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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+..
+
+======================================
+fluentbit-fluentd logging architecture
+======================================
+
+Blueprints:
+1. osh-logging-framework_
+
+.. _osh-logging-framework: https://blueprints.launchpad.net/openstack-helm/+spec/osh-logging-framework
+
+Releated Specs:
+1. OSH logging monitoring and alerting: https://review.openstack.org/#/c/482687/
+
+
+Problem Description
+===================
+
+OpenStack-Helm defines a centralized logging mechanism to provide insight into
+the the state of the OpenStack services and infrastructure components as
+well as underlying Kubernetes platform. Among the requirements for a logging
+platform, where log data can come from and where log data need to be delivered
+are very variable. To support various logging scenarios, OpenStack-Helm should
+provide a flexible mechanism to meet with certain operation needs. This spec
+proposes fast and lightweight log forwarder and full featured log aggregator
+complementing each other providing a flexible and reliable solution. Especially,
+Fluentbit is proposed as a log forwarder and Fluentd is proposed as a main log
+aggregator and processor.
+
+Platform Requirements
+=====================
+
+Logging Requirements
+--------------------
+
+The requirements for a logging collector/aggregator include:
+
+1. Log collection daemon runs on each node to forward logs to aggregator
+2. Log collection daemon should have a minimal server footprint
+3. Log aggregator deployment runs on a selected node as deployment
+4. Ability to apply custom metadata and uniform format to logs
+5. Log aggregator should have HA capability
+6. Log aggregator should have a flexible output capability to choose from
+7. Log aggregator is able to send data to Elasticsearch and Kafka
+8. Log aggregator should be scalable
+
+Logical Diagram
+---------------
+
+1. diagram link: https://github.com/sktelecom-oslab/docs/blob/master/images/fluentbit-fluentd-diagram.png
+
+Use Cases
+=========
+
+Logging Use Cases
+-----------------
+
+Example uses for centralized logging with Fluentbit and Fluentd include:
+
+1. Cover the following logging use cases https://review.openstack.org/#/c/482687/
+2. Collect logs from the node by Fluentbit
+3. Every Fluentbit send logs to Fluentd with Kubernetes metadata attached
+4. Fluentd then attaches Kubernetes and/or OpenStack metadata
+5. Fluentd properly filters and categorizes logs
+6. Fluentd send aggregated logs to Elasticsearch for the internal use cases
+7. Aggregator also send aggregated logs to Kafka for external tools to consume
+
+
+Proposed Change
+===============
+
+Logging
+-------
+
+Fluentbit, Fluentd meet OpenStack-Helm's logging requirements for gathering,
+aggregating, and delivering of logged events. Fluntbit runs as a daemonset on
+each node and mounts the /var/lib/docker/containers directory. The Docker
+container runtime engine directs events posted to stdout and stderr to this
+directory on the host. Fluentbit then forward the contents of that directory to
+Fluentd. Fluentd runs as deployment at the designated nodes and expose service
+for Fluentbit to foward logs. Fluentd should then apply the Logstash format to
+the logs. Fluentd can also write Kubernetes and OpenStack metadata to the logs.
+Fluentd will then forward the results to Elasticsearch and to optionally Kafka.
+Elasticsearch indexes the logs in a logstash-* index by default. Kafka stores
+the logs in a 'logs' topic by default. Any external tool can then consume the
+'logs' topic.
+
+The proposal includes the following:
+
+1. Helm chart for Fluentbit-Fluentd Combination
+
+The above chart must include sensible configuration values to make the logging
+platform usable by default. These include: proper input configurations for both
+Fluentbit and Fluentd, proper output configurations for both Fluentbit and
+Fluentd, proper metadata and formats applied to the logs via Fluentd.
+
+
+Security Impact
+---------------
+
+All services running within the platform should be subject to the
+security practices applied to the other OpenStack-Helm charts.
+
+Performance Impact
+------------------
+
+To minimize the performance impacts, the following should be considered:
+
+1. Sane defaults for log retention and rotation policies
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignees:
+  sungil (Sungil Im)
+  jayahn (Jaesuk Ahn)
+
+Work Items
+----------
+
+1. Fluentbit-Fluentd logging chart
+
+All charts should follow design approaches applied to all other OpenStack-Helm
+charts, including the use of helm-toolkit.
+
+All charts require valid and sensible default values to provide operational
+value out of the box.
+
+Testing
+=======
+Testing should include Helm tests for each of the included charts as well as an
+integration test in the gate.
+
+
+Documentation Impact
+====================
+Documentation should be included for each of the included charts as well as
+documentation detailing the requirements for a usable monitoring platform,
+preferably with sane default values out of the box.
diff --git a/doc/source/specs/index.rst b/doc/source/specs/index.rst
index 7b07a561d5..3651f16eb7 100644
--- a/doc/source/specs/index.rst
+++ b/doc/source/specs/index.rst
@@ -11,3 +11,4 @@ Contents:
    template.rst
    neutron-multiple-sdns.rst
    support-linux-bridge-on-neutron.rst
+   fluentbit-fluentd-architecture.rst