How to script the startup of an app using multiple precursory values?

Question

I have a webapp I'd like to start with a script, rather than open 3 tabs and start the processes, then change a line to a config file, and then start the web server. First, so I can test webhooks, I need to run ngrok http https://localhost:3000, which yields something just as so-- ngrok by @inconshreveable (Ctrl+C to quit) Session Status online Account myemail@gmail.com (Plan: Free) Version 2.3.35 Region United States (us) Web Interface http://127.0.0.1:4040 Forwarding http://2f22e8990cbe.ngrok.io -> https://localhost:3000 Forwarding https://2f22e8990cbe.ngrok.io -> https://localhost:3000 Connections ttl opn rt1 rt5 p50 p90 13973 1 0.00 0.07 0.00 0.00 I then change a config file to accommodate the new host (random for the free usage of ngrok) # development.rb config.hosts << '2f22e8990cbe.ngrok.io' # (tunnel address from above) I then save the file and start the webserver. $ rails server puma --bind 'ssl://127.0.0.1:3000?key=/home/oaty/.ssh/localhost.key&cert=/home/oaty/.ssh/localhost.crt' I'd like to script this into one command. I can use a larger, shell environment variable for the ngrok host, tho I have to get that somehow from the same script, to begin with. I hope I'm not asking too much. I really love the Ubuntu forums. I'm too Autistic, I guess, for most other places. Viva Ubuntu!

tidelake · Answer

I found a solution by drilling down more accurately. I've adapted the code a little. The curl with jq command is the real pearl. Thank you.
(Note: localhost:4040 is ngrok's web ui page.)
boot_ssl.sh
#!/bin/bash
sh -c 'ngrok http https://localhost:3000 &'
sleep 2
curl --silent http://127.0.0.1:4040/api/tunnels | jq '.tunnels[0].public_url' > .ngrok_ssl_host
rails s puma -b 'ssl://127.0.0.1:3000?key=/home/jess/.ssh/localhost.key&cert=/home/jess/.ssh/localhost.crt'

and then in the config/development.rb file... :)
  NGROK_SSL_HOST = File.open('.ngrok_ssl_host').read.match(/[0-9a-z]{12}.ngrok.io/)[0]
  
  config.hosts << NGROK_SSL_HOST

waltinator · Answer

Something like:
newhost=$(ngrok http https://localhost:3000 | 
    grep -E '^Forwardings+https://' | 
    grep -E  -o '[0-9a-f]{12}.ngrok.io`)
  
if [[ -n "$newhost" ]] ; then
    echo "$newhost" >>config.hosts
    rails server ...(the rest)
else
    echo "Failure in ngrok" >&2
fi

Read man grep bash.

How to script the startup of an app using multiple precursory values?

2 Answers

boot_ssl.sh

and then in the config/development.rb file... :)

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