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101 lines
3.0 KiB
ReStructuredText
101 lines
3.0 KiB
ReStructuredText
JAEGER- DISTRIBUTED TRACING
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===========================
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Jaeger provides ready to use tracing services for distributed
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systems and is becoming the widely used standard because of their simplicity and
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standardization.
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BASIC ARCHITECTURE AND TERMINOLOGY
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----------------------------------
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* TRACE: A trace shows the data/execution path through a system.
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* SPAN: A single unit of a trace, it is a data structure that stores
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information like operation name, timestamps, ordering in a trace.
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* JAEGER CLIENT: language-specific implementations of the OpenTracing API.
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* JAEGER AGENT: a daemon that listens for spans sent over User Datagram Protocol.
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The agent is meant to be placed on the same host as the instrumented
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application. (acts like a sidecar listener)
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* JAEGER COLLECTOR: Jaeger agent sends the spans to this daemon which then
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stitches the spans together to form a trace(if enabled, also persists a database
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for these traces)
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* JAEGER QUERY AND CONSOLE FRONTEND: UI based frontend to checkout the jaeger
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traces, navigate to http://<jaeger frontend host>:16686
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read more about jaeger tracing:.
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https://www.jaegertracing.io/docs/
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JAEGER DEPLOYMENT
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-----------------
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there are couple of ways to deploy jaeger.
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it can be done using cephadm, or manually.
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please refer to:
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`Cephadm Jaeger services deployment <../cephadm/services/tracing/>`_
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`jaeger deployment <https://www.jaegertracing.io/docs/1.25/deployment/>`_
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`jaeger performance tuning <https://www.jaegertracing.io/docs/1.25/performance-tuning/>`_
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Important Notes:
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^^^^^^^^^^^^^^^^
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- Spans are being sent to local jaeger agent, so the jaeger agent must be running on each host (not in all-in-one mode). otherwise, spans of hosts without active jaeger agent will be lost.
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- Ceph tracers are configured to send tracers to agents that are listening to port 6799, so on manual jaeger deployment, option "--processor.jaeger-compact.server-host-port=6799" should be used.
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HOW TO ENABLE TRACING IN CEPH
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-----------------------------
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tracing in Ceph is disabled by default.
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it could be enabled globally, or for each entity separately (e.g. rgw).
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Enable tracing globally::
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$ ceph config set global jaeger_tracing_enable true
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Enable tracing for each entity::
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$ ceph config set <entity> jaeger_tracing_enable true
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TRACES IN RGW
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-------------
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traces of RGW can be found under Service `rgw` in Jaeger Frontend.
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REQUESTS
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^^^^^^^^
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every user request is being traced. each trace contains tags for
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`Operation name`, `User id`, `Object name` and `Bucket name`.
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there is also `Upload id` tag for Multipart upload operations.
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request trace is named `<command> <transaction id>`.
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MULTIPART UPLOAD
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^^^^^^^^^^^^^^^^
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there is a trace, that consists a span for each request that made by that multipart upload, including all `Put Object` requests.
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multipart trace is named `multipart_upload <upload id>`.
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rgw service in Jaeger Frontend:
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.. image:: ./rgw_jaeger.png
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:width: 400
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osd service in Jaeger Frontend:
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.. image:: ./osd_jaeger.png
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:width: 400
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