switch databasebackup contract to new contract style

modules/blocks/postgresql.nix

@@ -52,35 +52,23 @@ in
 
     databasebackup = lib.mkOption {
       description = ''
-        Backup configuration. This is an output option.
-
-        Use it to initialize a block implementing the "backup" contract.
-        For example, with the restic block:
-
-        ```
-        shb.restic.instances."postgresql" = {
-          request = config.shb.postgresl.backup;
-          settings = {
-            enable = true;
-          };
-        };
-        ```
+        Backup configuration.
       '';
 
-      type = contracts.databasebackup.request;
-
-      default = {
-        user = "postgres";
+      type = lib.types.submodule {
+        options = contracts.databasebackup.mkRequester {
+          user = "postgres";
 
-        backupName = "postgres.sql";
+          backupName = "postgres.sql";
 
-        backupCmd = ''
-          ${pkgs.postgresql}/bin/pg_dumpall | ${pkgs.gzip}/bin/gzip --rsyncable
-        '';
+          backupCmd = ''
+            ${pkgs.postgresql}/bin/pg_dumpall | ${pkgs.gzip}/bin/gzip --rsyncable
+          '';
 
-        restoreCmd = ''
-          ${pkgs.gzip}/bin/gunzip | ${pkgs.postgresql}/bin/psql postgres
-        '';
+          restoreCmd = ''
+            ${pkgs.gzip}/bin/gunzip | ${pkgs.postgresql}/bin/psql postgres
+          '';
+        };
       };
     };
 
@@ -181,5 +169,10 @@ in
             (upgrade-script 15 16)
           ];
         }
+        {
+          # Seems superfluous but otherwise we get:
+          # The option `shb.postgresql.databasebackup' was accessed but has no value defined.
+          shb.postgresql.databasebackup = {};
+        }
       ]);
 }

modules/blocks/restic.nix

@@ -137,17 +137,7 @@ in
       description = "Databases to backup following the [database backup contract](./contracts-databasebackup.html).";
       default = {};
       type = attrsOf (submodule ({ name, config, ... }: {
-        options = {
-          request = mkOption {
-            description = ''
-              Request part of the backup contract.
-
-              Accepts values from a requester.
-            '';
-
-            type = contracts.databasebackup.request;
-          };
-
+        options = contracts.databasebackup.mkProvider {
           settings = mkOption {
             description = ''
               Settings specific to the Restic provider.
@@ -158,26 +148,12 @@ in
             };
           };
 
-          result = mkOption {
-            description = ''
-              Result part of the backup contract.
+          resultCfg = {
+            restoreScript = fullName name config.settings.repository;
+            restoreScriptText = "${fullName "<name>" { path = "path/to/repository"; }}";
 
-              Contains the output of the Restic provider.
-            '';
-            default = {
-              restoreScript = fullName name config.settings.repository;
-              backupService = "${fullName name config.settings.repository}.service";
-            };
-            defaultText = {
-              restoreScriptText = "${fullName "<name>" { path = "path/to/repository"; }}";
-              backupServiceText = "${fullName "<name>" { path = "path/to/repository"; }}.service";
-            };
-            type = contracts.databasebackup.result {
-              restoreScript = fullName name config.settings.repository;
-              backupService = "${fullName name config.settings.repository}.service";
-              restoreScriptText = "${fullName "<name>" { path = "path/to/repository"; }}";
-              backupServiceText = "${fullName "<name>" { path = "path/to/repository"; }}.service";
-            };
+            backupService = "${fullName name config.settings.repository}.service";
+            backupServiceText = "${fullName "<name>" { path = "path/to/repository"; }}.service";
           };
         };
       }));

modules/contracts/databasebackup.nix

@@ -1,87 +1,160 @@
-{ lib, ... }:
+{ pkgs, lib, ... }:
 let
-  inherit (lib) mkIf mkOption literalExpression;
-  inherit (lib.types) anything submodule str;
+  inherit (lib) mkOption literalExpression literalMD optionalAttrs optionalString;
+  inherit (lib.types) submodule str;
+
+  shblib = pkgs.callPackage ../../lib {};
+  inherit (shblib) anyNotNull;
 in
 {
-  request = submodule {
-    options = {
-      user = mkOption {
-        description = ''
-          Unix user doing the backups.
-
-          This should be an admin user having access to all databases.
-        '';
-        type = str;
-        example = "postgres";
-      };
+  mkRequest =
+    { user ? "root",
+      userText ? null,
+      backupName ? "dump",
+      backupNameText ? null,
+      backupCmd ? "",
+      backupCmdText ? null,
+      restoreCmd ? "",
+      restoreCmdText ? null,
+    }: mkOption {
+      description = ''
+        Request part of the backup contract.
 
-      backupName = mkOption {
-        description = "Name of the backup in the repository.";
-        type = str;
-        default = "dump";
-        example = "postgresql.sql";
-      };
+        Options set by the requester module
+        enforcing how to backup files.
+      '';
 
-      backupCmd = mkOption {
-        description = "Command that produces the database dump on stdout.";
-        type = str;
-        example = literalExpression ''
-          ''${pkgs.postgresql}/bin/pg_dumpall | ''${pkgs.gzip}/bin/gzip --rsyncable
-        '';
+      default = {
+        inherit user backupName backupCmd restoreCmd;
       };
 
-      restoreCmd = mkOption {
-        description = "Command that reads the database dump on stdin and restores the database.";
-        type = str;
-        example = literalExpression ''
-          ''${pkgs.gzip}/bin/gunzip | ''${pkgs.postgresql}/bin/psql postgres
-        '';
+      defaultText = optionalString (anyNotNull [
+        userText
+        backupNameText
+        backupCmdText
+        restoreCmdText
+      ]) (literalMD ''
+      {
+        user = ${if userText != null then userText else user};
+        backupName = ${if backupNameText != null then backupNameText else backupName};
+        backupCmd = ${if backupCmdText != null then backupCmdText else backupCmd};
+        restoreCmd = ${if restoreCmdText != null then restoreCmdText else restoreCmd};
+      }
+      '');
+
+      type = submodule {
+        options = {
+          user = mkOption {
+            description = ''
+              Unix user doing the backups.
+
+              This should be an admin user having access to all databases.
+            '';
+            type = str;
+            example = "postgres";
+            default = user;
+          } // optionalAttrs (userText != null) {
+            defaultText = literalMD userText;
+          };
+
+          backupName = mkOption {
+            description = "Name of the backup in the repository.";
+            type = str;
+            example = "postgresql.sql";
+            default = backupName;
+          } // optionalAttrs (backupNameText != null) {
+            defaultText = literalMD backupNameText;
+          };
+
+          backupCmd = mkOption {
+            description = "Command that produces the database dump on stdout.";
+            type = str;
+            example = literalExpression ''
+              ''${pkgs.postgresql}/bin/pg_dumpall | ''${pkgs.gzip}/bin/gzip --rsyncable
+            '';
+            default = backupCmd;
+          } // optionalAttrs (backupCmdText != null) {
+            defaultText = literalMD backupCmdText;
+          };
+
+          restoreCmd = mkOption {
+            description = "Command that reads the database dump on stdin and restores the database.";
+            type = str;
+            example = literalExpression ''
+              ''${pkgs.gzip}/bin/gunzip | ''${pkgs.postgresql}/bin/psql postgres
+            '';
+            default = restoreCmd;
+          } // optionalAttrs (restoreCmdText != null) {
+            defaultText = literalMD restoreCmdText;
+          };
+        };
       };
     };
-  };
 
 
-  result = {
-    restoreScript,
+  mkResult = {
+    restoreScript ? "restore",
     restoreScriptText ? null,
-    backupService,
+    backupService ? "backup.service",
     backupServiceText ? null,
-  }: submodule {
-    options = {
-      restoreScript = mkOption {
-        description = ''
-          Name of script that can restore the database.
-          One can then list snapshots with:
-
-          ```bash
-          $ ${if restoreScriptText != null then restoreScriptText else restoreScript} snapshots
-          ```
-
-          And restore the database with:
-
-          ```bash
-          $ ${if restoreScriptText != null then restoreScriptText else restoreScript} restore latest
-          ```
-        '';
-        type = str;
-        default = restoreScript;
-        defaultText = restoreScriptText;
-      };
+  }: mkOption {
+    description = ''
+      Result part of the backup contract.
+
+      Options set by the provider module that indicates the name of the backup and restor scripts.
+    '';
+    default = {
+      inherit restoreScript backupService;
+    };
+
+    defaultText = optionalString (anyNotNull [
+      restoreScriptText
+      backupServiceText
+    ]) (literalMD ''
+    {
+      restoreScript = ${if restoreScriptText != null then restoreScriptText else restoreScript};
+      backupService = ${if backupServiceText != null then backupServiceText else backupService};
+    }
+    '');
+
+    type = submodule {
+      options = {
+        restoreScript = mkOption {
+          description = ''
+            Name of script that can restore the database.
+            One can then list snapshots with:
+
+            ```bash
+            $ ${if restoreScriptText != null then restoreScriptText else restoreScript} snapshots
+            ```
+
+            And restore the database with:
+
+            ```bash
+            $ ${if restoreScriptText != null then restoreScriptText else restoreScript} restore latest
+            ```
+          '';
+          type = str;
+          default = restoreScript;
+        } // optionalAttrs (restoreScriptText != null) {
+          defaultText = literalMD restoreScriptText;
+        };
 
-      backupService = mkOption {
-        description = ''
-          Name of service backing up the database.
+        backupService = mkOption {
+          description = ''
+            Name of service backing up the database.
 
-          This script can be ran manually to backup the database:
+            This script can be ran manually to backup the database:
 
-          ```bash
-          $ systemctl start ${if backupServiceText != null then backupServiceText else backupService}
-          ```
-        '';
-        type = str;
-        default = backupService;
-        defaultText = backupServiceText;
+            ```bash
+            $ systemctl start ${if backupServiceText != null then backupServiceText else backupService}
+            ```
+          '';
+          type = str;
+          default = backupService;
+        } // optionalAttrs (backupServiceText != null) {
+          defaultText = literalMD backupServiceText;
+        };
       };
     };
   };

modules/contracts/databasebackup/dummyModule.nix

@@ -3,7 +3,7 @@ let
   contracts = pkgs.callPackage ../. {};
 
   inherit (lib) mkOption;
-  inherit (lib.types) anything submodule;
+  inherit (lib.types) submodule;
 in
 {
   options.shb.contracts.databasebackup = mkOption {
@@ -23,24 +23,7 @@ in
     '';
 
     type = submodule {
-      options = {
-        request = mkOption {
-          description = ''
-          Options set by a requester module of the database backup contract.
-          '';
-          type = contracts.databasebackup.request;
-        };
-
-        result = mkOption {
-          description = ''
-          Options set by a provider module of the database backup contract.
-          '';
-          type = contracts.databasebackup.result {
-            restoreScript = "my_restore_script";
-            backupService = "my_backup_service.service";
-          };
-        };
-      };
+      options = contracts.databasebackup.contract;
     };
   };
 }