loki/examples/promtail-heroku/config.yml

server:
  http_listen_port: 9080
  grpc_listen_port: 0
  log_level: "info"

positions:
  filename: /tmp/positions.yaml

# This bit indicates what Loki instance to write the logs to. We’ll inject the
# details and credentials through environment variables
clients:
  - url: https://${LOKI_TENANT_ID}:${LOKI_TOKEN}@${LOKI_HOST}/loki/api/v1/push

scrape_configs:
  # Job name, that will be injected in each log line
  - job_name: ${JOB_NAME}

# Apply relabel to keep Heroku internal labels
relabel_configs:
  - source_labels: ["__heroku_drain_host"]
    target_label: "host"
  - source_labels: ["__heroku_drain_app"]
    target_label: "app"
  - source_labels: ["__heroku_drain_proc"]
    target_label: "proc"

    # Main heroku target configuration
    heroku_drain:
      server:
        http_listen_address: 0.0.0.0
        # $PORT is a special environment variable that Heroku fills with
        # port that’s accessible from outside the container. We indicate promtail
        # to listen for Heroku logs in it.
        http_listen_port: ${PORT}
        log_level: info
      # Tag each log entry with our job name
      labels:
        job: ${JOB_NAME}