test build

local/go-ucs/api/example_rate_limiter_test.go

@@ -0,0 +1,88 @@
+package api_test
+
+import (
+	"context"
+	"crypto/tls"
+	"log"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/dnaeon/go-ucs/api"
+	"github.com/dnaeon/go-ucs/mo"
+)
+
+func Example_rateLimiter() {
+	// The following example shows how to rate limit requests again the remote
+	// Cisco UCS API endpoint using a token bucket rate limiter.
+	// https://en.wikipedia.org/wiki/Token_bucket
+
+	// Skip SSL certificate verification of remote endpoint.
+	tr := &http.Transport{
+		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+	}
+	httpClient := &http.Client{Transport: tr}
+
+	// Create a new Cisco UCS API client.
+	// Set maximum allowed requests per second to 1 with a burst size of 1.
+	// A request will wait up to 1 minute for a token.
+	config := api.Config{
+		Endpoint:   "https://ucs01.example.org/",
+		Username:   "admin",
+		Password:   "password",
+		HttpClient: httpClient,
+		RateLimit: &api.RateLimit{
+			RequestsPerSecond: 1.0,
+			Burst:             1,
+			Wait:              time.Duration(1 * time.Minute),
+		},
+	}
+
+	client, err := api.NewClient(config)
+	if err != nil {
+		log.Fatalf("Unable to create API client: %s", err)
+	}
+
+	ctx := context.Background()
+
+	log.Printf("Logging in to %s\n", config.Endpoint)
+	if _, err := client.AaaLogin(ctx); err != nil {
+		log.Fatalf("Unable to login: %s\n", err)
+	}
+	defer client.AaaLogout(ctx)
+
+	log.Printf("Got authentication cookie: %s\n", client.Cookie)
+
+	// Start a few concurrent requests to the remote API endpoint.
+	// Requests will be executed one at a time, because of how the limiter is configured.
+	var wg sync.WaitGroup
+	for i := 1; i < 10; i++ {
+		wg.Add(1)
+
+		// Our worker function will retrieve the `sys` DN from the remote Cisco UCS API.
+		// We will start a few of these in separate goroutines.
+		worker := func(id int) {
+			defer wg.Done()
+
+			// Retrieve the `sys` DN, which is of type mo.TopSystem
+			log.Printf("Worker #%d: Retrieving `sys` managed object\n", id)
+			req := api.ConfigResolveDnRequest{
+				Cookie:         client.Cookie,
+				Dn:             "sys",
+				InHierarchical: "false",
+			}
+
+			var sys mo.TopSystem
+			if err := client.ConfigResolveDn(ctx, req, &sys); err != nil {
+				log.Printf("Worker #%d: Unable to retrieve DN: %s\n", id, err)
+				return
+			}
+
+			log.Printf("Worker #%d: successfully retrieved `sys` managed object\n", id)
+		}
+
+		go worker(i)
+	}
+
+	wg.Wait()
+}