How to monitor your aspnet core application on Ubuntu Linux

by Joche Ojeda | Sep 14, 2020 | Linux, netcore, Ubuntu

Here are some recommendations to host your new shiny aspnet core app on Linux in this case in Ubuntu 18.04

First, create a user with the name aspnetapp

sudo adduser myaspnetapp

after executing the command, you will have a new folder in your home directory the folder will have the same name as your username so in this case “myaspnetapp”

now let’s SSH to with the new user you just created you can do that using your favorite SSH client, for example, if you are using windows you can use putty

when you log in with the new user you will be in its home folder, now we can create a folder called app with the following command

mkdir app

your folder structure should look like this now

/home/myaspnetapp/app

Now we are ready to upload the files. By now should have already compiled and publish your application to run in Linux, if you have not done that yet then you should take a look to this article https://www.jocheojeda.com/2019/06/10/how-to-create-a-self-contained-netcore-3-console-application/

There are many options to upload a zip file but I think is the best way is to use the secure copy command from linux “scp”, I won’t explain how you should call the scp command but if you are using windows you can run that command from the WSL console and if you are using Linux the command is already built-in, anyway here is an article about it https://linuxize.com/post/how-to-use-scp-command-to-securely-transfer-files/

Here I will write an example of how the scp command should look like and you adjust it to your needs

scp publish.zip myaspnetapp@200.35.15.25:/home/myaspnetapp/app

so that command above will do the following, it will copy the file publish.zip from the local folder to a server running on the following the IP 200.35.15.25 and the folder “/home/myaspnetapp/app”

now let’s unzip the content of the folder zip with the following command

unzip publish.zip

What we have done so far:

1. We have created a user in the OS
2. We have created a folder to host our application within the user home folder
3. We have uploaded a zip file containing our application the folder “/home/myaspnetapp/app”

Now that the app is already in the server we need to change the permission of the folder where the app lives to 0777, you can learn more about Linux file system permissions here https://www.guru99.com/file-permissions.html

Creating a service to monitor the app

The next step to monitor our app is to use systemd is an init system that provides many powerful features for starting, stopping, and managing processes.

Let’s start by creating a service file in the following path “/etc/systemd/system/”

You can do that with the following command:

sudo nano /etc/systemd/system/MyExecutableFile.service

here is how the content of the file should look like

[Unit]

Description=A description of your app


[Service]

WorkingDirectory=/home/myaspnetapp /app

ExecStart= /home/ myaspnetapp /app/MyExecutableFile

Restart=always

# Restart service after 10 seconds if the dotnet service crashes:

RestartSec=10

KillSignal=SIGINT

SyslogIdentifier= MyExecutableFile

User=apache

Environment=ASPNETCORE_ENVIRONMENT=Production


[Install]

WantedBy=multi-user.target

Here is a little explanation of what you might need to change if the file above

WorkingDirectory: this is the working directory, usually is the same where the app lives

ExecStart: This is the executable file how what will you write here will depend on your application if its self-contained you just need to write the name the full path of the executable file otherwise you need to write the path to the dotnet runtime and then the path to your dll as show below:

/usr/local/bin/dotnet /var/www/helloapp/helloapp.dll

RestartSec: this is the time to wait before trying to restart the app after if the process crashes

SyslogIdentifier: the app identifier for sys logs

User: this is really important since the app will run under this user privileges, so you need to make sure that the user exists and that is able to access the files needed to start the app

That is all that we need for the service file now we need to go back to the console and enable our new service, you can do that with the following command

sudo systemctl enable MyExecutableFile.service

To start and stop the service you can use the following commands

//To Start
sudo systemctl start MyExecutableFile.service

//To Stop
sudo systemctl status MyExecutableFile.service