How to convert a kubernetes style time elapsed into seconds so I can do some comparisons

Question

From

kubectl get pods -o wide

The output looks similar to

some-pod-name-with-numbers-123             1/1     Running   0          6d4h      192.168.0.23   node-name-abcdeft-host.domain   <none>           <none>
some-pod-name-with-numbers-1234            1/1     Running   0          4h38m      192.168.0.24   node-name-abcdeft-host.domain   <none>           <none>
some-pod-name-with-numbers-1235            1/1     Running   0          2m38s      192.168.0.25   node-name-abcdeft-host.domain   <none>           <none>

I get time elapsed for the pods in a format like: 4d3h15m3s (it looks like the most is two consecutive units, days and hours, hours minutes, minutes and seconds, but I can't guarantee that.

I need to check to see if a pod has been around longer than some threshold X.

I tried to find some way of extracting this field as seconds via kubectl, no luck there. I searched the internet for a pre-canned solution, could not find one.

I'm thinking that I can use awk to convert the string into a numeric seconds so I can then compare if it is > $X, this value is configurable.

Answer 1

You don't need to fork an external process just to get the kubernetes elapsed time in seconds. The below GNU awk code has a user defined function fx() which shall do that conversion and from there on you can use it for your comparison purposes.

kubectl get pods -o wide |
awk '
BEGIN {
    a["d"] = 24*(\
    a["h"] = 60*(\
    a["m"] = 60*(\
    a["s"] = 1)));
  }
  {
    print fx($5); # kubernetes time elapsed in seconds 
  }
  function fx(ktym,    f,u,n,t,i) {
    n = split(ktym, f, /[dhms]/, u)
    t = 0
    for (i=1; i<n; i++) {
      t += f[i] * a[u[i]] 
    }
    return t
  }
'

In case you want to go by a user defined function in bash then we can do the following. We have a function fx() which needs one arg, which is the time elapsed in kubernetes format abd it will output a time in seconds.

fx() {
echo "$1" |
sed -Ee '
  s/[1-9][0-9]*[dhms]/&+ /g
  :a;s/[+]([^+].*)/\1+/;ta
  s/.$//
  :loop
    s/d/ 24h*/
    s/h/ 60m*/
    s/m/ 60s*/
    s/s//
  t loop
  s/.*/echo "&" | dc -e "?p"/e
'
}

We are dynamically generating a code for the Linux utility called dc or the desk calculator in the RPN (Reverse Polish Notation).

Answer 2

In case anyone was looking for a python fucntion like myself, here it is:

def kubctle_dur_to_secs(kubectl_time:str) -> int:
    total_time = 0
    for t_char, sec_in_t in zip( ('d', 'h', 'm', 's'), (86400, 3600, 60, 1) ):
        if t_char in kubectl_time:
            t_index = kubectl_time.find(t_char)
            total_time += int(kubectl_time[:t_index])*sec_in_t
            kubectl_time = kubectl_time[t_index+1:]
    return total_time

Answer 3

Spent some time on this, figured out the quickest way to get this was to tokenize the time with a sed replace.

sed -e 's/\([smhd]\)/\1 /g' | awk '{ b=0; for(i=1; i<=NF; ++i) { s=substr($i,1,length($i)-1); u=substr($i,length($i)); if (u=="s") b+=s; else if (u=="m") b+=s*60; else if (u=="h") b+=s*60*60; else if (u=="d") b+=s*60*60*24; else u=""; } if (b>1) printf "%d", b}'

So far I've only observed d,h,m,s units being used in this field, even for pods that are >100days old.

The sed command basically split every unit with a space.
Awk then loop through the fields and split the string into the unit (u) and the numeric string (s).
The chained if-elseif-else statements simply converts the values into seconds based on the unit and adds it to a running total of the time in seconds is kept.

I've placed this command in a script "kube_elapsed_to_seconds" and planning to use another awk on the outside and the system command to run this script on this field.

kubectl get pods -o wide | awk '{ system("echo " $5 " | kube_elapased_to_seconds"); print $0 }'

I'm open to suggestions on how to make this command easier to read or interact better with other non-time related fields like podname and status that might be present.

Answer 4

convert the string into a numeric seconds so I can then compare if it is > 3600

3600 seconds is an hour, so you just need to check if we have at least one hour mentioned in the output:

echo 4d3h15m3s | grep -q '[dh]' && echo At least 3600 seconds

To match against the fifth field in the actual output use awk, but this requires that none of the preceding field values contains a space

kubectl get pods -o wide | awk '{ exit ($5 ~ /[dh]/) ? 0 : 1 }' && echo At least 3600 seconds

If you need non-boundary comparisons, you will need to convert the timespec into a number of seconds. Here's a perl version

perl -e '
    %t=(d => 3600*24, h => 3600, m => 60, s => 1);    # Seconds per unit
    @a=split(/([dhms])/, shift);                      # Tokenise string argument
    for ($i = 0; $i < scalar @a; $i += 2) {
        $s += $a[$i] * $t{$a[$i+1]}                   # Add N lots of seconds-per-unit
    };
    print "$s\n"
' 4d3h15m3s

Answer 5

For a command that understands those 4d3h15m3s, see dateutils's dadd:

$ TZ=UTC0 dateutils.dadd -f%s 1970-01-01T00:00:00 4d3h15m3s
357303

Here adding that duration to the start of Unix epoch time, and outputting the result as Unix epoch time, in a timezone with 0 offset to UTC.