Why docker container exits immediately

Question

I run a container in the background using

 docker run -d --name hadoop h_Service

it exits quickly. But if I run in the foreground, it works

Answer 1

Coming from duplicates, I don't see any answer here which addresses the very common antipattern of running your main workload as a background job, and then wondering why Docker exits.

In simple terms, if you have

my-main-thing &

then either take out the & to run the job in the foreground, or add

wait

at the end of the script to make it wait for all background jobs.

It will then still exit if the main workload exits, so maybe run this in a while true loop to force it to restart forever:

while true; do
    my-main-thing &
    other things which need to happen while the main workload runs in the background
    maybe if you have such things
    wait
done

(Notice also how to write while true. It's common to see silly things like while [ true ] or while [ 1 ] which coincidentally happen to work, but don't mean what the author probably imagined they ought to mean.)