Add high CPU demo

Author: monodot

monitoring/cpu/README.md

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+# container-monitoring-demo
+
+This is a demo of how to monitor containers with simple Docker commands.
+
+## To run
+
+**Pre-requisites:** You need to have Docker installed and running first. See [Docker's installation instructions](https://docs.docker.com/engine/installation/) for more information.
+
+Once you've cloned this repo, run this to build the demo app:
+
+```bash
+docker build -t highcpu-go highcpu-go
+
+docker run --rm --name highcpu-go -d highcpu-go
+```
+
+### Monitoring with docker stats
+
+The app is designed to oscillate between using 100% CPU and 0% CPU.
+
+You can see the container's CPU usage with `docker stats`. We'll run the command with a screen refresh interval of 1 second:
+
+```bash
+docker stats --interval 1
+```
+
+You should see something like this:
+
+```bash
+ID            NAME         CPU %       MEM USAGE / LIMIT  MEM %       NET IO       BLOCK IO    PIDS        CPU TIME      AVG CPU %
+2b56db050efb  highcpu-go   99.97%      528.4kB / 16.47GB  0.00%       430B / 110B  0B / 0B     4           2m20.636994s  50.09%
+```
+
+You should see the CPU column increase and decrease over time.
+
+### Monitoring with docker top
+
+You can also monitor the individual process inside the container with `docker top`:
+
+```bash
+docker top highcpu-go
+```
+
+You should see something like this:
+
+```bash
+USER        PID         PPID        %CPU        ELAPSED         TTY         TIME        COMMAND
+root        1           0           50.130      6m26.99324902s  ?           3m14s       ./highcpu-go
+```
+
+You should see the CPU column increase and decrease over time.
+
+### Monitoring with docker logs
+
+You can also monitor the container's logs with `docker logs`:
+
+```bash
+docker logs -f highcpu-go
+```
+

monitoring/cpu/highcpu-go/Dockerfile

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+FROM docker.io/library/golang:1.19
+
+COPY highcpu.go .
+
+RUN go build -o highcpu highcpu.go
+
+CMD ["./highcpu"]

monitoring/cpu/highcpu-go/highcpu.go

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+package main
+
+import (
+	"log"
+	"math"
+	"time"
+)
+
+func main() {
+	log.Println("Starting program")
+
+	for {
+
+		// Use 100% CPU for 5 seconds
+		startTime := time.Now()
+		log.Println("Starting CPU-intensive work")
+		for time.Since(startTime) < 5*time.Second {
+			// Perform a computationally expensive call:
+			// the square root of a big number!
+			math.Sqrt(999999999)
+		}
+
+		// Use less CPU for 5 seconds
+		startTime = time.Now()
+		log.Println("Starting CPU-light work")
+		for time.Since(startTime) < 5*time.Second {
+			time.Sleep(1 * time.Second)
+		}
+	}
+}

monitoring/cpu/highcpu-python/Dockerfile

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+FROM docker.io/library/python:3.6-alpine
+
+COPY . .
+
+CMD ["python", "app.py"]

monitoring/cpu/highcpu-python/app.py

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+import time
+
+while True:
+    # Use 100% CPU for 5 seconds
+    start_time = time.time()
+    while time.time() - start_time < 5:
+        pass
+
+    # Use 50% CPU for 5 seconds
+    start_time = time.time()
+    while time.time() - start_time < 5:
+        time.sleep(0.5)