Logs & Debugging

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All S4E On-Prem services emit structured JSON logs to stdout, which Docker captures. This guide covers how to access, filter, and interpret those logs.

Accessing Logs

View Logs for a Specific Service

# Last 50 lines
docker logs s4e-core-1 --tail 50

# Follow in real time
docker logs s4e-core-1 -f

# Last 1 hour
docker logs s4e-core-1 --since 1h

# Since a specific time
docker logs s4e-core-1 --since "2026-04-24T10:00:00"

View Logs for All Services at Once

cd /opt/s4e/setup
docker compose logs --tail 20
docker compose logs -f   # follow all

Filter Logs by Level

Since logs are JSON, use grep or jq:

# Only errors
docker logs s4e-core-1 2>&1 | grep '"levelname": "ERROR"'

# Pretty-print with jq
docker logs s4e-core-1 2>&1 | jq 'select(.levelname == "ERROR")'

# Errors and warnings
docker logs s4e-core-1 2>&1 | jq 'select(.levelname | IN("ERROR","WARNING"))'

Log Format

All services emit structured JSON logs. Each line is a single JSON object:

{
  "asctime": "[24/Apr/2026:14:12:39 +0000]",
  "levelname": "INFO",
  "filename": "base_task.py",
  "lineno": 75,
  "message": "Task started",
  "task_key": "tasks.onprem.db-sync.action_catalog",
  "job_log_id": "2142",
  "category": "task",
  "event": "task_started",
  "duration_seconds": "0.138",
  "session_id": "a3f1c2d4-7e89-4b0f-95a6-2c8d3e1f4b72"
}

Key Fields

Field Description
asctime Timestamp of the log entry
levelname Log level: DEBUG, INFO, WARNING, ERROR, CRITICAL
filename Source file name
message Human-readable description
task_key Task identifier (scheduler tasks)
category Functional area (e.g., task, integration, scheduler)
event Specific event name (e.g., task_started, task_failed)
duration_seconds How long the operation took
integration_service External service name for integration logs
integration_status HTTP status code for integration calls

Adjusting Log Levels

To enable more verbose logging for a specific service, set LOG_LEVEL=DEBUG in .env and restart the service:

# Edit .env
nano /opt/s4e/setup/.env
# Add: LOG_LEVEL=DEBUG

# Restart the specific service
docker compose up -d --no-deps core

DEBUG in production

DEBUG logging produces very high log volume and may expose sensitive data. Only enable for active troubleshooting. Revert to INFO when done.

Next Steps

Resource Management Common Errors