---
name: "Plack::Middleware::AccessLog"
section: "3pm"
platform: "linux"
package: "libplack-perl"
version: "1.0051-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Plack::Middleware::AccessLog"
---

# Plack::Middleware::AccessLog(3pm)

Logs requests like Apache's log format

## NAME

Plack::Middleware::AccessLog - Logs requests like Apache's log format

## SYNOPSIS

```
  # in app.psgi
  use Plack::Builder;
  builder {
      enable "Plack::Middleware::AccessLog", format => "combined";
      $app;
  };
```

## DESCRIPTION

Plack::Middleware::AccessLog forwards the request to the given app and logs request and response details to the logger callback. The format can be specified using Apache-like format strings (or `"combined"` or `"common"` for the default formats). If none is specified `"combined"` is used.

This middleware uses calculable Content-Length by checking body type, and cannot log the time taken to serve requests. It also logs the request **before** the response is actually sent to the client. Use Plack::Middleware::AccessLog::Timed if you want to log details **after** the response is transmitted (more like a real web server) to the client.

This middleware is enabled by default when you run plackup as a default `"development"` environment.

## CONFIGURATION

- format

  ```
    enable "Plack::Middleware::AccessLog",
        format => '%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i"';
  ```

  Takes a format string (or a preset template `"combined"` or `"custom"`) to specify the log format. This middleware uses Apache::LogFormat::Compiler to generate access\_log lines. See more details on perldoc Apache::LogFormat::Compiler

  ```
     %%    a percent sign
     %h    REMOTE_ADDR from the PSGI environment, or -
     %l    remote logname not implemented (currently always -)
     %u    REMOTE_USER from the PSGI environment, or -
     %t    [local timestamp, in default format]
     %r    REQUEST_METHOD, REQUEST_URI and SERVER_PROTOCOL from the PSGI environment
     %s    the HTTP status code of the response
     %b    content length of the response
     %T    custom field for handling times in subclasses
     %D    custom field for handling sub-second times in subclasses
     %v    SERVER_NAME from the PSGI environment, or -
     %V    HTTP_HOST or SERVER_NAME from the PSGI environment, or -
     %p    SERVER_PORT from the PSGI environment
     %P    the worker's process id
     %m    REQUEST_METHOD from the PSGI environment
     %U    PATH_INFO from the PSGI environment
     %q    QUERY_STRING from the PSGI environment
     %H    SERVER_PROTOCOL from the PSGI environment
  ```

  Some of these format fields are only supported by middleware that subclasses `"AccessLog"`.

  In addition, custom values can be referenced, using `"%{name}"`, with one of the mandatory modifier flags `"i"`, `"o"` or `"t"`:

  ```
     %{variable-name}i    HTTP_VARIABLE_NAME value from the PSGI environment
     %{header-name}o      header-name header in the response
     %{time-format]t      localtime in the specified strftime format
  ```

- logger

  ```
    my $logger = Log::Dispatch->new(...);
    enable "Plack::Middleware::AccessLog",
        logger => sub { $logger->log(level => 'debug', message => @_) };
  ```

  Sets a callback to print log message to. It prints to the `"psgi.errors"` output stream by default.

- char\_handlers

  ```
    my $handlers = {
        'z' => sub {
            my ($env,$req) = @_;
            return $env->{HTTP_X_FORWARDED_FOR};
        }
    };
    enable "Plack::Middleware::AccessLog",
        format => '%z %{HTTP_X_FORWARDED_FOR|REMOTE_ADDR}Z',
        char_handlers => $handlers;
  ```

  Takes a hash reference and passes it to the underlying Apache::LogFormat::Compiler's `"char_handlers"`.  For more details see "ADD CUSTOM FORMAT STRING" in Apache::LogFormat::Compiler.

- block\_handlers

  ```
    my $handlers = {
        'Z' => sub {
            my ($block,$env,$req) = @_;
            # block eq 'HTTP_X_FORWARDED_FOR|REMOTE_ADDR'
            my ($main, $alt) = split('\|', $args);
            return exists $env->{$main} ? $env->{$main} : $env->{$alt};
        }
    };
    enable "Plack::Middleware::AccessLog",
        format => '%z %{HTTP_X_FORWARDED_FOR|REMOTE_ADDR}Z',
        block_handlers => $handlers;
  ```

  Takes a hash reference and passes it to the underlying Apache::LogFormat::Compiler's `"block_handlers"`.  For more details see "ADD CUSTOM FORMAT STRING" in Apache::LogFormat::Compiler.

## AUTHORS

Tatsuhiko Miyagawa

Masahiro Nagano

## SEE ALSO

Apache::LogFormat::Compiler, \<http://httpd.apache.org/docs/2.2/mod/mod\_log\_config.html\> Rack::CustomLogger