Jaeger is a platform created by Uber and open sourced to collect tracing data across multiple micro-services. The docker image jaegertracing/all-in-one does not setup or use certain components such as Elasticsearch and Cassandra.
The UDP port 6831 is used to receive tracing data with a fallback http port of 14268 provided in case there are any issues with UDP packet limits.
The Jaeger UI (built pleasingly in React) is available at localhost:16686.
The Jaeger UI is managed by the jaeger-query microservice, reloading the component multiple times will show traces for jaeger-query.
The HOTRoD Example Application:
An example ride sharing application is provided as an example:
docker run --rm -it \
--link jaeger \
-p8080-8083:8080-8083 \
jaegertracing/example-hotrod:1.6 \
all \
--jaeger-agent.host-port=jaeger:6831
The tracing platform can illustrate the architecture of the microservices as a Directed Acyclic Graph (DAG).
Each trace has a timeline view which represents all the spans within the transaction, each span can either be a call internal to a microservice or calls between microservices.
Logs are collected with contextual tracing information within each span.
Each span can have tags and logs, both of these contain contextual information
Tags are contextual information applied to the whole span. Span logs are events that occured during a span's execution. Each log has a timestamp to record when the event occured.
Semantic Data Conventions are provided by the OpenTracing Spec, some well known tags are described there.
Use these spans to check latency on the timeline view.