scout/usage: add --docker flag to scout usage tool (#985)

prints CPU and Memory usage for each running container in a docker deployment of sourcegraph

Author: jasonhawkharris

internal/scout/usage/docker.go

@@ -2,27 +2,86 @@ package usage
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 
+	"github.com/charmbracelet/bubbles/table"
+	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/client"
+	"github.com/sourcegraph/sourcegraph/lib/errors"
+	"github.com/sourcegraph/src-cli/internal/scout/style"
 )
 
 func Docker(ctx context.Context, client client.Client, opts ...Option) error {
 	cfg := &Config{
-		namespace:     "default",
-		docker:        true,
-		pod:           "",
-		container:     "",
-		spy:           false,
-		k8sClient:     nil,
-		dockerClient:  &client,
-		metricsClient: nil,
+		namespace:    "default",
+		docker:       true,
+		pod:          "",
+		container:    "",
+		spy:          false,
+		dockerClient: &client,
 	}
 
 	for _, opt := range opts {
 		opt(cfg)
 	}
 
-	fmt.Println("Command is routed, but not yet fixed.")
+	containers, err := cfg.dockerClient.ContainerList(ctx, types.ContainerListOptions{})
+	if err != nil {
+		return errors.Wrap(err, "could not get list of containers")
+	}
+
+	return renderDockerUsageTable(ctx, cfg, containers)
+}
+
+// renderDockerUsageTable renders a table displaying CPU and memory usage for Docker containers.
+func renderDockerUsageTable(ctx context.Context, cfg *Config, containers []types.Container) error {
+	columns := []table.Column{
+		{Title: "Container", Width: 20},
+		{Title: "Cores", Width: 10},
+		{Title: "Usage", Width: 10},
+		{Title: "Memory", Width: 10},
+		{Title: "Usage", Width: 10},
+	}
+	rows := []table.Row{}
+
+	for _, container := range containers {
+		containerInfo, err := cfg.dockerClient.ContainerInspect(ctx, container.ID)
+		if err != nil {
+			return errors.Wrap(err, "failed to get container info")
+		}
+
+		stats, err := cfg.dockerClient.ContainerStats(ctx, container.ID, false)
+		if err != nil {
+			return errors.Wrap(err, "could not get container stats")
+		}
+		defer stats.Body.Close()
+
+		var usage types.StatsJSON
+		if err := json.NewDecoder(stats.Body).Decode(&usage); err != nil {
+			return errors.Wrap(err, "could not decode container stats")
+		}
+
+		row := makeDockerUsageRow(usage, containerInfo)
+		rows = append(rows, row)
+	}
+
+	style.ResourceTable(columns, rows)
 	return nil
 }
+
+// makeDockerUsageRow generates a table row displaying CPU and memory usage for a Docker container.
+func makeDockerUsageRow(containerUsage types.StatsJSON, containerInfo types.ContainerJSON) table.Row {
+	cpuCores := float64(containerInfo.HostConfig.NanoCPUs)
+	memory := float64(containerInfo.HostConfig.Memory)
+	cpuUsage := float64(containerUsage.CPUStats.CPUUsage.TotalUsage)
+	memoryUsage := float64(containerUsage.MemoryStats.Usage)
+
+	return table.Row{
+		containerInfo.Name,
+		fmt.Sprintf("%.2f", cpuCores/1_000_000_000),
+		fmt.Sprintf("%.2f%%", getPercentage(cpuUsage, cpuCores)),
+		fmt.Sprintf("%.2fG", memory/1_000_000_000),
+		fmt.Sprintf("%.2f%%", getPercentage(memoryUsage, memory)),
+	}
+}