workbench: empty the exit_code file before a supervisord program is s…

…tarted

nix/workbench/backend/supervisor-conf.nix

@@ -14,15 +14,13 @@ let
   # may run in the most unexpected places where we can't asume what is or isn't
   # included in $PATH. Just make sure pkgs.bashInteractive is in the nix store.
   sh = "${pkgs.bashInteractive}/bin/sh";
-  # Same as above for `sh` applies for pkgs.coreutils.
-  touch = "${pkgs.coreutils}/bin/touch";
   # We can't obtain the exit codes using `supervisorctl status`, it returns zero
   # when RUNNING and non-zero for STOPPED, EXITED, FATAL, and UNKNOWN, so as we
   # are not using any "autorestart" like functionality supervisord programs are
   # echoing their exit code after the script to a file named `exit_code` that is
-  # created empty just before starting the script.
+  # created and/or emptied before every script run.
   # Warning: This command assumes the "directory" is set correctly.
-  command = "${sh} -c \"${touch} ./exit_code; ./start.sh; echo \"$?\" > ./exit_code\"";
+  command = "${sh} -c \":> ./exit_code; ./start.sh; echo \"$?\" > ./exit_code\"";
   ##
   ## supervisorConf :: SupervisorConf
   ##

nix/workbench/service/healthcheck.nix

@@ -0,0 +1,41 @@
+{ pkgs
+, runJq
+, backend
+, profile
+, nodeSpecs
+}:
+
+with pkgs.lib;
+
+let
+  ##
+  ## generator-service :: (TracerConfig, NixosServiceConfig, Config, StartScript)
+  ##
+  healthcheck-service =
+    (nodeSpecs:
+    let
+      bashInteractive = pkgs.bashInteractive;
+      coreutils       = pkgs.coreutils;
+      supervisor      = pkgs.supervisor;
+    in {
+      startupScript = rec {
+        JSON = pkgs.writeScript "startup-healthcheck.sh" value;
+        value = ''
+          #!${bashInteractive}/bin/sh
+
+          # Store the entrypoint env vars for debugging purposes
+          ${coreutils}/bin/env > /local/healthcheck.env
+
+          # Only needed for "exec" ?
+          if test "''${TASK_DRIVER}" = "exec"
+          then
+            cd "''${TASK_WORKDIR}"
+          fi
+
+          sleep 100000
+          '';
+      };
+    })
+    nodeSpecs.value;
+in
+  { inherit healthcheck-service; }