| 1 | lttng-relayd(8) |
| 2 | =============== |
| 3 | |
| 4 | |
| 5 | NAME |
| 6 | ---- |
| 7 | lttng-relayd - LTTng 2 relay daemon |
| 8 | |
| 9 | |
| 10 | SYNOPSIS |
| 11 | -------- |
| 12 | [verse] |
| 13 | *lttng-relayd* [option:--background | option:--daemonize] |
| 14 | [option:--control-port='URL'] [option:--data-port='URL'] [option:--live-port='URL'] |
| 15 | [option:--output='PATH'] [option:-v | option:-vv | option:-vvv] |
| 16 | |
| 17 | |
| 18 | DESCRIPTION |
| 19 | ----------- |
| 20 | The http://lttng.org/[_Linux Trace Toolkit: next generation_] is an open |
| 21 | source software package used for correlated tracing of the Linux kernel, |
| 22 | user applications, and user libraries. |
| 23 | |
| 24 | LTTng consists of Linux kernel modules (for Linux kernel tracing) and |
| 25 | dynamically loaded libraries (for user application and library tracing). |
| 26 | |
| 27 | The _LTTng relay daemon_ is responsible for receiving trace data from |
| 28 | possibly remote LTTng session/consumer daemons and for writing it to |
| 29 | the local file system. The relay daemon also accepts _LTTng live_ |
| 30 | connections from compatible viewers; this is the official approach to |
| 31 | viewing LTTng events as they are emitted. |
| 32 | |
| 33 | The relay daemon listens by default on all network interfaces to gather |
| 34 | trace data, but only on localhost for LTTng live connections. |
| 35 | |
| 36 | The relay daemon does not require any particular permissions, as long as |
| 37 | it can write to the output directory and listen on the configured ports. |
| 38 | If a user is within a secured network and/or has proper firewall |
| 39 | settings, `lttng-relayd` can listen to LTTng live connections from _all_ |
| 40 | network interfaces by specifying `--live-port=tcp://0.0.0.0:5344`. |
| 41 | |
| 42 | Once a trace has been streamed completely, the trace can be processed by |
| 43 | any tool that can process an LTTng trace located on the local |
| 44 | file system. |
| 45 | |
| 46 | |
| 47 | [[output-directory]] |
| 48 | Output directory |
| 49 | ~~~~~~~~~~~~~~~~ |
| 50 | By default, the relay daemon writes the traces to: |
| 51 | |
| 52 | [verse] |
| 53 | $HOME/lttng-traces/'HOSTNAME'/'SESSION'/'DOMAIN' |
| 54 | |
| 55 | with: |
| 56 | |
| 57 | 'HOSTNAME':: |
| 58 | Remote hostname. |
| 59 | |
| 60 | 'SESSION':: |
| 61 | Full session name. |
| 62 | |
| 63 | 'DOMAIN':: |
| 64 | Tracing domain. |
| 65 | |
| 66 | You can override the default output directory prefix |
| 67 | (`$HOME/lttng-traces`) with the option:--output option. The other |
| 68 | parts depend on the remote configuration. |
| 69 | |
| 70 | |
| 71 | [[url-format]] |
| 72 | URL format |
| 73 | ~~~~~~~~~~ |
| 74 | The option:--control-port, option:--data-port, and option:--live-port |
| 75 | options specify URLs. |
| 76 | |
| 77 | The format of those URLs is: |
| 78 | |
| 79 | [verse] |
| 80 | tcp://('HOST' | 'IPADDR'):__PORT__ |
| 81 | |
| 82 | with: |
| 83 | |
| 84 | ('HOST' | 'IPADDR'):: |
| 85 | Binding hostname or IP address (IPv6 address *must* be enclosed in |
| 86 | brackets (`[` and `]`); see |
| 87 | https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]). |
| 88 | |
| 89 | 'PORT':: |
| 90 | TCP port. |
| 91 | |
| 92 | |
| 93 | OPTIONS |
| 94 | ------- |
| 95 | Daemon |
| 96 | ~~~~~~ |
| 97 | option:-b, option:--background:: |
| 98 | Start as Unix daemon, but keep file descriptors (console) open. |
| 99 | Use the option:--daemonize option instead to close the file |
| 100 | descriptors. |
| 101 | |
| 102 | option:-d, option:--daemonize:: |
| 103 | Start as Unix daemon, and close file descriptors (console). Use the |
| 104 | option:--background option instead to keep the file descriptors |
| 105 | open. |
| 106 | |
| 107 | option:-g, option:--group='GROUP':: |
| 108 | Use 'GROUP' as Unix tracing group (default: `tracing`). |
| 109 | |
| 110 | option:-o, option:--output='PATH':: |
| 111 | Set base directory of written trace data to 'PATH'. |
| 112 | + |
| 113 | See the <<output-directory,Output directory>> section above for more |
| 114 | information. |
| 115 | |
| 116 | option:-v, option:--verbose:: |
| 117 | Increase verbosity. |
| 118 | + |
| 119 | Three levels of verbosity are available, which are triggered by |
| 120 | appending additional `v` letters to the option |
| 121 | (that is, `-vv` and `-vvv`). |
| 122 | |
| 123 | |
| 124 | Ports |
| 125 | ~~~~~ |
| 126 | See the <<url-format,URL format>> section above for more information |
| 127 | about the syntax of the following options' 'URL' argument. |
| 128 | |
| 129 | option:-C, option:--control-port='URL':: |
| 130 | Listen to control data on URL 'URL' (default: `tcp://0.0.0.0:5342`). |
| 131 | |
| 132 | option:-D, option:--data-port='URL':: |
| 133 | Listen to trace data on URL 'URL' (default: `tcp://0.0.0.0:5343`). |
| 134 | |
| 135 | option:-L, option:--live-port='URL':: |
| 136 | Listen to LTTng live connections on URL 'URL' |
| 137 | (default: `tcp://0.0.0.0:5344`). |
| 138 | |
| 139 | |
| 140 | Program information |
| 141 | ~~~~~~~~~~~~~~~~~~~ |
| 142 | option:-h, option:--help:: |
| 143 | Show help. |
| 144 | |
| 145 | option:-V, option:--version:: |
| 146 | Show version. |
| 147 | |
| 148 | |
| 149 | ENVIRONMENT VARIABLES |
| 150 | --------------------- |
| 151 | `LTTNG_NETWORK_SOCKET_TIMEOUT`:: |
| 152 | Socket connection, receive and send timeout (milliseconds). A value |
| 153 | of 0 or -1 uses the timeout of the operating system (default). |
| 154 | |
| 155 | `LTTNG_RELAYD_HEALTH`:: |
| 156 | Path to relay daemon health's socket. |
| 157 | |
| 158 | |
| 159 | FILES |
| 160 | ----- |
| 161 | `$LTTNG_HOME/.lttng`:: |
| 162 | User LTTng runtime and configuration directory. |
| 163 | |
| 164 | `$LTTNG_HOME/lttng-traces`:: |
| 165 | Default output directory of LTTng traces. This can be overridden |
| 166 | with the option:--output option. |
| 167 | |
| 168 | NOTE: `$LTTNG_HOME` defaults to `$HOME` when not explicitly set. |
| 169 | |
| 170 | |
| 171 | EXIT STATUS |
| 172 | ----------- |
| 173 | *0*:: |
| 174 | Success |
| 175 | |
| 176 | *1*:: |
| 177 | Error |
| 178 | |
| 179 | *3*:: |
| 180 | Fatal error |
| 181 | |
| 182 | |
| 183 | LIMITATIONS |
| 184 | ----------- |
| 185 | As of this version, only the TCP protocol is supported for both control |
| 186 | and data ports. In future versions, TCP will remain the sole available |
| 187 | protocol for control data since those communications are low-volume and |
| 188 | need absolute reliability; trace data could be carried over UDP. |
| 189 | |
| 190 | For an unprivileged user running `lttng-relayd`, the maximum number of |
| 191 | file descriptors per process is usually 1024. This limits the number of |
| 192 | connections and opened trace files. This limit can be configured with |
| 193 | *ulimit*(3). |
| 194 | |
| 195 | |
| 196 | include::common-footer.txt[] |
| 197 | |
| 198 | |
| 199 | SEE ALSO |
| 200 | -------- |
| 201 | linklttng:lttng(1), |
| 202 | linklttng:lttng-sessiond(8), |
| 203 | linklttng:lttng-crash(1), |
| 204 | linklttng:lttng-ust(3), |
| 205 | linklttng:babeltrace(1) |