Distributed Tracing
Last updated
Last updated
When solving problems, it is important to know how clients and eva communicate with each other and how eva’s multiple modules talk to each other during the platform operation. As eva uses ISTIO as service mesh, it is possible to view dialogs systemic errors using an ISTIO package tool called Jaeger
Like Dapper and OpenZipkit, it is an open code distributed tracing system used to monitor and solve problems in microservices-based system such as:
Distributed context propagation
Distributed transactions monitoring
Root cause analysis
Service dependence analysis
Latency / performance optimization For further information, visit
Important: Before accessing Jaeger, keep in mind that it deals
with sensible information.
By default, Jaeger is not accessible through the internet. To access it, forward the port using the commands below:
If there are no errors, the following message appears:
With access to Jaeger, open your browser with the address: http://localhost:16686.
In the upper right corner, you can search for traces related to a specific “sessioncode”, fill the TAG field with a session ID such as:
sessionCode=0c2d189f-ebfc-4253-9152-77e29de946ad
If you need to search for traces of a failed requisition, use the command:
error=true sessionCode=0c2d189f-ebfc-4253-9152- 77e29de946ad
Before understanding na eva log in Jaeger, it is important to understand two concepts: span and trance.
A span is a logical work unit in Jaeger that has an operation name, start time and duration. Spans can be aligned and ordered to model causal relationships.
The Trace is the whole execution path though all modules that the requisition went though and can be viewed as an acyclical ordered spans chart.
With the search done and after clicking the selected trace:
It is possible to view the spans that happened during the call.
The red icon (!) helps to find the span containing the detailed error, for example:
ISTIO uses Envoy to integrate tracing by offering options to install several tracking back-ends and proxy configurations to send tracking spans automatically to them.
In eva, the default tool is Jaeger.
To make a correlation between the many requisitions that deals with a dialog, eva was changed to forward the headers below in all internal calls between modules. Doing so, it is possible to correlate independently from the instances in execution.
The headers defined in the Opentracing specifications are:
x-request-id
x-b3-traceid
x-b3-spanid
x-b3-parentspanid
x-b3-sampled
x-b3-flags
x-ot-span-context
Sometimes it is necessary to add a custom ID to the requisition to the broker so there is an identifier that can be used to search traces.
For further information, check
