I am trying to develop a command line tool using cobra. I would like to provide flags like kubectl offers to its users. As a first step I would like to implement kubectl standard format like this:
kubectl get pods -n mpo
NAME READY STATUS RESTARTS AGE
my-deployment-5588bf7844-n2nw7 1/1 Running 0 3d
my-deployment-5588bf7844-qcpsl 1/1 Running 0 3d
How do I implement an output format like this?
You can format strings in Go with padding on either side. See this post for example.
Below, I format all strings with right padding. The first column gets 40 char padding as the pod name might be long. The other columns get only 10 chars padding.
fmt.Printf("%-40s %-10s %-10s\n", "NAME", "READY", "STATUS")
fmt.Printf("%-40s %-10s %-10s\n", "my-deployment-5588bf7844-n2nw7", " 1/1", "Running")
fmt.Printf("%-40s %-10s %-10s\n", "my-deployment-5588bf7844-n2nw7", " 1/1", "Running")
}
https://play.golang.com/p/8ZZH5XmqTpR
That said, using tabwriter, may be another, potentially even better option.
// io.Writer, minwidth, tabwidth, padding int, padchar byte, flags uint
w := tabwriter.NewWriter(os.Stdout, 10, 1, 5, ' ', 0)
fmt.Fprintln(w, "NAME\tREADY\tSTATUS")
fmt.Fprintln(w, "my-deployment-5588bf7844-n2nw7\t1/1\tRunning")
fmt.Fprintln(w, "my-deployment-5588bf7844-n2nw7\t1/1\tRunning")
w.Flush()