How can I execute next script that wait for the previous script to complete first? - bash

Question

In https://squidfunk.github.io/mkdocs-material/creating-your-site/#previewing-as-you-write, there's a command that will launch my document site.
docker run --rm -it -p 8000:8000 -v ${PWD}:/docs squidfunk/mkdocs-material
I want that after it is launch, I will automatically open the browser and see it.
I write a script as below
docker run --rm -it -p 8000:8000 -v ${PWD}:/docs squidfunk/mkdocs-material
open http://localhost:8000
But it turns out the open command cannot be triggered, as the previous docker run is still holding the process still.
If I use & as below, then the open will get called too fast before the page is ready
docker run --rm -it -p 8000:8000 -v ${PWD}:/docs squidfunk/mkdocs-material &
open http://localhost:8000
How can I get open called at the right time?
(FYI, I'm using GNU bash, version 3.2.57(1)-release)

Answer 1

How can I get open called at the right time?
Opening the browser at exactly the right time would require your server mkdocs to give some signal that it is ready. Since you probably don't want to modify the code of the server, you just have to wait for the right time and then open the page.
Either measure the startup time once by hand and then use a fixed wait time or check the page repeatedly until it loads.
In both cases, the docker command and the process of opening the page must run in parallel. bash can run run things in parallel using background jobs (... &). Since docker -it must run in the foreground, we run open as a the background job. This might seem a little strange, since we seemingly open the website before starting the server, but keep in mind that both commands run in parallel.
Either
# replace 2 with your measured time
sleep 2 && open http://localhost:8000 &
docker run --rm -it -p 8000:8000 -v "${PWD}:/docs" squidfunk/mkdocs-material
or
while ! curl http://localhost:8000 -s -f -o /dev/null; do
sleep 0.2
done && open http://localhost:8000 &
docker run --rm -it -p 8000:8000 -v "${PWD}:/docs" squidfunk/mkdocs-material

Answer 2

It sounds (to me) like:
docker run is a blocking process (it does not exit and/or return control to the console) so ...
the open is never run (unless the docker run command is aborted in which case the open will fail), and ...
pushing docker run into the background means the open is run before the URL is fully functional
If this is the case I'm wondering if you could do something like:
docker run ... & # put in background, return control to console
sleep 3 # sleep 3 seconds
open ...
NOTE: manually picking the number of seconds to sleep (3 in this case) isn't ideal but a decent number that guarantees URL availability and doesn't leave you hanging should be doable with some testing
Another 'basic' option might be a looping construct combined with a sleep, eg:
docker run ... &
while true # loop indefinitely
do
sleep 1 # sleep 1 sec
open ... 2>/dev/null # try the open
[[ $? == 0 ]] && break # if it doesn't fail then break out of loop, ie,
# if it does fail then repeat loop
done