pkgs: add morph, a mattermost migration tool

this is preliminary work for migrating mattermost from mysql to
postgresql.

This tool is specific to mattermost, but at least it's easy enough to
build. I'm not sure if it makes sense to upstream, but I guess we can
keep it around here.

pkgs/default.nix

@@ -13,6 +13,10 @@ let
       buildGoModule = unstable.buildGo122Module;
     };
 
+    morph = callPackage ./morph.nix {
+      buildGoModule = unstable.buildGo122Module;
+    };
+
     forgejo = callPackage ./forgejo {
       buildGoModule = unstable.buildGo122Module;
     };

pkgs/morph.nix

@@ -0,0 +1,33 @@
+{ buildGoModule
+, fetchFromGitHub
+}:
+
+buildGoModule rec {
+  pname = "mattermost-morph";
+  version = "1.1.0";
+
+  src = fetchFromGitHub {
+    owner = "mattermost";
+    repo = "morph";
+    rev = "v${version}";
+    hash = "sha256-Orh/a9OlUVIlDdLXRpDAnHUmWRiM1N2oO+dijbuJzx8=";
+  };
+
+  vendorHash = null;
+
+  subPackages = [ "cmd/morph" ];
+
+  tags = [ "production" ];
+
+  ldflags = [
+    "-s"
+    "-w"
+    "-X github.com/mattermost/mattermost/server/public/model.Version=${version}"
+    "-X github.com/mattermost/mattermost/server/public/model.BuildNumber=${version}-nixpkgs"
+    "-X github.com/mattermost/mattermost/server/public/model.BuildDate=1970-01-01"
+    "-X github.com/mattermost/mattermost/server/public/model.BuildHash=v${version}"
+    "-X github.com/mattermost/mattermost/server/public/model.BuildHashEnterprise=none"
+    "-X github.com/mattermost/mattermost/server/public/model.BuildEnterpriseReady=false"
+  ];
+
+}