feat: add high-level architecture document

This commit introduces a new architecture document that can be used to
guide the high-level design of the system. This also includes C4
diagrams for the context and container level views of the system.

Author: scotwells

.github/workflows/verify-generate.yaml

@@ -0,0 +1,30 @@
+name: "Verify Generated Code"
+on:
+  pull_request:
+
+jobs:
+  verify-generate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v6
+
+      - name: Set up Go
+        uses: actions/setup-go@v6
+        with:
+          go-version-file: 'go.mod'
+
+      - name: Install Task
+        uses: go-task/setup-task@v1
+        with:
+          version: 3.x
+
+      - name: Install dependencies
+        run: go mod download
+
+      - name: Run task generate
+        run: task generate
+
+      - name: Check for diffs
+        run: |
+          git diff --exit-code || (echo "❌ Generated code is out of sync. Please run 'task generate' and commit the changes." && exit 1)

README.md

@@ -6,3 +6,5 @@ cluster resources in real-time via audit log events consumed from NATS
 JetStream, with declarative indexing policies controlling what gets indexed
 using CEL-based filtering. The service integrates natively with kubectl/RBAC and
 targets Meilisearch as the search backend.
+
+![](./docs/diagrams/SearchServiceContext.png)

Taskfile.yaml

@@ -1,5 +1,10 @@
 version: '3'
 
+includes:
+  docs:
+    taskfile: ./docs/Taskfile.yaml
+    dir: ./docs
+
 vars:
   TOOL_DIR: "{{.USER_WORKING_DIR}}/bin"
   IMAGE_NAME: "ghcr.io/datum-cloud/search"
@@ -72,6 +77,8 @@ tasks:
   # Code generation tasks
   generate:
     desc: Generate deepcopy and client code
+    deps:
+      - task: docs:generate
     cmds:
       - |
         set -e
@@ -116,3 +123,10 @@ tasks:
       - go vet ./...
       - echo "✅ Vet complete"
     silent: true
+
+  # Architecture diagram tasks
+  diagrams:
+    desc: Generate architecture diagrams from PlantUML
+    cmds:
+      - task: docs:diagrams
+    silent: true

docs/Taskfile.yaml

@@ -0,0 +1,68 @@
+version: '3'
+
+vars:
+  DIAGRAMS_DIR: "{{.USER_WORKING_DIR}}/docs/diagrams"
+  OUTPUT_FORMAT: "png"
+
+tasks:
+  generate:
+    desc: Generate all documentation artifacts (diagrams, etc.)
+    cmds:
+      - task: diagrams:render
+    silent: true
+
+  diagrams:
+    desc: Generate all architecture diagrams from PlantUML
+    cmds:
+      - task: diagrams:render
+    silent: true
+
+  diagrams:render:
+    desc: Render PlantUML diagrams to PNG format using Docker
+    cmds:
+      - |
+        set -e
+        echo "Rendering PlantUML diagrams..."
+        echo ""
+
+        # Check if PlantUML files exist
+        if [ ! -f "{{.DIAGRAMS_DIR}}/context.puml" ] || [ ! -f "{{.DIAGRAMS_DIR}}/container.puml" ]; then
+          echo "❌ Error: PlantUML source files not found in {{.DIAGRAMS_DIR}}"
+          exit 1
+        fi
+
+        # Render using Docker (no local installation required)
+        docker run --rm \
+          -v "{{.DIAGRAMS_DIR}}":/data \
+          plantuml/plantuml:latest \
+          -t{{.OUTPUT_FORMAT}} \
+          /data/*.puml
+
+        echo ""
+        echo "✅ Diagrams rendered in {{.DIAGRAMS_DIR}}"
+        echo ""
+        echo "Generated files:"
+        ls -1 {{.DIAGRAMS_DIR}}/*.{{.OUTPUT_FORMAT}} 2>/dev/null | xargs -n1 basename || echo "No output files found"
+    silent: true
+
+  diagrams:clean:
+    desc: Remove generated diagram files
+    cmds:
+      - |
+        rm -f {{.DIAGRAMS_DIR}}/*.png {{.DIAGRAMS_DIR}}/*.svg
+        echo "✅ Generated diagram files removed"
+    silent: true
+
+  diagrams:validate:
+    desc: Validate PlantUML syntax using Docker
+    cmds:
+      - |
+        set -e
+        echo "Validating PlantUML diagrams..."
+        docker run --rm \
+          -v "{{.DIAGRAMS_DIR}}":/data \
+          plantuml/plantuml:latest \
+          -syntax \
+          /data/*.puml
+        echo "✅ All diagrams are valid"
+    silent: true

docs/architecture.md

@@ -1,3 +1,75 @@
-# Architecture
+# Search Architecture
 
-TODO: Document service architecture
+## Overview
+
+The Search service is a Kubernetes-native API built on the aggregated
+API server framework that provides advanced resource discovery capabilities
+through field filtering and full-text search. It enables platform users to
+efficiently query and locate resources across the cluster using powerful
+indexing and real-time event processing.
+
+## Architecture Diagram
+
+> [!NOTE]
+>
+> Below is a [C4 container diagram][c4] of the service and it's dependencies.
+> This is meant to model individual components in the system and their
+> responsibilities. It does not aim to provide visibility into external system
+> components that may be a dependency of this system.
+
+<p align="center">
+  <img src="./diagrams/SearchServiceContainers.png" alt="Search service component software architecture diagram">
+</p>
+
+[c4]: https://c4model.com
+
+## Components
+
+### Search API Server
+
+**Purpose**: Expose search capabilities as native Kubernetes APIs
+
+**Responsibilities**:
+- Register custom API endpoints under `search.miloapis.com/v1alpha1`
+- Handle authentication and authorization via Kubernetes RBAC
+- Provide RESTful API for search queries
+- Manage custom resource definitions for the search service
+
+**Query Types**:
+- **Field Filtering**: Exact match, prefix, range queries on structured fields
+- **Full-Text Search**: Fuzzy matching, phrase queries, relevance scoring
+
+### Resource Indexer
+
+**Purpose**: Real-time indexing of platform resources from audit logs
+
+**Responsibilities**:
+- Subscribe to NATS JetStream audit log topic
+- Filter events based on active index policies
+- Evaluate CEL expressions for conditional indexing
+- Extract and transform resource data for indexing
+- Write to index backend with proper error handling and retries
+- Manage index lifecycle (creation, updates, deletion)
+- Bootstrap indexes from existing state
+
+### Controller Manager
+
+**Purpose**: Manages and validates resources for the search service
+
+**Responsibilities**:
+- Validates and activates index policies
+
+### Index Backend Storage
+
+**Purpose**: High-performance full-text search and indexing
+
+**Responsibilities**:
+- Structured metadata (namespace, name, labels, annotations) filtering
+- Full-text searchable content
+
+> [!NOTE]
+>
+> We're targeting [Meilisearch] as our first integration backend for indexed
+> storage.
+
+[Meilisearch]: https://www.meilisearch.com

docs/diagrams/SearchServiceContainers.png

@@ -0,0 +1,26 @@
+@startuml SearchServiceContainers
+!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml
+
+Person(platformUser, "Platform User", "An operator who needs to query and locate platform resources")
+
+System_Ext(platformAPI, "Platform API", "Manages cluster resources and provides aggregation layer for custom APIs")
+System_Ext(eventBus, "Event Streaming", "Event stream of audit logs collected from the apiserver")
+
+System_Boundary(searchService, "Search Service") {
+    Container(searchAPI, "Search APIServer", "Go, Kubernetes API Server Framework", "Provides a platform native API for searching resources")
+    Container(indexerService, "Resource Indexer", "Go", "Indexes platform resources based on index policies")
+    Container(controllerManager, "Controller Manager", "Go, Kubernetes Controller", "Manages index policies in the search service")
+    System(indexBackend, "Index Backend Storage", "High-performance full-text search engine for indexed resources")
+}
+
+Rel_D(platformUser, searchAPI, "Submits search queries and manages index policies", "HTTPS/JSON/UI")
+Rel(searchAPI, indexBackend, "Executes search queries", "HTTPS/JSON")
+Rel_L(controllerManager, searchAPI, "Watches search resources", "HTTPS/Watch API")
+
+Rel_L(indexerService, eventBus, "Consumes events from", "NATS Protocol")
+Rel_U(indexerService, searchAPI, "Retrieves index policies from", "HTTPS")
+Rel_D(platformAPI, eventBus, "Sends audit log events to", "HTTPS")
+Rel_R(indexerService, platformAPI, "Bootstraps indexes from resources in", "HTTPS")
+Rel_R(indexerService, indexBackend, "Writes indexed documents", "HTTPS/JSON")
+
+@enduml

docs/diagrams/SearchServiceContext.png

@@ -0,0 +1,20 @@
+@startuml SearchServiceContext
+!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Context.puml
+
+left to right direction
+
+Person(platformUser, "Platform User", "An operator who needs to query and locate platform resources")
+
+System(searchService, "Search Service", "Provides advanced resource discovery through field filtering and full-text search of platform resources")
+
+System_Ext(platformAPI, "Platform API", "Manages core resources, authn, authz, and provides aggregation layer for custom APIs")
+System_Ext(eventStream, "Event Streaming System", "Streams audit log events from the platform API")
+
+Rel_R(platformUser, searchService, "Searches resources using CLI, UI, or API clients", "HTTPS/JSON")
+Rel(platformUser, platformAPI, "Manages platform resources", "kubectl/HTTPS")
+
+Rel_D(searchService, platformAPI, "Indexes resources from", "HTTPS")
+Rel(searchService, eventStream, "Subscribes to audit log events", "NATS Protocol")
+Rel(platformAPI, eventStream, "Publishes audit logs to")
+
+@enduml