Middleware-echoweb

Instrumentation

1. Create Cfg.yaml file
2. Create Routes.yaml file
3. Initailise Config with choice of sender, absolute path of CfgFile and RoutesFile along with EchoWeb Server pointer.
4. Call init function and pass the Config struct intialised above.
5. Copy tracer-config.yaml, tracer-routesRegistration.yaml file to container in Dockerfile

Example: tracer-config.yaml file:

cluster* : prod
shard* : 1
application : wavefrontHQ
service : wavefront-middleware
source : VMware
CustomApplicationTags* :
	staticTags:
		customApplicationTagKey : customApplicationTagValue
	jwtClaims**:
		- username
rateSampler* : 10
durationSampler* : 60

*optional parameter If no rate sampler is given it is taken as deterministic sampler ie all traces are sent to wavefront

**Middleware automatically parses jwt token to add the given claims as tags in the span

Example: tracer-routesRegistration.yaml

routesRegistration:
		/tracingapi/test.GET:
				routeSpecificTag: route-tag
				routeSpecifcMetaTags:
					routeSpecifcMetaTagKey: routeSpecifcMetaTagValue

Routes registration format: api-path.HTTP_METHOD

init function:

Using Direct Sender

func init() {
	cfgFile := "filePath of Cfg.yaml file"
	routesFile := "filePath of Routes.yaml file"

	config := new(Config)
	config.CfgFile = cfgFile
	config.RoutesFile= routesFile
	config.echoWeb = *echo.Echo
	config.DirectCfg = senders.DirectConfiguration
	
	//Initialising Global tracer
	err := InitTracer(config)

	if err != nil {
		/*
		Handle Error
		*/
	}
}

Using In-Direct Sender

func init() {
	cfgFile := "filePath of Cfg.yaml file"
	routesFile := "filePath of Routes.yaml file"

	config := new(Config)
	config.CfgFile = cfgFile
	config.RoutesFile= routesFile
	config.echoWeb = *echo.Echo
	config.DirectCfg = senders.ProxyConfiguration
	
	//Initialising Global tracer
	err := InitTracer(config)

	if err != nil {
		/*
		Handle Error
		*/
	}
}

Cross process context propagation

headers:= GetTracingHeadersToInject(c)

c - echo context

GetTracingHeadersToInject func returns headers which can be added to the call when making cross service calls. Context is propagated using headers which helps in stiching trace

Adding dynamic tags to Span

To add metadata derived during servicing the request

AddDynamicTags(c,tags)

c - echo context tags - key value pairs of strings

Contextual Logger

logger:= NewSpanLogger(c)

c - echo context Same usage as default go logger instance given by log lib in go. Ex: logger.Println("Logging") Logs are automatically injected span info including trace id, span id, and parent span id. Logs are sent to wavefront for each call

All the function exposed by standard Go Logger are exposed by custom logger with same usage

Other tracing methods exposed

For manual start of span

serverSpan,parentSpanId,err:= StartTraceSpan(c,operationName,tags)

c - echo context

For injecting headers in default http client request

httpRequest:= InjectTracerHTTP(tracer,span,httpReq)

Returns headers to be injected from span. To be used when manually starting span within the process

tags:= GetTracingHeadersToInjectFromSpan(tracer,span)

c - echo context

Returns headers to be injected from echo context. To be used when using middleware

GetTracingHeadersToInjectFromContext(c)