How to run any program as Daemon

---

For code related details please refer below link

Reference: Go Daemon

Instructions on How to run any program as Daemon

---

1. Connect to your Ubuntu EC2 instance2.

2. Install Go Lang if not installed

   sudo add-apt-repository ppa:longsleep/golang-backports
   sudo apt-get update
   sudo apt-get install golang-go
   

   Also make sure that go version is 1.13 or above using command go version

3. Create 2 New Folders - One each for logs and config file, and note down the folder location as we will need it again while writing the code. For my code I have created folders with respective addresses using following commands

   mkdir /home/ubuntu/logs
   mkdir /home/ubuntu/configs
   

4. Open your configs folder and create following config file. Here I am creating config file with name config.yml

   cd /home/ubuntu/configs
   cat > config.yml <<EOF
   service:
       name: testservicename
       port: 8000
       timer: 60
   logfile:
       location: /home/ubuntu/logs
       name: testservice.log
   EOF
   

   Please make sure to make all necessary changes in config.yml based on your requirements and changes you need

5. Now go to any folder you want to create your Go Lang Code, here in my case I am creating the sample program inside /home/ubuntu/sample. (Command used to create the directory mkdir /home/ubuntu/sample)

6. Create main.go file in your local editor before you move it to EC2. Take a copy of this code Code and now edit it according to your requirements.

   • First place that you will have to edit is constants defined in the code. Make sure the config file location is correct

     const (
         description = "some description of the program"
         // This needs to be configured properly with a static file address (don't use relative address here)
         configFile = "/home/ubuntu/configs/config.yml"
     )
     

   • Second place that you will have to change is logic inside function yourMethod(). Update the function name as per your requirement. Function yourMethod() contains the logic that you want to be executed in specified interval of time on repeating loop. Another way around is to directly call your intended function that you want to run, just simply by exporting it as public method. Then you can call it from the ticker section of Manage() function.

7. After you have finalised all changes to the code, copy the code to your ec2 instance. You can use vi editor to paste the code

   vi main.go
   #This will open an editor, now go to Insert mode by clicking 'i' then paste the code in main.go
   #Now save the file by pressing escape and then entering :wq! then press enter
   

   if you are using/referring your custom public method then make sure to copy the whole package to EC2

8. Now build the code using command go build. Now in case of following errors:
   • Package missing error use go get package-name
   • Config File/Log File related error, make sure to create/use correct location address in your code
   • In case of any other issues/error resolve them based on error message

9. If the build is successful you will get an executable file to run. In our code we have defined 5 types of arguments - install, start, status, stop and remove

   • install - Registers your program as a daemon service
   • start - Starts your program
   • status - Shows status of your process
   • stop - Stops the running process
   • remove - Removes/Uninstalls the registered service

   First thing you need to do is install the service using command

   ./testservicename install
   

   Then start the service using command

   ./testservicename start
   

   Now check the status for your service

   ./testservicename status
   

   Status should be shown as running, but if it is stopped then check logs for any issues and check your code properly. For me most frequent reason for this was using unavailable port number

   To stop your service use

   ./testservicename stop
   

   and to Uninstall your service use

   ./testservicename remove
   

10. Our service will log all our data to our specified logfile location. Go to logfile location and check the log file using command cat testservice.log or tail -n num testservice.log where num is the number of bottom last lines you want to be displayed.

Important Note

Value for timer in config file is by default defined in ns i.e Nano Seconds but in our code we have statically modified it to seconds. So…

timer: 60 means 1 minute

timer: 600 means 10 minutes

timer: 3600 means 1 hour