WebServer Access Log

WebServer Access Log

Access logging in Helidon is done by a dedicated module that can be added to WebServer and configured.

Access logging is a Helidon WebServer Service and as such is executed in the order it is registered with WebServer routing. This implies that if you register it last and another Service or Handler finishes the request, the service will not be invoked.

Configuring Access Log in your code

Access log is configured in your code by registering it as a service with Routing

Routing.builder()
    .register(AccessLogSupport.create(config.get("server.access-log")))
    .get("/greet", myService)

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The order of registration is significant - make sure AccessLogSupport is registered first (even before security, tracing etc.).

Configuring Access Log in a configuration file

Access log can be configured as follows:

Access Log configuration file

server:
  port: 8080
  access-log:
    format: "%h %l %u %t %r %s %b %{Referer}i"

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All options shown above are also available programmatically when using builder.

Configuration options

The following configuration options can be defined:

Config key	Default value	Builder method	Description
`enabled`	`true`	`enabled(boolean)`	When this option is set to `false`, access logging will be disabled
`logger-name`	`io.helidon.webserver.AccessLog`	`loggerName(String)`	Name of the logger to use when writing log entries
`format`	`helidon`	`helidonLogFormat()`, `commonLogFormat()`, `add(AccessLogEntry entry)`	Configuration of access log output, when `helidon` is defined, the Helidon log format (see below) is used. Can be configured to explicitly define log entries (see below as well)

Supported Log Formats

Supported Log Entries

The following log entries are supported in Helidon:

Config format	Class (to use with builder)	Description
%h	`HostLogEntry`	IP address of the remote host
%l	`UserIdLogEntry`	Client identity, always undefined in Helidon
%u	`UserLogEntry`	The username of logged-in user (when Security is used)
%t	`TimestampLogEntry`	The current timestamp
%r	`RequestLineLogEntry`	The request line (method, path and HTTP version)
%s	`StatusLogEntry`	The HTTP status returned to the client
%b	`SizeLogEntry`	The response entity size (if available)
%D	`TimeTakenLogEntry`	The time taken in microseconds
%T	`TimeTakenLogEntry`	The time taken in seconds
%{`header-name`}i	`HeaderLogEntry`	Value of a header (can have multiple such specification to write multiple headers)

Currently we only support the entries defined above, with NO support for free text.

Helidon Log Format

When format is set to helidon, the format used is:

"%h %u %t %r %s %b %D"

The entries logged:

IP Address
Username of a logged-in user
Timestamp
Request Line
HTTP Status code
Entity size
Time taken (microseconds)

Access log example:

192.168.0.104 - [18/Jun/2019:22:28:55 +0200] "GET /greet/test HTTP/1.1" 200 53
0:0:0:0:0:0:0:1 - [18/Jun/2019:22:29:00 +0200] "GET /metrics/vendor HTTP/1.1" 200 1658
0:0:0:0:0:0:0:1 jack [18/Jun/2019:22:29:07 +0200] "PUT /greet/greeting HTTP/1.1" 200 21
0:0:0:0:0:0:0:1 jill [18/Jun/2019:22:29:12 +0200] "PUT /greet/greeting HTTP/1.1" 403 0
0:0:0:0:0:0:0:1 - [18/Jun/2019:22:29:17 +0200] "PUT /greet/greeting HTTP/1.1" 401 0

Common Log Format

When format is set to common, the format used is:

"%h %l %u %t %r %s %b"

The entries logged:

IP Address
Client identity
Username of a logged-in user
Timestamp
Request Line
HTTP Status code
Entity size

Access log example:

192.168.0.104   - - [18/Jun/2019:22:28:55 +0200] "GET /greet/test HTTP/1.1" 200 53
0:0:0:0:0:0:0:1 - - [18/Jun/2019:22:29:00 +0200] "GET /metrics/vendor HTTP/1.1" 200 1658
0:0:0:0:0:0:0:1 - jack [18/Jun/2019:22:29:07 +0200] "PUT /greet/greeting HTTP/1.1" 200 21
0:0:0:0:0:0:0:1 - jill [18/Jun/2019:22:29:12 +0200] "PUT /greet/greeting HTTP/1.1" 403 0
0:0:0:0:0:0:0:1 - - [18/Jun/2019:22:29:17 +0200] "PUT /greet/greeting HTTP/1.1" 401 0

Configuring Access Log with Java util logging

To support a separate file for Access log entries, Helidon provides a custom log handler, that extends the FileHandler.

To log to a file access.log with appending records after restart, you can use the following configuration in logging.properties:

Logging configuration file

io.helidon.webserver.accesslog.AccessLogHandler.level=INFO
io.helidon.webserver.accesslog.AccessLogHandler.pattern=access.log
io.helidon.webserver.accesslog.AccessLogHandler.append=true

io.helidon.webserver.AccessLog.level=INFO
io.helidon.webserver.AccessLog.useParentHandlers=false
io.helidon.webserver.AccessLog.handlers=io.helidon.webserver.accesslog.AccessLogHandler

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