# Access Logs Who Calls Whom? {.subtitle} By default, logs are written to stdout, in text format. ## Configuration To enable the access logs: ```toml tab="File (TOML)" [accessLog] ``` ```yaml tab="File (YAML)" accessLog: {} ``` ```bash tab="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. ### `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. !!! info "Common Log Format" ```html - [] " " "" "" "" "" 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. ```toml tab="File (TOML)" # Configuring a buffer of 100 lines [accessLog] filePath = "/path/to/access.log" bufferingSize = 100 ``` ```yaml tab="File (YAML)" # Configuring a buffer of 100 lines accessLog: filePath: "/path/to/access.log" bufferingSize: 100 ``` ```bash tab="CLI" # Configuring a buffer of 100 lines --accesslog=true --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 ```toml tab="File (TOML)" # Configuring Multiple Filters [accessLog] filePath = "/path/to/access.log" format = "json" [accessLog.filters] statusCodes = ["200", "300-302"] retryAttempts = true minDuration = "10ms" ``` ```yaml tab="File (YAML)" # Configuring Multiple Filters accessLog: filePath: "/path/to/access.log" format: json filters: statusCodes: - "200" - "300-302" retryAttempts: true minDuration: "10ms" ``` ```bash tab="CLI" # Configuring Multiple Filters --accesslog=true --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 You can decide to limit the logged fields/headers to a given list with the `fields.names` and `fields.header` 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.header` is `drop`. ```toml tab="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" ``` ```yaml tab="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 ``` ```bash tab="CLI" # Limiting the Logs to Specific Fields --accesslog=true --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 ``` ??? info "Available Fields" | Field | Description | |-------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `StartUTC` | The time at which request processing started. | | `StartLocal` | The local time at which request processing started. | | `Duration` | The total time taken (in nanoseconds) by processing the response, including the origin server's time but not the log writing time. | | `FrontendName` | The name of the Traefik frontend. | | `BackendName` | The name of the Traefik backend. | | `BackendURL` | The URL of the Traefik backend. | | `BackendAddr` | The IP:port of the Traefik backend (extracted from `BackendURL`) | | `ClientAddr` | The remote address in its original form (usually IP:port). | | `ClientHost` | The remote IP address from which the client request was received. | | `ClientPort` | The remote TCP port from which the client request was received. | | `ClientUsername` | The username provided in the URL, if present. | | `RequestAddr` | The HTTP Host header (usually IP:port). This is treated as not a header by the Go API. | | `RequestHost` | The HTTP Host server name (not including port). | | `RequestPort` | The TCP port from the HTTP Host. | | `RequestMethod` | The HTTP method. | | `RequestPath` | The HTTP request URI, not including the scheme, host or port. | | `RequestProtocol` | The version of HTTP requested. | | `RequestScheme` | The HTTP scheme requested `http` or `https`. | | `RequestLine` | `RequestMethod` + `RequestPath` + `RequestProtocol` | | `RequestContentSize` | The number of bytes in the request entity (a.k.a. body) sent by the client. | | `OriginDuration` | The time taken by the origin server ('upstream') to return its response. | | `OriginContentSize` | The content length specified by the origin server, or 0 if unspecified. | | `OriginStatus` | The HTTP status code returned by the origin server. If the request was handled by this Traefik instance (e.g. with a redirect), then this value will be absent. | | `OriginStatusLine` | `OriginStatus` + Status code explanation | | `DownstreamStatus` | The HTTP status code returned to the client. | | `DownstreamStatusLine` | `DownstreamStatus` + Status code explanation | | `DownstreamContentSize` | The number of bytes in the response entity returned to the client. This is in addition to the "Content-Length" header, which may be present in the origin response. | | `RequestCount` | The number of requests received since the Traefik instance started. | | `GzipRatio` | The response body compression ratio achieved. | | `Overhead` | The processing time overhead caused by Traefik. | | `RetryAttempts` | The amount of attempts the request was retried. | ## 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.