Logs

Semaphore writes server logs to stdout and stores Task and Activity logs in a database, centralizing key log information and eliminating the need to back up log files separately. The only data stored on the file system is caching data.

Server log

Semaphore does not log to files. Instead, all application logs are written to stdout.
If Semaphore is running as a systemd service, you can view the logs with the following command:

journalctl -u semaphore.service -f

This provides a live (streaming) view of the logs.

Activity log

The Activity Log captures all user actions performed in Semaphore, including:

Adding or removing resources (e.g., Templates, Inventories, Repositories).
Adding or removing team members.
Starting or stopping tasks.

Pro version 2.10 and later

Semaphore Pro 2.10+ supports writing the Activity Log and Task log to a file. To enable this, add the following configuration to your config.json:

{
  "log": {
    "events": {
      "enabled": true,
      "logger": {
        "filename": "../events.log"
        // other logger options
      }
    },
    "tasks": {
      "enabled": true,
      "logger": {
        "filename": "../tasks.log"
        // other logger options
      }
    }
  }
}

Or you can do this using following environment variables:

export SEMAPHORE_EVENT_LOG_ENABLED=True
export SEMAPHORE_EVENT_LOG_PATH=./events.log

export SEMAPHORE_TASK_LOG_ENABLED=True
export SEMAPHORE_TASK_LOG_PATH=./tasks.log

Events logging options

Parameter	Environment Variables	Description
`enabled`	`SEMAPHORE_EVENT_LOG_ENABLED`	Enable event logging to file.
`format`	`SEMAPHORE_EVENT_LOG_FORMAT`	Log record format. Can be `raw` or `json`.
`logger`	`SEMAPHORE_EVENT_LOG_LOGGER`	Logger opitons.

Tasks logging options

Parameter	Environment Variables	Description
`enabled`	`SEMAPHORE_TASK_LOG_ENABLED`	Enable task logging to file.
`format`	`SEMAPHORE_TASK_LOG_FORMAT`	Log record format. Can be `raw` or `json`.
`logger`	`SEMAPHORE_TASK_LOG_LOGGER`	Logger opitons.

Logger options

Parameter	Type	Description
`filename`	String	Path and name of the file to write logs to. Backup log files will be retained in the same directory. It uses -lumberjack.log in temporary if empty.
`maxsize`	Integer	The maximum size in megabytes of the log file before it gets rotated. It defaults to 100 megabytes.
`maxage`	Integer	The maximum number of days to retain old log files based on the timestamp encoded in their filename. Note that a day is defined as 24 hours and may not exactly correspond to calendar days due to daylight savings, leap seconds, etc. The default is not to remove old log files based on age.
`maxbackups`	Integer	The maximum number of old log files to retain. The default is to retain all old log files (though MaxAge may still cause them to get deleted.)
`localtime`	Boolean	Determines if the time used for formatting the timestamps in backup files is the computer's local time. The default is to use UTC time.
`compress`	Boolean	Determines if the rotated log files should be compressed using gzip. The default is not to perform compression.

Each line in the file follows this format:

2024-01-03 12:00:34 user=234234 object=template action=delete

Task history

Semaphore stores information about task execution in the database. Task history provides a detailed view of all executed tasks, including their status and logs. You can monitor tasks in real time or review historical logs through the web interface.

Configuring task retention

By default, Semaphore stores all tasks in the database. If you run a large number of tasks, thet can occupy a significant amount of disk space.

You can configure how many tasks are retained per template using one of the following approaches:

Environment Variable
```
SEMAPHORE_MAX_TASKS_PER_TEMPLATE=30
```
config.json Option
```
{
  "max_tasks_per_template": 30
}
```

When the number of tasks exceeds this limit, the oldest Task Logs are automatically deleted.

Summary

Server log: Written to stdout; viewable via journalctl if running under systemd.
Activity and tasks log: Tracks all user actions. Optionally, Pro 2.10+ can write these to a file.
Task history: Stores real-time and historical task execution logs. Retention is configurable per template.

Following these guidelines ensures you have proper visibility into Semaphore UI operations while controlling storage usage and log retention.