Nodemon.io VS supervisor

nodemon

nodemon - automatically restarts our Node.js server whenever we make changes to the codebase

The nodemon is a popular library for running and restarting Node.js processes on file changes. All LTS Node.js support an option --watch-path, which allows to replace nodemon:

Or you can install nodemon for the same purpose. nodemon detects changes in the directory and restarts your application.

When I first encountered Node.js and also learned how to use Linux, nodemon was a library that I often used to develop applications, as it would automatically "reload" the new code upon saving without needing to manually "kill" and restart the application, a feature now commonly referred to as "hot reload."

But what is a symbolic link exactly? It comes from programming and I often liken symbolic links to basic redirects but with greater stability. However, not every package needs a place in .bin. Packages like nodemon, webpack, gulp, eslint and create-vue are found in .bin because they need to be executed. On the other hand, packages like animate.css, swiper and express operate at the application layer, so you won't find them in .bin after installation. How does npm determine whether a package is executable or not? It's simple: by using the bin property in your package.json to specify the executable path. If your package is executable, you can set it accordingly. Let's take a look at prettier's package.json file

With the release of Node.js 22, this feature has been stabilized, so this warning no longer appears. While you could previously use a third-party tool like nodemon, this update removes the need for a dependency by adding it directly to Node.js core.

nodemon - enables automatic reload of your server after code change docs

Then, install nodemon (in the VSCode terminal also), which, to my understanding, automatically refreshes the server you'll be sending requests to, whenever you make a change. Using plain node.js, you'd have to manually stop and restart the server after every change.

That's already pretty good, but as you already know it's a PITA to work with this during development. You will have to rebuild your Docker images whenever you change your code, even though your apps will probably support hot-reloading out of the box (or with something like Nodemon if not).

Amazon Linux 2023 stands as a reliable choice for developers and system administrators. However, users may face a hiccup: Supervisor, is absent from the default RPM packages. This omission poses a challenge for efficiently managing and monitoring processes on Amazon Linux instances.

Can the software resume after being restarted? If yes, the problem then becomes launching the software at boot, whether as a service or using things like supervisor.[0]

- [0]: https://github.com/Supervisor/supervisor

What I went with was having both a web server (Apache/Nginx) and PHP-FPM in the same container image, held together by Supervisor: http://supervisord.org/

In my case, the Dockerfile looks a bit like the following:

  # Whatever base web server image you want, Debian/Ubuntu based here

As you can see there are several methods of running devpi server including cron, launchd (OSX service), nginx, Windows service, and supervisord. It also has a systemd service file which we can use to manage the service easily as Ubuntu uses it for primary service management. First off though we're going to need a proxy script to ensure that devpi is running in the virtual environment:

If it's a linux box you can make it a systemctl service, or you could use http://supervisord.org/.

I used supervisord to start my server and the cloud SQL proxy within the same container. That should work for your use case too.

I convinced (previous) $dayjob to use it. It (nix) kind of hung around in the background with the team that used haskell for awhile, but became prime time when we needed to support a range of VMs running within client infrastructure that were in reality just running various python scripts under supervisord (http://supervisord.org/). The range of client machines (redhat, centos, debian, ubuntu all of different releases) with differing versions of python and supervisord were driving our support and devops teams crazy (but in a weird way - they thought they were being productive, and really enjoyed tweaking things to work with additional varieties of os...). Additionally, having to work around some minor pain points of supervisord (adding and removing config files and not interrupting running services) lead to the realisation that there was a perfectly good service manager at the bottom of the modern versions of these systems (systemd) and that nixos was just a nix wrapper around this systemd and it would only restart what actually changed...

Here's more information about the configuration file format, in case anyone is curious: http://supervisord.org/configuration.html

My problem is that it's not always immediately clear how software that would normally run as a systemd service could be launched in the foreground instead. It usually takes a bit of digging around.

This post is structured as follows: The first chapter Requirements and Design, describes the requirements for such an application, defines its processes, breaks it down into logical components, and proposes a data model. The second chapter Implementation, provides an introduction to key implementation issues, such as implementing asynchronous tasks and LDAP authentication. It also showcases the usage of Docker with Python SDK in the project, including network configuration, and describes the deployment configuration using supervisord. The final chapter summarizes the efforts and provides links to the code repositories.

I have set up supervisord running cron job. However based on the discussion in supervisord GitHub, it is not possible to redirect cron's spawned command output to supervisord.