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devenv

devenv devlog: Processes are now tasks

Domen Kožar
Domen Kožar

Building on the task runner, devenv now exposes all processes as tasks named devenv:processes:<name>.

Now you can run tasks before or after a process runs - addressing a frequently requested feature for orchestrating the startup sequence.

Usage

Section titled “Usage”

Execute setup tasks before the process starts

Section titled “Execute setup tasks before the process starts”
devenv.nix
{
  processes.backend = {
    exec = "cargo run --release";
  };


  tasks."db:migrate" = {
    exec = "diesel migration run";
    before = [ "devenv:processes:backend" ];
  };
}

When you run devenv up or the individual process task, migrations run first.

Run cleanup after the process stops

Section titled “Run cleanup after the process stops”
devenv.nix
{
  processes.app = {
    exec = "node server.js";
  };


  tasks."app:cleanup" = {
    exec = ''
      rm -f ./server.pid
      rm -rf ./tmp/*
    '';
    after = [ "devenv:processes:app" ];
  };
}

Implementation

Section titled “Implementation”

Under the hood, process-compose now runs processes through devenv-tasks run --mode all devenv:processes:<name> instead of executing them directly. This preserves all existing process functionality while adding task capabilities.

The --mode all flag ensures that both before and after tasks are executed, maintaining the expected lifecycle behavior.

What’s next?

Section titled “What’s next?”

Future work on process dependencies (#2037) will also address native health check support (process-compose#371), eliminating the need for manual polling scripts.

Domen