Access Logs

Who Calls Whom?

By default, logs are written to stdout, in text format.

Configuration

To enable the access logs:

File (YAML)

accessLog: {}

File (TOML)

[accessLog]

CLI

--accesslog=true

filePath

By default access logs are written to the standard output. To write the logs into a log file, use the filePath option.

File (YAML)

accessLog:
  filePath: "/path/to/access.log"

File (TOML)

[accessLog]
  filePath = "/path/to/access.log"

CLI

--accesslog.filepath=/path/to/access.log

format

By default, logs are written using the Common Log Format (CLF). To write logs in JSON, use json in the format option. If the given format is unsupported, the default (CLF) is used instead.

Common Log Format

<remote_IP_address> - <client_user_name_if_available> [<timestamp>] "<request_method> <request_path> <request_protocol>" <origin_server_HTTP_status> <origin_server_content_size> "<request_referrer>" "<request_user_agent>" <number_of_requests_received_since_Traefik_started> "<Traefik_router_name>" "<Traefik_server_URL>" <request_duration_in_ms>ms

bufferingSize

To write the logs in an asynchronous fashion, specify a bufferingSize option. This option represents the number of log lines Traefik will keep in memory before writing them to the selected output. In some cases, this option can greatly help performances.

File (YAML)

# Configuring a buffer of 100 lines
accessLog:
  filePath: "/path/to/access.log"
  bufferingSize: 100

File (TOML)

# Configuring a buffer of 100 lines
[accessLog]
  filePath = "/path/to/access.log"
  bufferingSize = 100

CLI

# Configuring a buffer of 100 lines
--accesslog.filepath=/path/to/access.log
--accesslog.bufferingsize=100

Filtering

To filter logs, you can specify a set of filters which are logically “OR-connected”. Thus, specifying multiple filters will keep more access logs than specifying only one.

The available filters are:

• statusCodes, to limit the access logs to requests with a status codes in the specified range
• retryAttempts, to keep the access logs when at least one retry has happened
• minDuration, to keep access logs when requests take longer than the specified duration (provided in seconds or as a valid duration format, see time.ParseDuration)

File (YAML)

# Configuring Multiple Filters
accessLog:
  filePath: "/path/to/access.log"
  format: json
  filters:
    statusCodes:
      - "200"
      - "300-302"
    retryAttempts: true
    minDuration: "10ms"

File (TOML)

# Configuring Multiple Filters
[accessLog]
  filePath = "/path/to/access.log"
  format = "json"
  [accessLog.filters]
    statusCodes = ["200", "300-302"]
    retryAttempts = true
    minDuration = "10ms"

CLI

# Configuring Multiple Filters
--accesslog.filepath=/path/to/access.log
--accesslog.format=json
--accesslog.filters.statuscodes=200,300-302
--accesslog.filters.retryattempts
--accesslog.filters.minduration=10ms

Limiting the Fields/Including Headers

You can decide to limit the logged fields/headers to a given list with the fields.names and fields.headers options.

Each field can be set to:

• keep to keep the value
• drop to drop the value
• redact to replace the value with “redacted”

The defaultMode for fields.names is keep.

The defaultMode for fields.headers is drop.

File (YAML)

# Limiting the Logs to Specific Fields
accessLog:
  filePath: "/path/to/access.log"
  format: json
  fields:
    defaultMode: keep
    names:
      ClientUsername: drop
    headers:
      defaultMode: keep
      names:
          User-Agent: redact
          Authorization: drop
          Content-Type: keep

File (TOML)

# Limiting the Logs to Specific Fields
[accessLog]
  filePath = "/path/to/access.log"
  format = "json"
  [accessLog.fields]
    defaultMode = "keep"
    [accessLog.fields.names]
      "ClientUsername" = "drop"
    [accessLog.fields.headers]
      defaultMode = "keep"
      [accessLog.fields.headers.names]
        "User-Agent" = "redact"
        "Authorization" = "drop"
        "Content-Type" = "keep"

CLI

# Limiting the Logs to Specific Fields
--accesslog.filepath=/path/to/access.log
--accesslog.format=json
--accesslog.fields.defaultmode=keep
--accesslog.fields.names.ClientUsername=drop
--accesslog.fields.headers.defaultmode=keep
--accesslog.fields.headers.names.User-Agent=redact
--accesslog.fields.headers.names.Authorization=drop
--accesslog.fields.headers.names.Content-Type=keep

Available Fields

Log Rotation

Traefik will close and reopen its log files, assuming they’re configured, on receipt of a USR1 signal. This allows the logs to be rotated and processed by an external program, such as logrotate.

Warning

This does not work on Windows due to the lack of USR signals.

Time Zones

Traefik will timestamp each log line in UTC time by default.

It is possible to configure the Traefik to timestamp in a specific timezone by ensuring the following configuration has been made in your environment:

1. Provide time zone data to /etc/localtime or /usr/share/zoneinfo (based on your distribution) or set the environment variable TZ to the desired timezone
2. Specify the field StartLocal by dropping the field named StartUTC (available on the default Common Log Format (CLF) as well as JSON)

Example utilizing Docker Compose:

version: "3.7"
services:
  traefik:
    image: traefik:v2.7
    environment:
      - TZ=US/Alaska
    command:
      - --accesslog.fields.names.StartUTC=drop
      - --providers.docker
    ports:
      - 80:80
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock