Load reporting service (LRS)
This simple example demonstrates Envoy’s Load reporting service (LRS) capability and how to use it.
Lets say Cluster A (downstream) talks to Cluster B (Upstream) and Cluster C (Upstream). When enabling Load Report for Cluster A, LRS server should be sending LoadStatsResponse to Cluster A with LoadStatsResponse.Clusters to be B and C. LRS server will then receive LoadStatsRequests (with total requests, successful requests etc) from Cluster A to Cluster B and from Cluster A to Cluster C.
In this example, all incoming requests are routed via Envoy to a simple goLang web server aka http_server. We scale up two containers and randomly send requests to each. Envoy is configured to initiate the connection with LRS Server. LRS Server enables the stats by sending LoadStatsResponse. Sending requests to http_server will be counted towards successful requests and will be visible in LRS Server logs.
Step 1: Build the sandbox
Change to the examples/load-reporting-service directory.
Terminal 1
$ pwd
envoy/examples/load-reporting-service
$ docker compose pull
$ docker compose up --scale http_service=2
Terminal 2
$ pwd
envoy/examples/load_reporting_service
$ docker compose ps
Name Command State Ports
-----------------------------------------------------------------------------------------------------------------
load-reporting-service_http_service_1 /docker-entrypoint.sh /usr ... Up 10000/tcp, 0.0.0.0:81->80/tcp
load-reporting-service_http_service_2 python3 /code/service.py ... Up (healthy)
load-reporting-service_lrs_server_1 go run main.go Up
Step 2: Start sending stream of HTTP requests
Terminal 2
$ pwd
envoy/examples/load_reporting_service
$ bash send_requests.sh
The script above (send_requests.sh) sends requests
randomly to each Envoy, which in turn forwards the requests to the backend service.
Step 3: See Envoy Stats
You should see
Terminal 1
............................
lrs_server_1 | 2020/02/12 17:08:20 LRS Server is up and running on :18000
lrs_server_1 | 2020/02/12 17:08:23 Adding new cluster to cache `http_service` with node `0022a319e1e2`
lrs_server_1 | 2020/02/12 17:08:24 Adding new node `2417806c9d9a` to existing cluster `http_service`
lrs_server_1 | 2020/02/12 17:08:25 Creating LRS response for cluster http_service, node 2417806c9d9a with frequency 2 secs
lrs_server_1 | 2020/02/12 17:08:25 Creating LRS response for cluster http_service, node 0022a319e1e2 with frequency 2 secs
http_service_2 | 127.0.0.1 - - [12/Feb/2020 17:09:06] "GET /service HTTP/1.1" 200 -
http_service_1 | 127.0.0.1 - - [12/Feb/2020 17:09:06] "GET /service HTTP/1.1" 200 -
............................
lrs_server_1 | 2020/02/12 17:09:07 Got stats from cluster `http_service` node `0022a319e1e2` - cluster_name:"local_service" upstream_locality_stats:<locality:<> total_successful_requests:21 total_issued_requests:21 > load_report_interval:<seconds:1 nanos:998411000 >
lrs_server_1 | 2020/02/12 17:09:07 Got stats from cluster `http_service` node `2417806c9d9a` - cluster_name:"local_service" upstream_locality_stats:<locality:<> total_successful_requests:17 total_issued_requests:17 > load_report_interval:<seconds:1 nanos:994529000 >
http_service_2 | 127.0.0.1 - - [12/Feb/2020 17:09:07] "GET /service HTTP/1.1" 200 -
http_service_1 | 127.0.0.1 - - [12/Feb/2020 17:09:07] "GET /service HTTP/1.1" 200 -
............................
lrs_server_1 | 2020/02/12 17:09:09 Got stats from cluster `http_service` node `0022a319e1e2` - cluster_name:"local_service" upstream_locality_stats:<locality:<> total_successful_requests:3 total_issued_requests:3 > load_report_interval:<seconds:2 nanos:2458000 >
lrs_server_1 | 2020/02/12 17:09:09 Got stats from cluster `http_service` node `2417806c9d9a` - cluster_name:"local_service" upstream_locality_stats:<locality:<> total_successful_requests:9 total_issued_requests:9 > load_report_interval:<seconds:2 nanos:6487000 >
See also
- Load reporting service
Overview of Envoy’s Load reporting service.
- Load reporting service API(V3)
The Load reporting service API.