Ops Check Logs

Ops: Check Logs

View and search logs across local and remote environments.

Argument: $ARGUMENTS — target and optional filter (e.g., local, local worker, staging errors, production 500, staging slow-queries)

Discovery

1. Read config/deploy.yml to discover the service name (used in CloudWatch log group naming)
2. Read docker-compose.yml to identify local service names for targeted log viewing
3. Discover the AWS region from deploy config or environment variables

Local Logs (Docker Compose)

All Services

docker compose logs --tail=100

Follow Mode (tail)

docker compose logs -f --tail=50

Specific Service

# Rails web server
docker compose logs --tail=100 web

# Solid Queue worker
docker compose logs --tail=100 worker

# PostgreSQL
docker compose logs --tail=100 postgres

Filter for Errors

docker compose logs --tail=500 web 2>&1 | grep -iE "(error|exception|fatal|500)"

Rails Development Log (if running outside Docker)

tail -n 100 log/development.log

Filter Rails Log for Slow Queries

grep -E "SLOW|ms\)" log/development.log | tail -20

Remote Logs (Kamal)

Tail Application Logs

kamal app logs -d {environment}

Follow Mode

kamal app logs -d {environment} -f

Specific Role

# Web role
kamal app logs --roles=web -d {environment}

# Worker role (Solid Queue)
kamal app logs --roles=worker -d {environment}

Remote Logs (CloudWatch via AWS CLI)

For advanced filtering and historical log access, use the AWS CLI directly.

Discover Log Groups

aws logs describe-log-groups \
  --region {aws-region} \
  --query 'logGroups[].logGroupName' \
  --output text | tr '\t' '\n' | grep -i "{app_name}"

Filter for Errors (last 30 minutes)

aws logs filter-log-events \
  --region {aws-region} \
  --log-group-name "{log-group}" \
  --start-time $(( ($(date +%s) - 1800) * 1000 )) \
  --filter-pattern "ERROR" \
  --query 'events[].message' \
  --output text

Filter for 500 Errors

aws logs filter-log-events \
  --region {aws-region} \
  --log-group-name "{log-group}" \
  --start-time $(( ($(date +%s) - 1800) * 1000 )) \
  --filter-pattern '"status=500"' \
  --query 'events[].message' \
  --output text

Filter for Slow Requests (> 1 second)

aws logs filter-log-events \
  --region {aws-region} \
  --log-group-name "{log-group}" \
  --start-time $(( ($(date +%s) - 3600) * 1000 )) \
  --filter-pattern '"duration" "1000"' \
  --query 'events[].message' \
  --output text

Tail Live Logs

aws logs tail "{log-group}" \
  --region {aws-region} \
  --follow \
  --since 10m

Specific Time Range

aws logs filter-log-events \
  --region {aws-region} \
  --log-group-name "{log-group}" \
  --start-time $(date -d "{start-time}" +%s000) \
  --end-time $(date -d "{end-time}" +%s000) \
  --query 'events[].message' \
  --output text

ECS Task Logs

For container-level logs (useful when the application fails to start):

# List recent tasks
aws ecs list-tasks \
  --cluster {cluster-name} \
  --service-name {service-name} \
  --region {aws-region} \
  --query 'taskArns[]' --output text

# Describe a task to find the log stream
aws ecs describe-tasks \
  --cluster {cluster-name} \
  --tasks {task-arn} \
  --region {aws-region} \
  --query 'tasks[0].containers[].{Name:name,Status:lastStatus,ExitCode:exitCode}' \
  --output table

Output Format

Report log findings as:

Include a summary of findings: total errors, warnings, and any patterns observed.