Go `docker system df` 与 `systemdf` (docker api 端点)

我正在编写一个Go程序，以便从我的扩展底座主机获取以GB为单位的总磁盘使用量.为此，我使用来自Go lib的Func DiskUsage():

• https://pkg.go.dev/github.com/docker/docker/client#Client.DiskUsage.

查看代码，此函数将调用docker API端点/system/df:

• https://docs.docker.com/engine/api/v1.43/#tag/System/operation/SystemDataUsage个

然而，当我使用这个库与使用命令docker system df计算GB时，我注意到一个奇怪的行为:

• docker system df输出:

  $ docker system df
  TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
  Images          223       4         21.02GB   20.7GB (98%)
  Containers      6         0         0B        0B
  Local Volumes   13        1         536.4MB   340.4MB (63%)
  Build Cache     954       0         13.51GB   13.51GB
  

• 我的GO应用程序输出:

  $ go run ./cmd/main.go
  Images: TOTAL (223), 17GB
  Build Cache: TOTAL (954), 29GB
  

正如您所看到的，我们在两个输出之间存在差异.I would like a help to understand if I am doing something wrong with this calculation which gets data from the 100 endpoint.谢谢:)

GO申请:

package main

import (
    "context"
    "fmt"

    "github.com/docker/docker/api/types"
    "github.com/docker/docker/client"
)

func main() {
    cli, err := client.NewClientWithOpts(client.FromEnv)
    if err != nil {
        panic(err)
    }

    diskUsg, err := cli.DiskUsage(context.Background(), types.DiskUsageOptions{})
    if err != nil {
        panic(err)
    }
    b := float64(0)
    for _, ch := range diskUsg.BuildCache {
        b = b + float64(ch.Size)
    }

    b2 := float64(0)
    for _, ch := range diskUsg.Images {
        if ch.Size > ch.SharedSize {
            b2 = b2 + (float64(ch.Size) - float64(ch.SharedSize))
            continue
        }
        b2 = b2 + (float64(ch.SharedSize) - float64(ch.Size))
    }

    fmt.Printf("Images: TOTAL (%d), %2.fGB\n", len(diskUsg.Images), float64(b2)/(1<<30))
    fmt.Printf("Build Cache: TOTAL (%d), %2.fGB\n", len(diskUsg.BuildCache), float64(b)/(1<<30))
}