github.com/smintz/nomad@v0.8.3/website/source/docs/job-specification/logs.html.md (about) 1 --- 2 layout: "docs" 3 page_title: "logs Stanza - Job Specification" 4 sidebar_current: "docs-job-specification-logs" 5 description: |- 6 The "logs" stanza configures the log rotation policy for a task's stdout and 7 stderr. Logging is enabled by default with sane defaults. The "logs" stanza 8 allows for finer-grained control over how Nomad handles log files. 9 --- 10 11 # `logs` Stanza 12 13 <table class="table table-bordered table-striped"> 14 <tr> 15 <th width="120">Placement</th> 16 <td> 17 <code>job -> group -> task -> **logs**</code> 18 </td> 19 </tr> 20 </table> 21 22 The `logs` stanza configures the log rotation policy for a task's `stdout` and 23 `stderr`. Logging is enabled by default with sane defaults (provided in the 24 parameters section below), and there is currently no way to disable logging for 25 tasks. The `logs` stanza allows for finer-grained control over how Nomad handles 26 log files. 27 28 Nomad's log rotation works by writing stdout/stderr output from tasks to a file 29 inside the `alloc/logs/` directory with the following format: 30 `<task-name>.<stdout/stderr>.<index>`. Output is written to a particular index, 31 starting at zero, till that log file hits the configured `max_file_size`. After, 32 a new file is created at `index + 1` and logs will then be written there. A log 33 file is never rolled over, instead Nomad will keep up to `max_files` worth of 34 logs and once that is exceeded, the log file with the lowest index is deleted. 35 36 ```hcl 37 job "docs" { 38 group "example" { 39 task "server" { 40 logs { 41 max_files = 10 42 max_file_size = 10 43 } 44 } 45 } 46 } 47 ``` 48 49 For information on how to interact with logs after they have been configured, 50 please see the [`nomad alloc logs`][logs-command] command. 51 52 ## `logs` Parameters 53 54 - `max_files` `(int: 10)` - Specifies the maximum number of rotated files Nomad 55 will retain for `stdout` and `stderr`. Each stream is tracked individually, so 56 specifying a value of 2 will create 4 files - 2 for stdout and 2 for stderr 57 58 - `max_file_size` `(int: 10)` - Specifies the maximum size of each rotated file 59 in `MB`. If the amount of disk resource requested for the task is less than 60 the total amount of disk space needed to retain the rotated set of files, 61 Nomad will return a validation error when a job is submitted. 62 63 ## `logs` Examples 64 65 The following examples only show the `logs` stanzas. Remember that the 66 `logs` stanza is only valid in the placements listed above. 67 68 ### Configure Defaults 69 70 This example shows a default logging configuration. Yes, it is empty on purpose. 71 Nomad automatically enables logging with sane defaults as described in the 72 parameters section above. 73 74 ```hcl 75 ``` 76 77 ### Customization 78 79 This example asks Nomad to retain 3 rotated files for each of `stderr` and 80 `stdout`, each a maximum size of 5 MB per file. The minimum disk space this 81 would require is 30 MB (3 `stderr` + 3 `stdout` × 5 MB = 30 MB). 82 83 ```hcl 84 logs { 85 max_files = 3 86 max_file_size = 5 87 } 88 ``` 89 90 [logs-command]: /docs/commands/alloc/logs.html "Nomad logs command"