How to run ngrok in background?

Question

I tried running ngrok in the background with following command:

./ngrok -subdomain test -config=ngrok.cfg 80 &

the process is running:

[1] 3866

and the subdomain doesn't work.

It works with:

./ngrok -subdomain test -config=ngrok.cfg 80

Does anyone know what is going wrong here?

Thank you.

Erosive

Answer 1

as explained here

ngrok -log=stdout 80 > /dev/null &

Erosive

Does not work for ngrok2. Any ideas for the new version? – Underline

@toas939 Oh, thanks man! Too much answers, and none of them is correct. – Lightship

If you want to run this in a production environment and without having to open up your terminal, you can create and run ngrok as a service that will automatically start when your machine boots. Check here for instructions. ngrok.com/docs/ngrok-link#service – Africanize

@dave4jr: Is ngrok-link included in the ngrok client or does one have to install something else? The service command isn't recognized by ngrok – Decanter

@Decanter Unfortunately it does cost a little extra, I forget how much our company paid for this but I don't remember it being a lot. – Africanize

Okay. I asked because I already have a paid account but it still didn't work. Well, thanks anyway. – Decanter

I want to ngrok a folder into the background... how can I do this? ./ngrok http file:///my-folder -log=stdout http > /dev/null & doesn't work :( – Hasid

How can I get obtain its output? – Gonzalez

As of version 2.0.24, ngrok http 80 --log=stdout > ngrok.log & did the trick. – Heroics

Answer 2

as described previously you can run ngrok in background with

./ngrok http 8080 > /dev/null &

next you can use curl and for example jq a command-line JSON processor.

export WEBHOOK_URL="$(curl http://localhost:4040/api/tunnels | jq ".tunnels[0].public_url")"

your URL will be accessible from $WEBHOOK_URL env variable and you can use it anywhere.

Cantonese

This is by far the best solution for programatically accessing it! – Picked

did you check it? – Concertmaster

I might suggest curl --silent (or curl -s) and jq -r to have quieter output. So: $(curl -s http://localhost:4040/api/tunnels | jq -r '.tunnels[0].public_url') inside the double quotes. (Feel free to pull this into the answer; leaving it as a comment for now.) – Babylon

This is not deterministic if you have more than one tunnel. A simple workaround is to force just one tunnel by using only HTTPS: ngrok http --bind-tls=true --log=stdout 8080 > /dev/null & – Passionate

jq: error: Could not open file .tunnels[0].public_url: No such file or directory – Gonzalez

Answer 3

Easy: ngrok http 80 --log=stdout > ngrok.log & did the trick.

Geoid

nohup ngrok http 80 --log=stdout > ngrok.log & seems like safer in case ssh connection is dead – Gonzalez

In 2024, top 2 answers did not work. Only this one did. – Evelinevelina

Answer 4

Visit http://localhost:4040/status on your local machine, or see more here: View random ngrok URL when run in background.

Peking

Or sign up for a free account on the ngrok site and connect your local install to it - then you can view your active tunnels online. – Splore

Answer 5

Here's a little bash script I wrote which runs ngrok in the background. It then tries to sets a NGROK_PUBLIC_URL variable by calling a curl command (against http://127.0.0.1:4040/api/tunnels) followed by a sed command (which extracts the ngrok public URL). This all runs inside a loop until NGROK_PUBLIC_URL has a valid value as it normally takes ngrok 2 or 3 seconds for it's tunnels to become established.

start-ngrok.sh

#!/bin/sh

# Set local port from command line arg or default to 8080
LOCAL_PORT=${1-8080}

echo "Start ngrok in background on port [ $LOCAL_PORT ]"
nohup ngrok http ${LOCAL_PORT} &>/dev/null &

echo -n "Extracting ngrok public url ."
NGROK_PUBLIC_URL=""
while [ -z "$NGROK_PUBLIC_URL" ]; do
  # Run 'curl' against ngrok API and extract public (using 'sed' command)
  export NGROK_PUBLIC_URL=$(curl --silent --max-time 10 --connect-timeout 5 \
                            --show-error http://127.0.0.1:4040/api/tunnels | \
                            sed -nE 's/.*public_url":"https:..([^"]*).*/\1/p')
  sleep 1
  echo -n "."
done

echo
echo "NGROK_PUBLIC_URL => [ $NGROK_PUBLIC_URL ]"

The script takes a port as an optional command line argument i.e.

$ . start-ngrok.sh 1234

Run NGROK in background on port [ 1234 ]
Extracting ngrok public url ...
NGROK_PUBLIC_URL => [ 75d5faad.ngrok.io ]

... but will run on port 8080 if the port isn't supplied ...

$ . start-ngrok.sh 

Run NGROK in background on port [ 8080 ]
Extracting ngrok public url ...
NGROK_PUBLIC_URL => [ 07e7a373.ngrok.io ]

The NGROK_PUBLIC_URL now contains the public url i.e.

$ echo $NGROK_PUBLIC_URL
07e7a373.ngrok.io

This can be accessed / used in your applications.

Note: This script needs to be sourced (. start-ngrok.sh OR source start-ngrok.sh). This is because it is setting an environment variable which wont be available if run normally in a new shell (i.e. ./start-ngrok.sh). See https://superuser.com/q/176783 for more info.

You can also create a little script using pkill / kill etc to stop the background ngrok process: -

stop-ngrok.sh

#!/bin/sh

echo "Stopping background ngrok process"
kill -9 $(ps -ef | grep 'ngrok' | grep -v 'grep' | awk '{print $2}')
echo "ngrok stopped"

Diachronic

but this still does not run in the background. It kills when i close the terminal – Aestival

It doesn't on mine - that's what the nohup (no hangup) command does - nohup ngrok http ${LOCAL_PORT} &>/dev/null & - see en.wikipedia.org/wiki/Nohup for more details. – Diachronic

To kill the proces you could have issued a simple: kill -9 "$(pgrep ngrok)" – Novak

Very nice, never used pgrep before, thanks for sharing! – Diachronic

Answer 6

In Ngrok 2, -log is neither necessary nor available (though you can control log levels in the configuration file). ngrok > /dev/null & is sufficient.

Whitworth

But how do I know the URL to access my service? – Peking

If you want to do that, you'll have to run it in the foreground (AFAIK). Background running is primarily helpful for running as a service, when you'd more than likely know your domain. – Whitworth

See my answer, there is a way. – Peking

Also Artem's answer, https://mcmap.net/q/398652/-how-to-run-ngrok-in-background (with a comment from me to slightly modify it.) – Babylon

@Oliv: The easiest way of checking the URL is to log in into the Ngrok web page and using the Dashboard. – Tammitammie

Answer 7

If you want to use multiple shell windows or run any service in the background from a single SSH session that the simplest way is to use screen.

To install on the Centos Linux use yum install screen

Then start like any other command screen, after that type ngrok command within a parameters.

Detaching is the most powerful part of screen. Screen allows you to detach from a window and reattach later.

If your network connection fails, screen will automatically detach your session! You can detach from the window using “Ctrl-a” “D”.

This will drop you back into your shell.

All screen windows are still there and you can re-attach to them later using screen -r

Garbo

It is generally considered a bad answer if you can't use your answer without the link. – Tarazi

Answer 8

curl http://127.0.0.1:4040/api/tunnels 

and you will see the public_url infomation .

Here's example . https://i.sstatic.net/V0905.png

Jovi

Answer 9

Run ./ngrok http 5000 > /dev/null & then curl localhost:4040/status to check url

Formulaic

need correction , nohup ./ngrok http 5000 > /dev/null & so when we close terminal. process will not get kill – Estray

but this still does not run in the background – Aestival

@Aestival Sorry I didn't put it in my answer. But please check out the nohup suggestion as the above comment says. – Formulaic

Answer 10

Run ./ngrok http (port number) & This runs the ngrok tunnel as a background process. Ngrok usually opens a windown showing the assigned URL but since we are using the nohup command this is not visible.

Thus, then run curl http://127.0.0.1:4040/api/tunnels too see the URL assigned by ngrok

Florida

updated before, but no longer works. Failed to connect to localhost port 4040: Connection refused. see https://mcmap.net/q/398652/-how-to-run-ngrok-in-background answer – Semester

but this still does not run in the background. It kills when i close the terminal – Aestival

Answer 11

so i tried everything but the best answer to this which works in the year 2020 is:

how to create public local host(8080):

ngrok -log=stdout 80 > ngrok.log &

then

curl http://127.0.0.1:4040/api/tunnels

Aestival

Can confirm, best answer for 2020. – Inhalation

doesn't work with ngrok==2.3.35 Incorrect Usage: flag provided but not defined: -log – Individual

use ngrok --log=stdout 80 > ngrok.log & instead – Acidity

Answer 12

try to run as service. and check it from ngrok website. I tried for ngrok version 2.2.8 on a Raspberry pi 3.

ngrok.service as

[Unit]
Description=Share local port(s) with ngrok
After=syslog.target network.target

[Service]
Type=simple
Restart=always
RestartSec=1min
StandardOutput=null
StandardError=null
ExecStart=/usr/local/sbin/ngrok start --log /var/log/ngrok.log --config /etc/ngrok.yml --all
ExecStop=/usr/bin/killall ngrok

[Install]
WantedBy=multi-user.target

configuration file: ngrok.yml authtoken:

tunnels:
  <your Tunel Name >:
    proto: http
    addr: 80

Adduce

Answer 13

Use below script for ngrok2

nohup ngrok http 3000 &

This will write logs to file nohup.out

Pharr

nohup.out will not then contain sufficient information to know the API tunnel in use. See Hemanth's response. – Waxler

Answer 14

nohup ./ngrok http 80 &

Hit localhost:4040 to get the public URL assigned by ngrok

Filament

Answer 15

You can use screen for that. Here is an example of how I use it:

screen -d -m ~/./ngrok http test.cc:8080

Mediation

Answer 16

Ngrok now has its own solution for it, which is "installing as a service."

This will start the service on machine boot and restart the service automatically in case of any failure. There is an official document that explains it precisely: https://ngrok.com/docs/secure-tunnels/ngrok-agent/installing-as-a-service/

Bellanca

Answer 17

nohup /usr/local/bin/ngrok --config /etc/ngrok.yml http 8080 &

If you link with ngrok account, then you can view the public url in ngrok site, do not need to curl the local url Public url https://dashboard.ngrok.com/status

Sepoy

Answer 18

You can use cotunnel. It is ngrok alternative. The cotunnel installation script creates service and works itself on the background.

Collage

I think is kinda too much to say it's an alternative... It tries to be but it's way too far away from ngrok as in the flexibility. Plus, honestly, I don't like the ideea that someone is able to ssh into my server without any user/pass directly from their site. From a security perspective, this sucks big time! Installed, checked, uninstalled. Period! – Novak

Answer 19

Another alternative is using the ngrok npm module. If you have Node installed, you can run ngrok and print out the URL as shown below:

require('ngrok').connect({ proto: 'http', port: 3000 }).then(url => {
  console.log(url);
});

Not strictly running it in the background, but I find this to be the easiest approach for my requirements: starting ngrok and a web server that's aware of its ngrok url in a single command.

Salify

Answer 20

./ngrok http 80 -log=stdout > /dev/null &

Ching

Please add some explanation to your answer such that others can learn from it - to me, this looks like a duplicate of the existing answers – Chamade

Answer 21

In Windows Batch Script (.bat), if you want to execute next command without waiting ngrok, use the following command with start /b:

start /b ngrok http 80 --log=stdout > ngrok.log &

Brandenbrandenburg

Answer 22

Two steps:

1. First set console_ui to false in your config file (.ngrok2/ngrok.yml)

2. Run command like this

   $ ./ngrok start demo &
   

Extra: if you started this via ssh and you want it to continue running even if you disconnect run it like this

nohup ./ngrok start demo &

Example of my config file

    authtoken: XXXXX
    region: us
    console_ui: false
    web_addr: localhost:4040


    tunnels:    
      demo:
        proto: http
        addr: 9090
        hostname: demo.mysite.com
        inspect: false
        auth: "demo:secret"

Nonrecognition