Monitoring HTTP Access Logs

HTTP access logs help you monitor your application's usage with information such as the persons who access it, how many hits it received, what the errors are, etc. This information is useful for troubleshooting errors.

In API Manager, access logs can be configured for both servlet transport and PassThrough or NIO transports in API Gateway.

Configuring access logs for the HTTP Servlet transport

In WSO2 API Manager, the access logs can be generated for HTTP servlet transport which works on 9443/9763 default ports. HTTP servlet transport access logs are useful for analysing operational/admin-level access details.

Following is a sample of access log entries which can be monitored via <APIM_HOME>repository/logs/http_access_.log file by default.

- 127.0.0.1 - - [12/Dec/2019:16:53:29 +0530] "POST /token HTTP/1.1" - 125 "-" "-"
- 127.0.0.1  - [12/Dec/2019:16:53:29 +0530] "- - " 200 - "-" "-"
- 127.0.0.1 - - [12/Dec/2019:16:53:29 +0530] "POST /oauth2/token HTTP/1.1" - - "-" "Synapse-PT-HttpComponents-NIO"
- 127.0.0.1  - [12/Dec/2019:16:53:29 +0530] "- - " 200 - "-" "-"
- 127.0.0.1 - - [12/Dec/2019:16:54:38 +0530] "OPTIONS /pizzashack/1.0.0/menu HTTP/1.1" - - "https://localhost:9443/devportal/apis/462a90a2-9f2b-423f-9f58-28b95c30a184/test" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36"
- 127.0.0.1  - [12/Dec/2019:16:54:38 +0530] "- - " 200 - "-" "-"
- 127.0.0.1 - - [12/Dec/2019:16:54:38 +0530] "GET /pizzashack/1.0.0/menu HTTP/1.1" - - "https://localhost:9443/devportal/apis/462a90a2-9f2b-423f-9f58-28b95c30a184/test" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36"
- 127.0.0.1 - - [12/Dec/2019:16:54:38 +0530] "GET /am/sample/pizzashack/v1/api/menu HTTP/1.1" - - "https://localhost:9443/devportal/apis/462a90a2-9f2b-423f-9f58-28b95c30a184/test" "Synapse-PT-HttpComponents-NIO"

As the runtime of WSO2 API Manager is based on Apache Tomcat, you can use the Access_Log_Valve variable in Tomcat as explained below to configure access logs to the HTTP servlet transport:

Configuring access logs for PassThrough or NIO transports in API Gateway

By default, access logs related to service/API invocation are disabled for performance reasons in the above products. You should enable these access log only for troubleshooting errors.

Follow the steps given below to enable access logs for the PassThrough or NIO transport.

  1. Open <APIM_HOME>/conf/log4j2.properties file and add following configuration for PassThroughAccess logger.

    logger.PassThroughAccess.name = org.apache.synapse.transport.http.access
    logger.PassThroughAccess.level = INFO
  2. Append PassThroughAccess logger name to loggers configuration which is a comma separated list of all active loggers.

    loggers = PassThroughAccess, AUDIT_LOG, SERVICE_LOGGER, trace-messages,
  3. Create a file named access-log.properties in <API-M_HOME>/repository/conf/ location with the following configuration and customize it as required.

    Warning

    All the supported options are in the following file. Therefore, make sure to uncomment the required options to enable them as required.

    # Default access log pattern
    #access_log_pattern=%{X-Forwarded-For}i %h %l %u %t \”%r\” %s %b \”%{Referer}i\” \”%{User-Agent}i\”
    # combinded log pattern
    #access_log_pattern=%h %l %u %t \”%r\” %s %b \”%{Referer}i\” \”%{User-Agent}i\”
    access_log_pattern=time=%t remoteHostname=%h localPort=%p localIP=%A requestMethod=%m requestURL=%U remoteIP=%a requestProtocol=%H HTTPStatusCode=%s queryString=%q
    # common log pattern
    #access_log_pattern=%h %l %u %t \”%r\” %s %b
    # file prefix
    access_log_prefix=http_gw
    # file suffix
    access_log_suffix=.log
    # file date format
    access_log_file_date_format=yyyy-MM-dd
    #access_log_directory=”/logs”

    You can customize the default format and the configurations of gateway access logs using following properties that you can define in access-log.properties.

    access_log_directory Add this property ONLY if you want to change the default location of the log file. By default, the product is configured to store access logs in the /repository/logs directory.
    access_log_prefix

    The prefix added to the log file's name. The default value is as follows:

    access_log_prefix=http_access_
    access_log_suffix

    The suffix added to the log file's name. The default value is as follows:

    access_log_suffix=.log
    access_log_file_date_format

    The date format used in access logs. The default value is as follows:

    access_log_file_date_format=yyyy-MM-dd
    access_log_pattern

    The attribute defines the format for the log pattern, which consists of the information fields from the requests and responses that should be logged. The pattern format is created using the following attributes:

    • A standard value to represent a particular string. For example, "%h" represents the remote host name in the request. Note that all the string replacement values supported by Tomcat are NOT supported for the PassThrough transport's access logs. The list of supported values are given below .

    • %{xxx}i is used to represent the header in the incoming request (xxx=header value).
    • %{xxx}o is used to represents the header in the outgoing request (xxx=header value).

    While you can use the above attributes to define a custom pattern, the standard patterns shown below can be used.

    By default, a modified version of the Apache combined log format is enabled in the ESB as shown below. Note that the "X-Forwarded-For" header is appended to the beginning of the usually combined log format. This correctly identifies the original node that sent the request (in situations where requests go through a proxy such as a load balancer). The "X-Forwarded-For" header must be present in the incoming request for this to be logged.

    access_log_pattern=%{X-Forwarded-For}i %h %l %u %t \"%r\" %s %b \"%{Referer}i\" \"%{User-Agent}i\"

  4. Add the following configuration in the /repository/conf/nhttp.properties file. You need to add this configuration in order to make sure that the access logs related to the PassThrough and NIO transports are rotated on a daily basis. If this configuration is not set, all the access log details related to the PassThrough and NIO transports will get logged in a single file. The date will be appended to the access log when it is rotated.

    nhttp.is.log.rotatable=true
  5. Then Restart the server.

  6. Invoke an API in API Gateway. Then, navigate to <APIM_HOME>/repository/logs/ directory and you will see a newly created log file called http_gw.log which contain API invocation related access logs.

Supported log pattern formats for the PassThrough transport

Attribute Description
%a

Remote IP address

%A

Local IP address

%b

Bytes sent, excluding HTTP headers, or '-' if zero

%B

Bytes sent, excluding HTTP headers

%c

Cookie value

%C

Accept header

%e

Accept Encoding

%E

Transfer Encoding

%h

Remote host name (or IP address if enableLookups for the connector is false)

%l

Remote logical username from identd (always returns '-')

%L

Accept Language

%k

Keep Alive

%m

Request method (GET, POST, etc.)

%n

Content Encoding

%r

Request Element

%s

HTTP status code of the response

%S

Accept Chatset

%t

Date and time, in Common Log Format

%T

Time taken to process the request in seconds.

%u

Remote user that was authenticated (if any), else '-'

%U

Requested URL path

%v

Local server name

%V

Vary Header

%x

Connection Header

%Z

Server Header

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