io.smallrye.opentracing.contrib.web.servlet.filter

Class TracingFilter

java.lang.Object

io.smallrye.opentracing.contrib.web.servlet.filter.TracingFilter

All Implemented Interfaces:

javax.servlet.Filter

public class TracingFilter
extends Object
implements javax.servlet.Filter

Tracing servlet filter. Filter can be programmatically added to ServletContext or initialized via web.xml. Following code examples show possible initialization:

 {
     @code
     TracingFilter filter = new TracingFilter(tracer);
     servletContext.addFilter("tracingFilter", filter);
 }
 

Or include filter in web.xml and:

 
  GlobalTracer.register(tracer);
  servletContext.setAttribute({@link TracingFilter#SPAN_DECORATORS}, listOfDecorators); // optional, if no present ServletFilterSpanDecorator.STANDARD_TAGS is applied
 
 

Current server span context is accessible via ServletRequest.getAttribute(String) with name SERVER_SPAN_CONTEXT.

Author:

Pavol Loffay

Field Summary

Fields

Modifier and Type	Field and Description
static String	SERVER_SPAN_CONTEXT Used as a key of ServletRequest.setAttribute(String, Object) to inject server span context
static String	SKIP_PATTERN Use as a key of ServletContext.setAttribute(String, Object) to skip pattern
static String	SPAN_DECORATORS Use as a key of ServletContext.setAttribute(String, Object) to set span decorators
protected io.opentracing.Tracer	tracer

Constructor Summary

Constructors

Constructor and Description
TracingFilter() Tracer instance has to be registered with GlobalTracer.register(Tracer).
TracingFilter(io.opentracing.Tracer tracer)
TracingFilter(io.opentracing.Tracer tracer, List<ServletFilterSpanDecorator> spanDecorators, Pattern skipPattern)

Method Summary

Modifier and Type	Method and Description
void	destroy()
void	doFilter(javax.servlet.ServletRequest servletRequest, javax.servlet.ServletResponse servletResponse, javax.servlet.FilterChain chain)
void	init(javax.servlet.FilterConfig filterConfig)
protected boolean	isTraced(javax.servlet.http.HttpServletRequest httpServletRequest, javax.servlet.http.HttpServletResponse httpServletResponse) It checks whether a request should be traced or not.
static io.opentracing.SpanContext	serverSpanContext(javax.servlet.ServletRequest servletRequest) Get context of server span.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SPAN_DECORATORS

public static final String SPAN_DECORATORS

Use as a key of ServletContext.setAttribute(String, Object) to set span decorators

SKIP_PATTERN

public static final String SKIP_PATTERN

Use as a key of ServletContext.setAttribute(String, Object) to skip pattern

SERVER_SPAN_CONTEXT

public static final String SERVER_SPAN_CONTEXT

Used as a key of ServletRequest.setAttribute(String, Object) to inject server span context

tracer

protected io.opentracing.Tracer tracer

Constructor Detail

TracingFilter

public TracingFilter()

Tracer instance has to be registered with GlobalTracer.register(Tracer).

TracingFilter

public TracingFilter(io.opentracing.Tracer tracer)

Parameters:

tracer -

TracingFilter

public TracingFilter(io.opentracing.Tracer tracer,
                     List<ServletFilterSpanDecorator> spanDecorators,
                     Pattern skipPattern)

Parameters:

tracer - tracer

spanDecorators - decorators

skipPattern - null or pattern to exclude certain paths from tracing e.g. "/health"

Method Detail

init

public void init(javax.servlet.FilterConfig filterConfig)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Filter

Throws:

javax.servlet.ServletException

doFilter

public void doFilter(javax.servlet.ServletRequest servletRequest,
                     javax.servlet.ServletResponse servletResponse,
                     javax.servlet.FilterChain chain)
              throws IOException,
                     javax.servlet.ServletException

Specified by:

doFilter in interface javax.servlet.Filter

Throws:

IOException

javax.servlet.ServletException

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Filter

isTraced

protected boolean isTraced(javax.servlet.http.HttpServletRequest httpServletRequest,
                           javax.servlet.http.HttpServletResponse httpServletResponse)

It checks whether a request should be traced or not.

Parameters:

httpServletRequest - request

httpServletResponse - response

Returns:

whether request should be traced or not

serverSpanContext

public static io.opentracing.SpanContext serverSpanContext(javax.servlet.ServletRequest servletRequest)

Get context of server span.

Parameters:

servletRequest - request

Returns:

server span context