From 094e23f7369d95d968cbfd9671dbcd3d6ee1626e Mon Sep 17 00:00:00 2001
From: Ken Hibino <ken.hibino7@gmail.com>
Date: Sun, 3 Jan 2021 06:56:53 -0800
Subject: [PATCH] Add API endpoint to fetch redis info

---
 go.mod                 |  2 +-
 go.sum                 |  1 +
 main.go                |  9 +++++++++
 redis_info_handlers.go | 46 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 redis_info_handlers.go

diff --git a/go.mod b/go.mod
index 52ccf1d..2128743 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module asynqmon
 go 1.14
 
 require (
-	github.com/go-redis/redis/v8 v8.4.4 // indirect
+	github.com/go-redis/redis/v8 v8.4.4
 	github.com/gorilla/mux v1.8.0
 	github.com/hibiken/asynq v0.13.1
 	github.com/rs/cors v1.7.0
diff --git a/go.sum b/go.sum
index 482cf69..b6a48e1 100644
--- a/go.sum
+++ b/go.sum
@@ -74,6 +74,7 @@ golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e h1:9vRrk9YW2BTzLP0VCB9ZDjU4c
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200519105757-fe76b779f299/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f h1:+Nyd8tzPX9R7BWHguqsrbFdRx3WQ/1ib8I44HXV5yTA=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
diff --git a/main.go b/main.go
index a192d1a..10fb204 100644
--- a/main.go
+++ b/main.go
@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"time"
 
+	"github.com/go-redis/redis/v8"
 	"github.com/gorilla/mux"
 	"github.com/hibiken/asynq"
 	"github.com/rs/cors"
@@ -64,6 +65,11 @@ func main() {
 	})
 	defer inspector.Close()
 
+	rdb := redis.NewClient(&redis.Options{
+		Addr: "localhost:6379",
+	})
+	defer rdb.Close()
+
 	router := mux.NewRouter()
 	router.Use(loggingMiddleware)
 
@@ -119,6 +125,9 @@ func main() {
 	api.HandleFunc("/scheduler_entries", newListSchedulerEntriesHandlerFunc(inspector)).Methods("GET")
 	api.HandleFunc("/scheduler_entries/{entry_id}/enqueue_events", newListSchedulerEnqueueEventsHandlerFunc(inspector)).Methods("GET")
 
+	// Redis info endpoint.
+	api.HandleFunc("/redis_info", newRedisInfoHandlerFunc(rdb)).Methods("GET")
+
 	fs := &staticFileServer{staticPath: "ui/build", indexPath: "index.html"}
 	router.PathPrefix("/").Handler(fs)
 
diff --git a/redis_info_handlers.go b/redis_info_handlers.go
new file mode 100644
index 0000000..c32138a
--- /dev/null
+++ b/redis_info_handlers.go
@@ -0,0 +1,46 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"strings"
+
+	"github.com/go-redis/redis/v8"
+)
+
+// ****************************************************************************
+// This file defines:
+//   - http.Handler(s) for redis info related endpoints
+// ****************************************************************************
+
+func newRedisInfoHandlerFunc(rdb *redis.Client) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ctx := context.Background()
+		res, err := rdb.Info(ctx).Result()
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		info := parseRedisInfo(res)
+		if err := json.NewEncoder(w).Encode(info); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+	}
+}
+
+// Parses the return value from the INFO command.
+// See https://redis.io/commands/info#return-value.
+func parseRedisInfo(infoStr string) map[string]string {
+	info := make(map[string]string)
+	lines := strings.Split(infoStr, "\r\n")
+	for _, l := range lines {
+		kv := strings.Split(l, ":")
+		if len(kv) == 2 {
+			info[kv[0]] = kv[1]
+		}
+	}
+	return info
+
+}