feat: add design.md

apps/metrics/docs/design.md

@@ -0,0 +1,146 @@
+# 1.Override
+
+We support two ways to query metrics:
+- Connect to StarRocks data warehouse and query metrics from it
+- Query Prometheus directly and retrieve metrics from it
+
+# 2.Starrocks Metric
+
+We can implement StarRocks Metric queries similar to Prometheus Metric queries. The only difference is replacing PromQL with SQL and querying through StarRocks API.
+
+# 3.Prometheus Metric
+
+## 3.1.Metrics Config
+Currently, metrics are configured in code. In the future, they will be configured through database or other methods.
+Organization structure: Product ID -> Metric Name -> Metric Query Method (PromQL)
+```json
+{
+  "freeleaps": {
+    // Just for demo
+    "cpu_usage": "100 - (avg by (instance) (irate(node_cpu_seconds_total{mode=\"idle\"}[5m])) * 100)",
+    // Just for demo
+    "memory_usage": "100 - ((node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes) * 100)",
+    // Just for demo
+    "disk_usage": "100 - ((node_filesystem_avail_bytes{mountpoint=\"/\"} / node_filesystem_size_bytes{mountpoint=\"/\"}) * 100)",
+    "latency_ms": "1000*avg(freeleaps_notification_http_request_duration_seconds_sum{handler!=\"none\"} / freeleaps_notification_http_request_duration_seconds_count)",
+    "reliability": "1-sum(rate(freeleaps_notification_http_requests_total{status=\"5xx\"}[1m]))"
+  },
+  "magicleaps": {}
+}
+```
+If we want to add new metrics, theoretically we only need to add one configuration entry (provided that the metric exists in Prometheus and can be queried directly through PromQL without requiring any additional code processing)
+
+## 3.2.API Design
+
+### 3.2.1.Query Metrics by Product ID
+
+API: `/api/metrics/prometheus/product/{product_id}/available-metrics`
+
+Method: GET
+Request:
+```
+product_id=freeleaps
+```
+Response:
+
+```json
+{
+  "product_id": "freeleaps",
+  "available_metrics": [
+    "cpu_usage",
+    "memory_usage",
+    "disk_usage",
+    "latency_ms",
+    "reliability"
+  ],
+  "total_count": 5,
+  "description": "List of metrics with predefined PromQL queries for product 'freeleaps'"
+}
+```
+
+### 3.2.2.Query Metric Info
+API: `/api/metrics/prometheus/product/{product_id}/metric/{metric_name}/info`
+
+Method: GET
+Request:
+```
+product_id=freeleaps
+metric_name=cpu_usage
+```
+Response:
+
+```json
+{
+  "metric_info": {
+    "product_id": "freeleaps",
+    "metric_name": "cpu_usage",
+    "promql_query": "100 - (avg by (instance) (irate(node_cpu_seconds_total{mode=\"idle\"}[5m])) * 100)",
+    "description": "PromQL query for cpu_usage metric in product freeleaps"
+  },
+  "description": "Information about metric 'cpu_usage' in product 'freeleaps'"
+}
+```
+
+### 3.2.3.Query Metric Data
+API: `/api/metrics/prometheus/metrics_query`
+
+Method: GET
+Request:
+```
+{
+    "product_id":"freeleaps",
+    "metric_name": "latency_ms",
+    "start_time": "2025-09-12T00:00:00Z",
+    "end_time": "2025-09-16T01:00:00Z",
+    "step":"1h" # Interval between data points in the query result
+}
+```
+Response:
+
+```json
+{
+  "metric_name": "latency_ms",
+  "data_points": [
+    {
+      "date": "2025-09-12T08:00:00Z",
+      "value": 41.37141507698155,
+      "labels": {} # Optional: Additional labels for prometheus, Just for debugging
+    },
+    {
+      "date": "2025-09-12T09:00:00Z",
+      "value": 41.371992733188385,
+      "labels": {}
+    },
+    {
+      "date": "2025-09-12T10:00:00Z",
+      "value": 41.37792878125675,
+      "labels": {}
+    },
+    {
+      "date": "2025-09-12T11:00:00Z",
+      "value": 41.37297490632533,
+      "labels": {}
+    },
+    ...
+    {
+      "date": "2025-09-16T08:00:00Z",
+      "value": 40.72491916149973,
+      "labels": {}
+    },
+    {
+      "date": "2025-09-16T09:00:00Z",
+      "value": 40.72186597550194,
+      "labels": {}
+    }
+  ],
+  "total_points": 98,
+  "time_range": {
+    "start": "2025-09-12T00:00:00Z",
+    "end": "2025-09-16T01:00:00Z"
+  },
+  "step": "1h"
+}
+```
+
+# 4.Universal Metrics
+In the future, we can create an abstraction layer above StarRocks Metrics and Prometheus Metrics to unify metric queries from both data sources!