tasks: convert some of the enterShell into tasks

devenv.nix

@@ -210,12 +210,6 @@ EOF
     '';
   };
 
-
-  tasks."devenv:sleep3".exec = "sleep 3";
-  tasks."devenv:sleep".exec = "sleep 5";
-  tasks."devenv:sleep".depends = [ "devenv:sleep3" ];
-  tasks."devenv:enterShell".depends = [ "devenv:sleep" ];
-
   pre-commit.hooks = {
     nixpkgs-fmt.enable = true;
     #shellcheck.enable = true;

devenv/init/devenv.nix

@@ -26,6 +26,12 @@
     git --version
   '';
 
+  # https://devenv.sh/tasks/
+  # tasks = {
+  #   "myproj:setup".exec = "mytool build";
+  #   "devenv:enterShell".depends = ["myproj:setup"];
+  # };
+
   # https://devenv.sh/tests/
   enterTest = ''
     echo "Running tests"

docs/tasks.md

@@ -8,19 +8,32 @@ Tasks allow you to form dependencies between commands, executed in parallel.
 {
   tasks."myapp:hello" = {
     exec = ''echo "Hello, world!"'';
-    desc = "hello world in bash";
   };
 }
 ```
 
 ```shell-session
 $ devenv tasks run hello
-• Building shell ...
-• Entering shell ...
-Hello, world!
+Hello, world
 $
 ```
 
+## enterShell / enterTest
+
+If you'd like the tasks to run as part of the `enterShell` or `enterTest`:
+
+```nix title="devenv.nix"
+{ pkgs, lib, config, ... }:
+
+{
+  tasks = {
+    "bash:hello".exec = "echo 'Hello world from bash!'";
+    "devenv:enterShell".depends = [ "bash:hello" ];
+    "devenv:enterTest".depends = [ "bash:hello" ];
+  };
+}
+```
+
 ## Using your favourite language
 
 Tasks can also reference scripts and depend on other tasks, for example when entering the shell:
@@ -31,25 +44,65 @@ Tasks can also reference scripts and depend on other tasks, for example when ent
 {
   tasks = {
     "python:hello"" = {
-      exec = ''print("Hello world from Python!")'';
+      exec = ''
+        print("Hello world from Python!")
+      '';
       package = config.languages.python.package;
     };
-    "bash:hello" = {
-      exec = "echo 'Hello world from bash!'";
-      depends = [ "python:hello" ];
-    };
-    "devenv:enterShell".depends = [ "bash:hello" ];
   };
 }
 ```
 
 ```shell-session
 $ devenv shell
-• Building shell ...
-• Entering shell ...
 ...
-$
 ```
 
 
-`status`
+## Avoiding running expensive `exec` via `status` check
+
+If you define a `status` command, it will be executed first and if it returns `0`, `exec` will be skipped.
+
+```nix title="devenv.nix"
+{ pkgs, lib, config, ... }:
+
+{
+  tasks = {
+    "myapp:migrations" = {
+      exec = "db-migrate";
+      status = "db-needs-migrations";
+    };
+  };
+}
+```
+
+## Inputs / Outputs
+
+Tasks support passing inputs and produce outputs, both as JSON objects:
+
+- `$DEVENV_TASK_INPUTS`: JSON object serializing `tasks."myapp:mytask".inputs`.
+- `$DEVENV_TASK_OUTPUTS`: a writable file with tasks' outputs in JSON.
+- `$DEVENV_TASKS_OUTPUTS`: JSON object with dependent tasks as keys and their outputs as values.
+
+```nix title="devenv.nix"
+{ pkgs, lib, config, ... }:
+
+{
+  tasks = {
+    "myapp:mytask" = {
+      exec = ''
+        echo $DEVENV_TASK_INPUTS > $DEVENV_ROOT/inputs.json
+        echo '{ "output" = 1; }' > $DEVENV_TASK_OUTPUTS
+        echo $DEVENV_TASKS_OUTPUTS > $DEVENV_ROOT/outputs.json
+      '';
+      inputs = {
+        value = 1;
+      };
+    };
+  };
+}
+```
+
+## SDK
+
+See [xxx](xxx) for a proposal how defining tasks in your favorite language would look like.

src/modules/integrations/pre-commit.nix

@@ -20,11 +20,14 @@
 
   config = lib.mkIf ((lib.filterAttrs (id: value: value.enable) config.pre-commit.hooks) != { }) {
     ci = [ config.pre-commit.run ];
-    enterTest = ''
-      pre-commit run -a
-    '';
     # Add the packages for any enabled hooks at the end to avoid overriding the language-defined packages.
     packages = lib.mkAfter ([ config.pre-commit.package ] ++ (config.pre-commit.enabledPackages or [ ]));
-    enterShell = config.pre-commit.installationScript;
+    tasks = {
+      # TODO: split installation script into status + exec
+      "devenv:pre-commit:install".exec = config.pre-commit.installationScript;
+      "devenv:pre-commit:run".exec = "pre-commit run -a";
+      "devenv:enterShell".depends = [ "devenv:pre-commit:install" ];
+      "devenv:enterTest".depends = [ "devenv:pre-commit:run" ];
+    };
   };
 }

src/modules/tasks.nix

@@ -97,7 +97,7 @@ in
         description = "Runs when entering the test environment";
       };
     };
-    #enterShell = "devenv tasks run devenv:enterShell";
-    #enterTest = "devenv tasks run devenv:enterTest";
+    enterShell = "devenv tasks run devenv:enterShell";
+    enterTest = "devenv tasks run devenv:enterTest";
   };
 }