From 72a510c26badf4d5c421673b21c859d7c9d2c2c4 Mon Sep 17 00:00:00 2001
From: Sander van der Burg <svanderburg@gmail.com>
Date: Wed, 3 Mar 2021 21:49:38 +0100
Subject: [PATCH] Initial version of a declarative fcron

---
 example-deployments/services/processes.nix |  8 +++++-
 services-agnostic/constructors.nix         |  7 ++++-
 services-agnostic/fcron/declarative.nix    | 32 ++++++++++++++++++++++
 services-agnostic/fcron/default.nix        | 18 +++++++++---
 4 files changed, 59 insertions(+), 6 deletions(-)
 create mode 100644 services-agnostic/fcron/declarative.nix

diff --git a/example-deployments/services/processes.nix b/example-deployments/services/processes.nix
index 543b1ae..7a3d1fd 100644
--- a/example-deployments/services/processes.nix
+++ b/example-deployments/services/processes.nix
@@ -123,7 +123,13 @@ rec {
   };
 
   fcron = {
-    pkg = constructors.fcron {};
+    pkg = constructors.declarativeFcron {
+      fcrontabPerUser = {
+        systab = ''
+          @ 1 echo hello >> /tmp/hello
+        '';
+      };
+    };
 
     requiresUniqueIdsFor = [ "uids" "gids" ];
   };
diff --git a/services-agnostic/constructors.nix b/services-agnostic/constructors.nix
index e96ff9e..d7a5776 100644
--- a/services-agnostic/constructors.nix
+++ b/services-agnostic/constructors.nix
@@ -63,7 +63,12 @@ in
 
   fcron = import ./fcron {
     inherit createManagedProcess stateDir spoolDir runtimeDir tmpDir forceDisableUserChange;
-    inherit (pkgs) writeTextFile fcron;
+    inherit (pkgs) lib writeTextFile fcron;
+  };
+
+  declarativeFcron = import ./fcron/declarative.nix {
+    inherit createManagedProcess stateDir spoolDir runtimeDir tmpDir forceDisableUserChange;
+    inherit (pkgs) lib writeTextFile fcron;
   };
 
   hydra-evaluator = import ./hydra/hydra-evaluator.nix {
diff --git a/services-agnostic/fcron/declarative.nix b/services-agnostic/fcron/declarative.nix
new file mode 100644
index 0000000..a1045a9
--- /dev/null
+++ b/services-agnostic/fcron/declarative.nix
@@ -0,0 +1,32 @@
+{createManagedProcess, writeTextFile, lib, fcron, stateDir, runtimeDir, tmpDir, spoolDir, forceDisableUserChange}:
+
+{ instanceSuffix ? ""
+, instanceName ? "fcron${instanceSuffix}"
+, initialize ? ""
+, fcrontabPerUser
+}:
+
+let
+  fcronSpoolDir = "${spoolDir}/${instanceName}";
+in
+import ./default.nix {
+  inherit createManagedProcess writeTextFile lib fcron stateDir runtimeDir tmpDir spoolDir forceDisableUserChange;
+} {
+  inherit instanceSuffix instanceName;
+
+  initialize = ''
+    ${lib.concatMapStrings (user:
+      let
+        fcrontab = builtins.getAttr user fcrontabPerUser;
+        fcrontabFile = writeTextFile {
+          name = "fcrontab-${user}";
+          text = fcrontab;
+        };
+      in
+      ''
+        cp ${fcrontabFile} ${fcronSpoolDir}/${user}.orig
+      ''
+    ) (builtins.attrNames fcrontabPerUser)}
+    ${initialize}
+  '';
+}
diff --git a/services-agnostic/fcron/default.nix b/services-agnostic/fcron/default.nix
index 92e374c..41585fc 100644
--- a/services-agnostic/fcron/default.nix
+++ b/services-agnostic/fcron/default.nix
@@ -1,5 +1,5 @@
-{createManagedProcess, writeTextFile, fcron, stateDir, runtimeDir, tmpDir, spoolDir, forceDisableUserChange}:
-{instanceSuffix ? "", instanceName ? "fcron${instanceSuffix}"}:
+{createManagedProcess, writeTextFile, lib, fcron, stateDir, runtimeDir, tmpDir, spoolDir, forceDisableUserChange}:
+{instanceSuffix ? "", instanceName ? "fcron${instanceSuffix}", initialize ? ""}:
 
 let
   fcronSpoolDir = "${spoolDir}/${instanceName}";
@@ -24,11 +24,19 @@ in
 createManagedProcess {
   name = instanceName;
   inherit instanceName;
+
   initialize = ''
-    mkdir -p ${fcronSpoolDir}
+    mkdir -p ${fcronEtcDir}
+    cp ${configFile} ${fcronEtcDir}/fcron.conf
+    chmod 644 ${fcronEtcDir}/fcron.conf
+    ${lib.optionalString (!forceDisableUserChange) ''
+      chown root:${group} ${fcronEtcDir}/fcron.conf
+    ''}
+    ${initialize}
   '';
+
   process = "${fcron}/bin/fcron";
-  args = [ "--configfile" configFile ];
+  args = [ "--configfile" "${fcronEtcDir}/fcron.conf" ];
   foregroundProcessExtraArgs = [ "--foreground" "--nosyslog" ];
   daemonExtraArgs = [ "--background" ];
 
@@ -39,6 +47,8 @@ createManagedProcess {
     users = {
       "${user}" = {
         inherit group;
+        homeDir = fcronSpoolDir;
+        createHomeDir = true;
         description = "Fcron user";
       };
     };