image: alping docker what does it mean code example

Example 1: image: alping docker what does it mean

time docker run --rm alpine sh -c "apk update && apk add curl"

real	0m3.040s
user	0m0.017s
sys	0m0.008s

Example 2: image: alping docker what does it mean

time docker run --rm debian sh -c "apt-get update && apt-get install curl"

real	0m9.170s
user	0m0.000s
sys	0m0.031s