[RFC] Stage 0 - TSDB Dimensions

rfcs/0000-tsdb-dimensions.md

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+# 0000: TSDB Dimensions
+<!-- Leave this ID at 0000. The ECS team will assign a unique, contiguous RFC number upon merging the initial stage of this RFC. -->
+
+- Stage: **0 (strawperson)** <!-- Update to reflect target stage. See https://elastic.github.io/ecs/stages.html -->
+- Date: **TBD** <!-- The ECS team sets this date at merge time. This is the date of the latest stage advancement. -->
+
+<!--
+As you work on your RFC, use the "Stage N" comments to guide you in what you should focus on, for the stage you're targeting.
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+<!--
+Stage 0: Provide a high level summary of the premise of these changes. Briefly describe the nature, purpose, and impact of the changes. ~2-5 sentences.
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+
+<!--
+Stage 1: If the changes include field additions or modifications, please create a folder titled as the RFC number under rfcs/text/. This will be where proposed schema changes as standalone YAML files or extended example mappings and larger source documents will go as the RFC is iterated upon.
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+Stage X: Provide a brief explanation of why the proposal is being marked as abandoned. This is useful context for anyone revisiting this proposal or considering similar changes later on.
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+
+## Fields
+
+This RFC proposes the annotating of certain ecs fields as `dimension`. This change is proposed to take the advantage of using `TSDB` offered by the elasticsearch without impacting the data injection.  
+
+Annotating field as `dimension` is one of the important step in the process of TSDB adoption. Failing to annotate adequate number of fields as `dimension` when `TSDB` is enabled may lead to data loss. A large majority of fields that must be annotated as `dimension` fields are ecs fields. Presently, the Integration (Service Integration, Cloud Native, etc ) developers are expected to annotate ecs fields as `dimensions` in integration configuration. To avoid the duplicatation in configuration, minimize data loss probability, the RFC is proposed. `dimension` field takes two values - `true` and `false`.
+
+
+Changes to :service mapping
+
+```yaml
+---
+- name: service
+  title: Service
+  group: 2
+  short: Fields describing the service for or from which the data was collected.
+  description: >
+    The service fields describe the service for or from which the data was collected.
+
+    These fields help you find and correlate logs for a specific
+    service and version.
+  footnote: >
+    The service fields may be self-nested under service.origin.* and service.target.*
+    to describe origin or target services in the context of incoming or outgoing requests,
+    respectively.
+    However, the fieldsets service.origin.* and service.target.* must not be confused with
+    the root service fieldset that is used to describe the actual service under observation.
+    The fieldset service.origin.* may only be used in the context of incoming requests or
+    events to describe the originating service of the request. The fieldset service.target.*
+    may only be used in the context of outgoing requests or events to describe the target
+    service of the request.
+  reusable:
+    top_level: true
+    expected:
+      - at: service
+        as: origin
+        beta: Reusing the `service` fields in this location is currently considered beta.
+        short_override: Describes the origin service in case of an incoming request or event.
+      - at: service
+        as: target
+        beta: Reusing the `service` fields in this location is currently considered beta.
+        short_override: Describes the target service in case of an outgoing request or event.
+  type: group
+  fields:
+
+    - name: address
+      level: extended
+      type: keyword
+      dimension: true
+      short: Address of this service.
+      description: >
+        Address where data about this service was collected from.
+
+        This should be a URI, network address (ipv4:port or [ipv6]:port) or a resource path (sockets).
+      example: 172.26.0.2:5432
+
+```
+Changes to host mapping
+
+```yaml
+---
+- name: host
+  title: Host
+  group: 2
+  short: Fields describing the relevant computing instance.
+  description: >
+    A host is defined as a general computing instance.
+
+    ECS host.* fields should be populated with details about the host on which
+    the event happened, or from which the measurement was taken.
+    Host types include hardware, virtual machines, Docker containers, and Kubernetes nodes.
+  type: group
+  fields:
+    - name: hostname
+      level: core
+      type: keyword
+      short: Hostname of the host.
+      dimension: true
+      description: >
+        Hostname of the host.
+
+        It normally contains what the `hostname` command returns on the host machine.
+
+```
+Changes to host mapping
+
+```yaml
+---
+- name: agent
+  title: Agent
+  group: 2
+  short: Fields about the monitoring agent.
+  description: >
+    The agent fields contain the data about the software entity, if any, that collects, detects, or observes events on a host, or takes measurements on a host.
+
+    Examples include Beats. Agents may also run on observers. ECS agent.* fields shall be populated with details of the agent running on the host or observer where the event happened or the measurement was taken.
+  footnote: >
+    Examples: In the case of Beats for logs, the agent.name is filebeat. For APM, it is the
+    agent running in the app/service. The agent information does not change if
+    data is sent through queuing systems like Kafka, Redis, or processing systems
+    such as Logstash or APM Server.
+  type: group
+  fields:
+
+    - name: id
+      level: core
+      type: keyword
+      short: Unique identifier of this agent.
+      description: >
+        Unique identifier of this agent (if one exists).
+
+        Example: For Beats this would be beat.id.
+      example: 8a4f500d
+      dimension: true
+```
+<!--
+Stage 1: Describe at a high level how this change affects fields. Include new or updated yml field definitions for all of the essential fields in this draft. While not exhaustive, the fields documented here should be comprehensive enough to deeply evaluate the technical considerations of this change. The goal here is to validate the technical details for all essential fields and to provide a basis for adding experimental field definitions to the schema. Use GitHub code blocks with yml syntax formatting, and add them to the corresponding RFC folder.
+-->
+
+<!--
+Stage 2: Add or update all remaining field definitions. The list should now be exhaustive. The goal here is to validate the technical details of all remaining fields and to provide a basis for releasing these field definitions as beta in the schema. Use GitHub code blocks with yml syntax formatting, and add them to the corresponding RFC folder.
+-->
+
+## Usage
+
+<!--
+Stage 1: Describe at a high-level how these field changes will be used in practice. Real world examples are encouraged. The goal here is to understand how people would leverage these fields to gain insights or solve problems. ~1-3 paragraphs.
+-->
+
+Integration package development is the key beneficiary of this change. The fields of the document that are received from an integration receives a field mapping. If and when TSDB benefits are to be utilised, along with the field mapping with a metric type, at least one of the fields  must receive `dimension: true` annotation. 
+
+Example of field mapping in integrations with the field enabled as a dimension field.
+```yaml
+---
+- name: wait_class
+  type: keyword
+  description: Every wait event belongs to a class of wait event. 
+  dimension: true
+
+```
+## Source data
+
+The source of this data comes from monitoring a host like a Linux machine, laptop or a k8s node. The can come delivered through different shippers like Elastic Agent system metrics inputs, apm agents, prometheus node exporter and other host metric collectors.
+<!--
+Stage 1: Provide a high-level description of example sources of data. This does not yet need to be a concrete example of a source document, but instead can simply describe a potential source (e.g. nginx access log). This will ultimately be fleshed out to include literal source examples in a future stage. The goal here is to identify practical sources for these fields in the real world. ~1-3 sentences or unordered list.
+-->
+
+<!--
+Stage 2: Included a real world example source document. Ideally this example comes from the source(s) identified in stage 1. If not, it should replace them. The goal here is to validate the utility of these field changes in the context of a real world example. Format with the source name as a ### header and the example document in a GitHub code block with json formatting, or if on the larger side, add them to the corresponding RFC folder.
+-->
+
+<!--
+Stage 3: Add more real world example source documents so we have at least 2 total, but ideally 3. Format as described in stage 2.
+-->
+
+## Scope of impact
+
+<!--
+Stage 2: Identifies scope of impact of changes. Are breaking changes required? Should deprecation strategies be adopted? Will significant refactoring be involved? Break the impact down into:
+ * Ingestion mechanisms (e.g. beats/logstash)
+ * Usage mechanisms (e.g. Kibana applications, detections)
+ * ECS project (e.g. docs, tooling)
+The goal here is to research and understand the impact of these changes on users in the community and development teams across Elastic. 2-5 sentences each.
+-->
+
+## Concerns
+
+No concerns are known as of now. Presence of the `dimension:true` does not impact functionality. Elastic Stack version 8.7 is essential for this. 
+<!--
+Stage 1: Identify potential concerns, implementation challenges, or complexity. Spend some time on this. Play devil's advocate. Try to identify the sort of non-obvious challenges that tend to surface later. The goal here is to surface risks early, allow everyone the time to work through them, and ultimately document resolution for posterity's sake.
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+Stage 3: Document resolutions for all existing concerns. Any new concerns should be documented along with their resolution. The goal here is to eliminate risk of churn and instability by ensuring all concerns have been addressed.
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+
+## People
+
+The following are the people that consulted on the contents of this RFC.
+
+* @agithomas | author
+* @ruflin | subject matter expert
+* @lalit-satapathy | reviewer
+* @martijnvg | reviewer
+<!--
+Who will be or has been consulted on the contents of this RFC? Identify authorship and sponsorship, and optionally identify the nature of involvement of others. Link to GitHub aliases where possible. This list will likely change or grow stage after stage.
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+
+
+## References
+
+* [TSDB Design Document](https://github.com/elastic/elasticsearch-adrs/blob/master/analytics/tsdb/tsdb-design.md)
+* [Oracle Package Pull Request for TSDB Migraiton](https://github.com/elastic/integrations/pull/4966)
+
+<!-- Insert any links appropriate to this RFC in this section. -->
+
+### RFC Pull Requests
+
+<!-- An RFC should link to the PRs for each of it stage advancements. -->
+
+* Stage 0: https://github.com/elastic/ecs/pull/1386
+
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+* Stage 1: https://github.com/elastic/ecs/pull/NNN
+...
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