How to extract kubernetes pod command execution result attributes - go

Question

I am connecting to pod via client-Go and I want to get the properties of the file directory
func GetPodFiles(c *gin.Context) {
client, _ := Init.ClusterID(c)
path := c.DefaultQuery("path", "/")
cmd := []string{
"sh",
"-c",
fmt.Sprintf("ls -l %s", path),
}
config, _ := Init.ClusterCfg(c)
req := client.CoreV1().RESTClient().Post().
Resource("pods").
Name("nacos-0").
Namespace("default").SubResource("exec").Param("container", "nacos")
req.VersionedParams(
&v1.PodExecOptions{
Command: cmd,
Stdin: false,
Stdout: true,
Stderr: true,
TTY: false,
},
scheme.ParameterCodec,
)
var stdout, stderr bytes.Buffer
exec, err := remotecommand.NewSPDYExecutor(config, "POST", req.URL())
if err != nil {
response.FailWithMessage(response.InternalServerError, err.Error(), c)
return
}
err = exec.Stream(remotecommand.StreamOptions{
Stdin: nil,
Stdout: &stdout,
Stderr: &stderr,
})
if err != nil {
response.FailWithMessage(response.InternalServerError, "Error obtaining file", c)
return
}
fmt.Println(stdout.String())
}
Execution Result Output
total 0
lrwxrwxrwx 1 root root 7 Jun 1 2018 bin -> usr/bin
drwxr-xr-x 5 root root 360 Feb 16 16:39 dev
lrwxrwxrwx 1 root root 8 Jun 1 2018 sbin -> usr/sbin
drwxr-xr-x 2 root root 6 Apr 11 2018 srv
Expect the result
"data": [
{
"perm": "drwxr-xr-x",
"mod_time": "2022-03-02 15:02:15",
"kind": "d",
"name": "temp",
"size": ""
},
]
Is there a good way or a golang third-party library to handle it. Please let me know. Thank you

Answer 1

In a Kubernetes pod you can execute the stat linux command instead of ls command.
$ stat yourFileOrDirName
The output of this command by default is like this:
File: yourFileOrDirName
Size: 346 Blocks: 0 IO Block: 4096 directory
Device: 51h/82d Inode: 40431 Links: 1
Access: (0755/drwxr-xr-x) Uid: ( 1000/ username) Gid: ( 1000/ groupname)
Access: 2022-03-02 11:59:07.384821351 +0100
Modify: 2022-03-02 11:58:48.733821177 +0100
Change: 2022-03-02 11:58:48.733821177 +0100
Birth: 2021-12-21 11:12:05.571841723 +0100
But you can tweak its output like this:
$ stat --printf="%n,%A,%y,%s" yourFileOrDirName
where %n - file name, %A - permission bits and file type in human readable form, %y - time of last data modification human-readable, %s - total size, in bytes. You can also choose any character as a delimiter instead of comma.
the output will be:
yourFileOrDirName,drwxr-xr-x,2022-03-02 11:58:48.733821177 +0100,346
See more info about the stat command here.
After you get such output, I believe you can easily 'convert' it to json format if you really need it.
Furthermore, you can run the stat command like this:
$ stat --printf="{\"data\":[{\"name\":\"%n\",\"perm\":\"%A\",\"mod_time\":\"%y\",\"size\":\"%s\"}]}" yourFileOrDirName
Or as #mdaniel suggested, since the command does not contain any shell variables, nor a ', the cleaner command is:
stat --printf='{"data":[{"name":"%n","perm":"%A","mod_time":"%y","size":"%s"}]}' yourFileOrDirName
and get the DIY json output:
{"data":[{"name":"yourFileOrDirName","perm":"drwxrwxr-x","mod_time":"2022-02-04 15:17:27.000000000 +0000","size":"4096"}]}