feat(redirections): Make it more flexible to allow temporary redirects

machines/compute01/dgsi/default.nix

@@ -187,7 +187,7 @@ in
     ];
   };
 
-  dgn-redirections.redirections."dgsi.dgnum.eu" = "profil.dgnum.eu";
+  dgn-redirections.permanent."dgsi.dgnum.eu" = "profil.dgnum.eu";
 
   services = {
     postgresql = {

machines/storage01/redirections.nix

@@ -1,6 +1,6 @@
 {
   dgn-redirections = {
-    redirections = {
+    permanent = {
       "www.lanuit.ens.fr" = "lanuit.ens.fr";
       "lanuit.ens.psl.eu" = "lanuit.ens.fr";
       "www.lanuit.ens.psl.eu" = "lanuit.ens.fr";

machines/web01/redirections.nix

@@ -14,7 +14,7 @@ in
   dgn-redirections = {
     inherit retiredHost;
 
-    redirections = {
+    permanent = {
       "calendrier.eleves.ens.fr" = "calendrier.dgnum.eu";
       "docs.beta.rz.ens.wtf" = "pads.dgnum.eu";
       "git.rz.ens.wtf" = "git.dgnum.eu";

machines/web02/cas-eleves/default.nix

@@ -126,7 +126,7 @@ in
     };
   };
 
-  dgn-redirections.redirections."cas-eleves.dgnum.eu" = "cas.eleves.ens.fr";
+  dgn-redirections.permanent."cas-eleves.dgnum.eu" = "cas.eleves.ens.fr";
 
   services = {
     postgresql = {

modules/dgn-redirections/default.nix

@@ -3,7 +3,13 @@
 let
   inherit (lib) mkOption;
 
-  inherit (lib.types) attrsOf listOf str;
+  inherit (lib.types)
+    attrsOf
+    ints
+    listOf
+    str
+    submodule
+    ;
 
   mkRetired =
     hosts:
@@ -18,19 +24,33 @@ let
       }) hosts
     );
 
-  mkRedirection = _: globalRedirect: {
+  mkPermanent = _: globalRedirect: {
     inherit globalRedirect;
 
     enableACME = true;
     forceSSL = true;
   };
 
+  mkTemporary =
+    _:
+    {
+      to,
+      code,
+      location,
+    }:
+    {
+      enableACME = true;
+      forceSSL = true;
+
+      locations.${location}.return = "${toString code} ${to}";
+    };
+
   cfg = config.dgn-redirections;
 in
 
 {
   options.dgn-redirections = {
-    redirections = mkOption {
+    permanent = mkOption {
       type = attrsOf str;
       default = { };
       description = ''
@@ -40,6 +60,57 @@ in
       '';
     };
 
+    temporary = mkOption {
+      type = attrsOf (submodule {
+        options = {
+          to = mkOption {
+            type = str;
+            description = "Target of the redirection";
+          };
+          code = mkOption {
+            type = ints.between 300 399;
+            default = 302;
+            example = 308;
+            description = ''
+              HTTP status used by the redirection. Possible usecases
+              include temporary (302, 307) redirects, keeping the request method and
+              body (307, 308), or explicitly resetting the method to GET (303).
+              See <https://developer.mozilla.org/en-US/docs/Web/HTTP/Redirections>.
+            '';
+          };
+          location = mkOption {
+            type = str;
+            default = "/";
+            description = "nginx-style location for the source of the redirection";
+          };
+        };
+      });
+      default = { };
+      example = {
+        "source.dgnum.eu" = {
+          to = "https://target.dgnum.eu/path_to_page";
+          code = 307;
+          location = "/subpath/";
+        };
+      };
+      description = ''
+        Attribute set of temporary redirections. The attribute is the source
+        domain.
+
+        For:
+        ```
+        {
+          "source.dgnum.eu" = {
+            to = "https://target.dgnum.eu/path_to_page";
+            code = 307;
+          };
+        }
+        ```
+        a 307 redirect from all the urls within the domain `source.dgnum.eu` to
+        `https://target.dgnum.eu/path_to_page` will be made.
+      '';
+    };
+
     retired = mkOption {
       type = listOf str;
       default = [ ];
@@ -59,6 +130,7 @@ in
 
   config = {
     services.nginx.virtualHosts =
-      (builtins.mapAttrs mkRedirection cfg.redirections) // (mkRetired cfg.retired);
+      (builtins.mapAttrs mkPermanent cfg.permanent // builtins.mapAttrs mkTemporary cfg.temporary)
+      // (mkRetired cfg.retired);
   };
 }