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.

Running the Sandbox

The following documentation runs through the setup of an Envoy cluster organized as is described in the image above.

Step 1: Install Docker

Ensure that you have a recent version of docker and docker-compose installed.

A simple way to achieve this is via the Docker Desktop.

Step 2: Clone the Envoy repo, and start all of our containers

If you have not cloned the Envoy repo, clone it with git clone git@github.com:envoyproxy/envoy or git clone https://github.com/envoyproxy/envoy.git

Terminal 1

  1. $ pwd
  2. envoy/examples/load_reporting_service
  3. $ docker-compose pull
  4. $ docker-compose up --scale http_service=2

Terminal 2

  1. $ pwd
  2. envoy/examples/load_reporting_service
  3. $ docker-compose ps
  5.                             Name                               Command               State                           Ports
  6. --------------------------------------------------------------------------------------------------------------------------------------
  7. load-reporting-service_http_service_1   /bin/sh -c /usr/local/bin/ ... Up      10000/tcp, 0.0.0.0:80->80/tcp, 0.0.0.0:8081->8081/tcp
  8. load-reporting-service_http_service_2   /bin/sh -c /usr/local/bin/ ... Up      10000/tcp, 0.0.0.0:81->80/tcp, 0.0.0.0:8082->8081/tcp
  9. load-reporting-service_lrs_server_1     go run main.go                   Up      0.0.0.0:18000->18000/tcp

Step 3: Start sending stream of HTTP requests

Terminal 2

  1. $ pwd
  2. envoy/examples/load_reporting_service
  3. $ 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 4: See Envoy Stats

You should see

Terminal 1

  1. ............................
  2. lrs_server_1    | 2020/02/12 17:08:20 LRS Server is up and running on :18000
  3. lrs_server_1    | 2020/02/12 17:08:23 Adding new cluster to cache `http_service` with node `0022a319e1e2`
  4. lrs_server_1    | 2020/02/12 17:08:24 Adding new node `2417806c9d9a` to existing cluster `http_service`
  5. lrs_server_1    | 2020/02/12 17:08:25 Creating LRS response for cluster http_service, node 2417806c9d9a with frequency 2 secs
  6. lrs_server_1    | 2020/02/12 17:08:25 Creating LRS response for cluster http_service, node 0022a319e1e2 with frequency 2 secs
  7. http_service_2  | 127.0.0.1 - - [12/Feb/2020 17:09:06] "GET /service HTTP/1.1" 200 -
  8. http_service_1  | 127.0.0.1 - - [12/Feb/2020 17:09:06] "GET /service HTTP/1.1" 200 -
  9. ............................
  10. 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 >
  11. 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 >
  12. http_service_2  | 127.0.0.1 - - [12/Feb/2020 17:09:07] "GET /service HTTP/1.1" 200 -
  13. http_service_1  | 127.0.0.1 - - [12/Feb/2020 17:09:07] "GET /service HTTP/1.1" 200 -
  14. ............................
  15. 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 >
  16. 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 >