From 5dd38b7f18ae9b15a66bc81621665d99471d74a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adam=20=C5=A0trauch?= <cx@initd.cz>
Date: Thu, 19 Dec 2024 21:10:34 +0100
Subject: [PATCH] Prometheus service discovery

---
 .vscode/launch.json |  2 +-
 api/main.go         | 36 ++++++++++++++++++++++++++++++++++++
 api/types.go        |  5 +++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/.vscode/launch.json b/.vscode/launch.json
index acea204..6bf7ab0 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -29,7 +29,7 @@
             "env": {
                 "DUMP_PATH": "../tmp/nodes.json",
                 "CONFIG_PATH": "../tmp/config.json",
-                "NODE_DIR_PATH": "../tmp/node"
+                "NODE_PATH": "../tmp/node"
             },
             "args": [
                 "node"
diff --git a/api/main.go b/api/main.go
index a84f08f..2ad664e 100644
--- a/api/main.go
+++ b/api/main.go
@@ -3,6 +3,7 @@ package api
 import (
 	"log"
 	"net/http"
+	"strings"
 
 	_ "gitea.ceperka.net/rosti/lobby2/docs" // This line is necessary for swag to find your docs!
 	"gitea.ceperka.net/rosti/lobby2/nodes"
@@ -53,6 +54,7 @@ func (a *API) Run() error {
 	a.e.GET("/nodes", a.listHandler)
 	a.e.GET("/nodes/:hostname", a.getHandler)
 	a.e.POST("/nodes/:hostname", a.refreshHandler)
+	a.e.GET("/prometheus/:service", a.prometheusHandler)
 
 	// Start the server in a goroutine so that it doesn't block the signal listening
 	return a.e.Start(a.listen)
@@ -111,3 +113,37 @@ func (a *API) refreshHandler(c echo.Context) error {
 
 	return c.NoContent(http.StatusNoContent)
 }
+
+// @Summary Prometheus service discovery
+// @Description Return one nodes based on given hostname
+// @Produce  application/json
+// @Success 200 {array} []prometheusDiscovery "Node details"
+// @Failure 401 {object} Message "Forbidden access"
+// @Security Bearer
+// @Router /nodes/{hostname} [get]
+func (a *API) prometheusHandler(c echo.Context) error {
+	ss := c.QueryParam("service")
+
+	ns := a.np.List()
+
+	pds := []prometheusDiscovery{
+		{
+			Labels:  nodes.Labels{},
+			Targets: []string{},
+		},
+	}
+
+	for _, node := range ns {
+		v, ok := node.KV["prometheus_exporters"]
+		if ok {
+			services := strings.Split(v, ",")
+			for _, service := range services {
+				if ss == service {
+					pds[0].Targets = append(pds[0].Targets, node.HostName)
+				}
+			}
+		}
+	}
+
+	return c.JSONPretty(http.StatusOK, pds, "  ")
+}
diff --git a/api/types.go b/api/types.go
index 42eb56d..3a3cfe3 100644
--- a/api/types.go
+++ b/api/types.go
@@ -10,3 +10,8 @@ type params struct {
 	Labels nodes.Labels `json:"labels"`
 	KV     nodes.KV     `json:"kv"`
 }
+
+type prometheusDiscovery struct {
+	Labels  nodes.Labels `json:"labels"`
+	Targets []string     `json:"targets"`
+}