Add longevity test results for 1.2.0 (nginx#1737)

Problem

Ensure 1.2.0 NGF runs without errors over long period of time and
doesn't introduce any memory leaks.

Solution:

- Run longevity tests for 1.2.0
-Share the results.

CLOSES -- nginx#1647

Author: miledxz

tests/results/longevity/1.2.0/1.2.0.md

@@ -0,0 +1,238 @@
+# Results
+
+Note: product telemetry feature was enabled but sending of product telemetry data was disabled.
+
+## NGINX OSS
+
+### Test environment
+
+NGINX Plus: false
+
+GKE Cluster:
+
+- Node count: 3
+- k8s version: v1.27.8-gke.1067004
+- vCPUs per node: 2
+- RAM per node: 4022900Ki
+- Max pods per node: 110
+- Zone: us-central1-c
+- Instance Type: e2-medium
+
+NGF pod name -- ngf-longevity-nginx-gateway-fabric-7f596f74c5-xzkzb
+
+### Traffic
+
+HTTP:
+
+```text
+Running 5760m test @ http://cafe.example.com/coffee
+  2 threads and 100 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   183.83ms  143.49ms   2.00s    79.14%
+    Req/Sec   303.07    204.23     2.22k    66.90%
+  204934013 requests in 5760.00m, 71.25GB read
+  Socket errors: connect 0, read 344459, write 0, timeout 5764
+Requests/sec:    592.98
+Transfer/sec:    216.19KB
+```
+
+HTTPS:
+
+```text
+Running 5760m test @ https://cafe.example.com/tea
+  2 threads and 100 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   175.23ms  122.10ms   2.00s    68.72%
+    Req/Sec   301.92    203.60     1.95k    66.97%
+  204120642 requests in 5760.00m, 69.83GB read
+  Socket errors: connect 0, read 337203, write 0, timeout 246
+Requests/sec:    590.63
+Transfer/sec:    211.87KB
+```
+
+### Logs
+
+No error logs in nginx-gateway
+
+No error logs in nginx
+
+### Key Metrics
+
+#### Containers memory
+
+![oss-memory.png](oss-memory.png)
+
+Drop in NGINX memory usage corresponds to the end of traffic generation.
+
+#### NGF Container Memory
+
+![oss-ngf-memory.png](oss-ngf-memory.png)
+
+### Containers CPU
+
+![oss-cpu.png](oss-cpu.png)
+
+Drop in NGINX CPU usage corresponds to the end of traffic generation.
+
+### NGINX metrics
+
+![oss-stub-status.png](oss-stub-status.png)
+
+Drop in request corresponds to the end of traffic generation.
+
+
+### Reloads
+
+Rate of reloads - successful and errors:
+
+![oss-reloads.png](oss-reloads.png)
+
+
+Reload spikes correspond to 1 hour periods of backend re-rollouts.
+However, small spikes, correspond to periodic reconciliation of Secrets, which (incorrectly)
+triggers a reload -- https://github.com/nginxinc/nginx-gateway-fabric/issues/1112
+
+No reloads finished with an error.
+
+Reload time distribution - counts:
+
+![oss-reload-time.png](oss-reload-time.png)
+
+
+Reload related metrics at the end:
+
+![oss-final-reloads.png](oss-final-reloads.png)
+
+All successful reloads took less than 5 seconds, with most under 1 second.
+
+## NGINX Plus
+
+### Test environment
+
+NGINX Plus: false
+
+GKE Cluster:
+
+- Node count: 3
+- k8s version: v1.27.8-gke.1067004
+- vCPUs per node: 2
+- RAM per node: 4022900Ki
+- Max pods per node: 110
+- Zone: us-central1-c
+- Instance Type: e2-medium
+
+NGF pod name -- ngf-longevity-nginx-gateway-fabric-fc7f6bcf-cnlww
+
+### Traffic
+
+HTTP:
+
+```text
+Running 5760m test @ http://cafe.example.com/coffee
+  2 threads and 100 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   173.03ms  120.83ms   2.00s    68.41%
+    Req/Sec   313.29    209.75     2.11k    65.95%
+  211857930 requests in 5760.00m, 74.04GB read
+  Socket errors: connect 0, read 307, write 0, timeout 118
+  Non-2xx or 3xx responses: 6
+Requests/sec:    613.01
+Transfer/sec:    224.63KB
+```
+
+HTTPS:
+
+```text
+Running 5760m test @ https://cafe.example.com/tea
+  2 threads and 100 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   173.25ms  120.87ms   2.00s    68.37%
+    Req/Sec   312.62    209.06     1.95k    66.02%
+  211427067 requests in 5760.00m, 72.76GB read
+  Socket errors: connect 0, read 284, write 0, timeout 92
+   vresponses: 4
+Requests/sec:    611.77
+Transfer/sec:    220.77KB
+```
+
+Note: Non-2xx or 3xx responses correspond to the error in NGINX log, see below.
+
+### Logs
+
+nginx-gateway:
+
+a lot of expected "usage reporting not enabled" errors.
+
+```text
+INFO 2024-03-20T14:13:00.372305088Z [resource.labels.containerName: nginx-gateway] {"level":"info", "msg":"Wait completed, proceeding to shutdown the manager", "ts":"2024-03-20T14:13:00Z"}
+ERROR 2024-03-20T14:13:00.374159128Z [resource.labels.containerName: nginx-gateway] {"error":"leader election lost", "level":"error", "msg":"error received after stop sequence was engaged", "stacktrace":"sigs.k8s.io/controller-runtime/pkg/manager.(*controllerManager).engageStopProcedure.func1 sigs.k8s.io/[email protected]/pkg/manager/internal.go:490", "ts":"2024-03-20T14:13:00Z"}
+```
+
+The error occurred during shutdown. Needs further investigation if the shutdown process should be fixed.
+https://github.com/nginxinc/nginx-gateway-fabric/issues/1735
+
+nginx:
+
+```text
+ERROR 2024-03-17T21:11:11.017601264Z [resource.labels.containerName: nginx] 2024/03/17 21:11:10 [error] 43#43: *211045372 no live upstreams while connecting to upstream, client: 10.128.0.19, server: cafe.example.com, request: "GET /tea HTTP/1.1", upstream: "http://longevity_tea_80/tea", host: "cafe.example.com"
+```
+
+10 errors like that occurred at different times. They occurred when backend pods were updated. Not clear why that happens.
+Because number of errors is small compared with total handled requests (211857930 + 211427067), no need to further
+investigate unless we see it in the future again at larger volume.
+
+### Key Metrics
+
+#### Containers memory
+
+![plus-memory.png](plus-memory.png)
+
+Drop in NGINX memory usage corresponds to the end of traffic generation.
+
+#### NGF Container Memory
+
+![plus-ngf-memory.png](plus-ngf-memory.png)
+
+### Containers CPU
+
+![plus-cpu.png](plus-cpu.png)
+
+Drop in NGINX CPU usage corresponds to the end of traffic generation.
+
+### NGINX Plus metrics
+
+![plus-status.png](plus-status.png)
+
+Drop in request corresponds to the end of traffic generation.
+
+### Reloads
+
+Rate of reloads - successful and errors:
+
+![plus-reloads.png](plus-reloads.png)
+
+Note: compared to NGINX, we don't have as many reloads here, because NGF uses NGINX Plus API to reconfigure NGINX
+for endpoints changes.
+
+However, small spikes, correspond to periodic reconciliation of Secrets, which (incorrectly)
+triggers a reload -- https://github.com/nginxinc/nginx-gateway-fabric/issues/1112
+
+No reloads finished with an error.
+
+Reload time distribution - counts:
+
+![plus-reload-time.png](plus-reload-time.png)
+
+Reload related metrics at the end:
+
+![plus-final-reloads.png](plus-final-reloads.png)
+
+All successful reloads took less than 1 seconds, with most under 0.5 second.
+
+## Comparison with previous runs
+
+If we compare with 1.1.0 results, we will see that NGF container memory usage is 2 times higher.
+That is probably due to a bug in metric visualization for 1.1.0 results (using mean instead of sum for aggregation).
+Running 1.1.0 in a similar cluster yields only slightly less memory usage (-2..-1MB)
+
+![oss-1.1.0-memory.png](oss-1.1.0-memory.png)