 | |
| 10 | |
| 11 | SYNOPSIS |
| 12 | -------- |
| 13 | [verse] |
| 14 | *lttng-relayd* [option:--background | option:--daemonize] [option:--config='PATH'] |
| 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] |
| 19 | |
| 20 | |
| 21 | DESCRIPTION |
| 22 | ----------- |
| 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. |
| 26 | |
| 27 | LTTng consists of Linux kernel modules (for Linux kernel tracing) and |
| 28 | dynamically loaded libraries (for user application and library tracing). |
| 29 | |
| 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. |
| 35 | |
| 36 | The relay daemon listens by default on all network interfaces to gather |
| 37 | trace data, but only on localhost for LTTng live connections. |
| 38 | |
| 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}+. |
| 45 | |
| 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 |
| 48 | file system. |
| 49 | |
| 50 | |
| 51 | [[output-directory]] |
| 52 | Output directory |
| 53 | ~~~~~~~~~~~~~~~~ |
| 54 | The relay daemon uses different output path patterns depending on: |
| 55 | |
| 56 | * Its configuration. |
| 57 | * The connected peer's tracing session configuration. |
| 58 | * The connected peer's LTTng session daemon (see man:lttng-sessiond(8)) |
| 59 | version. |
| 60 | |
| 61 | Consider the following variables: |
| 62 | |
| 63 | 'BASE':: |
| 64 | Base output directory: `$LTTNG_HOME/lttng-traces` or the |
| 65 | argument of the option:--output option. |
| 66 | + |
| 67 | NOTE: `$LTTNG_HOME` defaults to `$HOME` when not explicitly set. |
| 68 | |
| 69 | 'HOSTNAME':: |
| 70 | Peer's hostname. |
| 71 | |
| 72 | 'SESSION':: |
| 73 | Tracing session name. |
| 74 | |
| 75 | 'DATETIME':: |
| 76 | Unique tracing session date/time. |
| 77 | |
| 78 | 'TRACEPATH':: |
| 79 | Custom trace path ('TRACEPATH' part of the man:lttng-create(1) |
| 80 | command's nloption:--set-url option's argument, if any). |
| 81 | |
| 82 | The relay daemon output path patterns are: |
| 83 | |
| 84 | Hostname grouping (without option:--group-output-by-session):: |
| 85 | Without a custom trace path::: |
| 86 | + |
| 87 | -- |
| 88 | [verse] |
| 89 | 'BASE'/'HOSTNAME'/'SESSION'-'DATETIME' |
| 90 | -- |
| 91 | |
| 92 | With a custom trace path::: |
| 93 | + |
| 94 | -- |
| 95 | [verse] |
| 96 | 'BASE'/'HOSTNAME'/'TRACEPATH' |
| 97 | -- |
| 98 | |
| 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:::: |
| 102 | + |
| 103 | -- |
| 104 | [verse] |
| 105 | 'BASE'/'SESSION'/'HOSTNAME'-'DATETIME' |
| 106 | -- |
| 107 | |
| 108 | Otherwise:::: |
| 109 | Defaults to the hostname grouping pattern: |
| 110 | + |
| 111 | -- |
| 112 | [verse] |
| 113 | 'BASE'/'HOSTNAME'/'SESSION'-'DATETIME' |
| 114 | -- |
| 115 | |
| 116 | With a custom trace path::: |
| 117 | The peer's LTTng session daemon version is at least 2.4:::: |
| 118 | + |
| 119 | -- |
| 120 | [verse] |
| 121 | 'BASE'/'SESSION'/'HOSTNAME'-'DATETIME'/'TRACEPATH' |
| 122 | -- |
| 123 | |
| 124 | Otherwise:::: |
| 125 | Defaults to the hostname grouping pattern: |
| 126 | + |
| 127 | -- |
| 128 | [verse] |
| 129 | 'BASE'/'HOSTNAME'/'TRACEPATH' |
| 130 | -- |
| 131 | |
| 132 | |
| 133 | [[url-format]] |
| 134 | URL format |
| 135 | ~~~~~~~~~~ |
| 136 | The option:--control-port, option:--data-port, and option:--live-port |
| 137 | options specify URLs. |
| 138 | |
| 139 | The format of those URLs is: |
| 140 | |
| 141 | [verse] |
| 142 | tcp://('HOST' | 'IPADDR'):__PORT__ |
| 143 | |
| 144 | with: |
| 145 | |
| 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]). |
| 150 | |
| 151 | 'PORT':: |
| 152 | TCP port. |
| 153 | |
| 154 | |
| 155 | OPTIONS |
| 156 | ------- |
| 157 | Daemon |
| 158 | ~~~~~~ |
| 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 |
| 162 | descriptors. |
| 163 | |
| 164 | option:-f 'PATH', option:--config='PATH':: |
| 165 | Load relay daemon configuration from path 'PATH'. |
| 166 | |
| 167 | option:-d, option:--daemonize:: |
| 168 | Start as Unix daemon, and close file descriptors (console). Use the |
| 169 | option:--background option instead to keep the file descriptors |
| 170 | open. |
| 171 | |
| 172 | option:-x, option:--disallow-clear:: |
| 173 | Disallow clearing operations (see man:lttng-clear(1)). |
| 174 | + |
| 175 | See also the `LTTNG_RELAYD_DISALLOW_CLEAR` environment variable. |
| 176 | |
| 177 | option:--fd-pool-size='SIZE':: |
| 178 | Set the size of the file descriptor pool to 'SIZE'. |
| 179 | + |
| 180 | 'SIZE' is the maximum number of file descriptors that may be kept opened |
| 181 | simultaneously by the relay daemon. |
| 182 | + |
| 183 | Default: the soft `RLIMIT_NOFILE` resource limit of the process (see |
| 184 | man:getrlimit(2)). |
| 185 | |
| 186 | option:-g 'GROUP', option:--group='GROUP':: |
| 187 | Use 'GROUP' as Unix tracing group (default: `tracing`). |
| 188 | |
| 189 | option:-w 'PATH', option:--working-directory='PATH':: |
| 190 | Set the working directory of the processes the relay daemon creates |
| 191 | to 'PATH'. |
| 192 | + |
| 193 | See also the `LTTNG_RELAYD_WORKING_DIRECTORY` environment variable. |
| 194 | |
| 195 | option:-v, option:--verbose:: |
| 196 | Increase verbosity. |
| 197 | + |
| 198 | Three levels of verbosity are available, which are triggered by |
| 199 | appending additional `v` letters to the option |
| 200 | (that is, `-vv` and `-vvv`). |
| 201 | |
| 202 | |
| 203 | Output |
| 204 | ~~~~~~ |
| 205 | See the <<output-directory,Output directory>> section above for more |
| 206 | information. |
| 207 | |
| 208 | option:-p, option:--group-output-by-host:: |
| 209 | Group the written trace directories by hostname (default). |
| 210 | |
| 211 | option:-s, option:--group-output-by-session:: |
| 212 | Group the written trace directories by tracing session name instead |
| 213 | of by hostname. |
| 214 | |
| 215 | option:-o 'PATH', option:--output='PATH':: |
| 216 | Set the base output directory of the written trace directories to |
| 217 | 'PATH'. |
| 218 | |
| 219 | |
| 220 | Ports |
| 221 | ~~~~~ |
| 222 | See the <<url-format,URL format>> section above for more information |
| 223 | about the syntax of the following 'URL' argument. |
| 224 | |
| 225 | option:-C 'URL', option:--control-port='URL':: |
| 226 | Listen to control data on URL 'URL' (default: |
| 227 | +tcp://{default_network_control_bind_address}:{default_network_control_port}+). |
| 228 | |
| 229 | option:-D 'URL', option:--data-port='URL':: |
| 230 | Listen to trace data on URL 'URL' (default: |
| 231 | +tcp://{default_network_data_bind_address}:{default_network_data_port}+). |
| 232 | |
| 233 | option:-L 'URL', option:--live-port='URL':: |
| 234 | Listen to LTTng live connections on URL 'URL' |
| 235 | (default: |
| 236 | +tcp://{default_network_viewer_bind_address}:{default_network_viewer_port}+). |
| 237 | |
| 238 | |
| 239 | Program information |
| 240 | ~~~~~~~~~~~~~~~~~~~ |
| 241 | option:-h, option:--help:: |
| 242 | Show help. |
| 243 | |
| 244 | option:-V, option:--version:: |
| 245 | Show version. |
| 246 | |
| 247 | |
| 248 | ENVIRONMENT VARIABLES |
| 249 | --------------------- |
| 250 | `LTTNG_ABORT_ON_ERROR`:: |
| 251 | Set to 1 to abort the process after the first error is encountered. |
| 252 | |
| 253 | `LTTNG_NETWORK_SOCKET_TIMEOUT`:: |
| 254 | Socket connection, receive and send timeout (milliseconds). A value |
| 255 | of 0 or -1 uses the timeout of the operating system (default). |
| 256 | |
| 257 | `LTTNG_RELAYD_DISALLOW_CLEAR`:: |
| 258 | Set to 1 to disallow clearing operations (see man:lttng-clear(1)). |
| 259 | + |
| 260 | The option:--disallow-clear option overrides this variable. |
| 261 | |
| 262 | `LTTNG_RELAYD_HEALTH`:: |
| 263 | Path to relay daemon health's socket. |
| 264 | |
| 265 | `LTTNG_RELAYD_TCP_KEEP_ALIVE`:: |
| 266 | Set to 1 to enable TCP keep-alive. |
| 267 | + |
| 268 | The TCP keep-alive mechanism allows the detection of dead peers |
| 269 | (man:lttng-sessiond(8)) in cases of unclean termination |
| 270 | (for example, a hard reset) of a peer. |
| 271 | + |
| 272 | Supported on Linux and Solaris only. The default behaviour of the TCP |
| 273 | keep-alive mechanism is OS-specific. |
| 274 | + |
| 275 | Search for `tcp_keepalive` in man:tcp(7) for more information. |
| 276 | |
| 277 | `LTTNG_RELAYD_TCP_KEEP_ALIVE_ABORT_THRESHOLD`:: |
| 278 | The time threshold in seconds to abort a TCP connection after the keep-alive |
| 279 | probing mechanism has failed. |
| 280 | + |
| 281 | Set to 0 or -1 to use the value chosen by the operating system (default). |
| 282 | + |
| 283 | Supported on Solaris 11 only. |
| 284 | + |
| 285 | Search for `tcp_keepalive_abort_threshold` in man:tcp(7) for more information. |
| 286 | |
| 287 | `LTTNG_RELAYD_TCP_KEEP_ALIVE_IDLE_TIME`:: |
| 288 | Number of seconds a connection needs to be idle before TCP begins |
| 289 | sending out keep-alive probes. |
| 290 | + |
| 291 | Set to 0 or -1 to use the value chosen by the operating system (default). |
| 292 | + |
| 293 | Supported on Linux and Solaris 11 only. |
| 294 | + |
| 295 | On Solaris{nbsp}11, the accepted values are -1, 0, and 10 to 864000. |
| 296 | + |
| 297 | Search for `tcp_keepalive_time` and `tcp_keepalive_interval` |
| 298 | in man:tcp(7) on Solaris 11 for more information. |
| 299 | |
| 300 | `LTTNG_RELAYD_TCP_KEEP_ALIVE_MAX_PROBE_COUNT`:: |
| 301 | Maximum number of TCP keep-alive probes to send before giving up and |
| 302 | killing the connection if no response is obtained from the other end. |
| 303 | + |
| 304 | Set to 0 or -1 to use the value chosen by the operating system (default). |
| 305 | + |
| 306 | Supported on Linux only. |
| 307 | + |
| 308 | Search for `tcp_keepalive_probes` in man:tcp(7) for more information. |
| 309 | |
| 310 | `LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBE_INTERVAL`:: |
| 311 | Number of seconds between TCP keep-alive probes. |
| 312 | + |
| 313 | Set to 0 or -1 to use the value chosen by the operating system (default). |
| 314 | + |
| 315 | Supported on Linux only. |
| 316 | + |
| 317 | Search for `tcp_keepalive_intvl` in man:tcp(7) for more information. |
| 318 | |
| 319 | `LTTNG_RELAYD_WORKING_DIRECTORY`:: |
| 320 | Working directory of the processes the relay daemon creates. |
| 321 | + |
| 322 | The option:--working-directory option overrides this variable. |
| 323 | |
| 324 | |
| 325 | FILES |
| 326 | ----- |
| 327 | `$LTTNG_HOME/.lttng`:: |
| 328 | User LTTng runtime and configuration directory. |
| 329 | |
| 330 | `$LTTNG_HOME/lttng-traces`:: |
| 331 | Default base output directory of LTTng traces. This can be |
| 332 | overridden with the option:--output option. |
| 333 | |
| 334 | NOTE: `$LTTNG_HOME` defaults to `$HOME` when not explicitly set. |
| 335 | |
| 336 | |
| 337 | EXIT STATUS |
| 338 | ----------- |
| 339 | *0*:: |
| 340 | Success |
| 341 | |
| 342 | *1*:: |
| 343 | Error |
| 344 | |
| 345 | *3*:: |
| 346 | Fatal error |
| 347 | |
| 348 | |
| 349 | LIMITATIONS |
| 350 | ----------- |
| 351 | As of this version, only the TCP protocol is supported for both control |
| 352 | and data ports. In future versions, TCP will remain the sole available |
| 353 | protocol for control data since those communications are low-volume and |
| 354 | need absolute reliability; trace data could be carried over UDP. |
| 355 | |
| 356 | For an unprivileged user running `lttng-relayd`, the maximum number of |
| 357 | file descriptors per process is usually 1024. This limits the number of |
| 358 | connections and opened trace files. This limit can be configured with |
| 359 | *ulimit*(3). |
| 360 | |
| 361 | |
| 362 | include::common-footer.txt[] |
| 363 | |
| 364 | |
| 365 | SEE ALSO |
| 366 | -------- |
| 367 | man:lttng(1), |
| 368 | man:lttng-sessiond(8), |
| 369 | man:lttng-crash(1), |
| 370 | man:lttng-ust(3), |
| 371 | man:babeltrace2(1) |