flake: exclude all non-go files

...mainly due to arbitrarily failing ci builds, as this doesn't appear
to affect local builds/nix builds on remote builders, just fresh builds
in the ci.
the explanation for why this is happening might be that certain package
VCS's don't allow many/frequent connections from IP ranges other than
GOPROXY's (Google's).
that is sheer speculation, though.
however, it is still true that there are "no" failed ci builds with
GOPROXY env var set to its default value (left untouched), which does
indeed indicate that the above mentioned might be the root cause of the
issue after all.

this commit reverts:
    * f3e481395e
and partially reverts:
    * 14ba7b18bf

GOPROXY=direct has been kept for `nix-shell`/`nix develop` environments
as that is not where it poses an issue.

.drone.starlark

@@ -7,9 +7,6 @@ def main(ctx):
 			"kind": "pipeline",
 			"type": "docker",
 			"name": "golangci-lint",
-			"environment": {
-				"GOPROXY": "direct"
-			},
 			"steps": [
 				{
 					"name": "golangci-lint",
@@ -33,9 +30,6 @@ def main(ctx):
 			"node": {
 				"r": "w"
 			},
-			"environment": {
-				"GOPROXY": "direct"
-			},
 			"steps": [
 				{
 					"name": "pull nix",
@@ -282,9 +276,6 @@ def main(ctx):
 			"node": {
 				"r": "w"
 			},
-			"environment": {
-				"GOPROXY": "direct"
-			},
 			"steps": [
 				{
 					"name": "pull archlinux",
@@ -362,9 +353,6 @@ def main(ctx):
 			"node": {
 				"r": "w"
 			},
-			"environment": {
-				"GOPROXY": "direct"
-			},
 			"steps": [
 				{
 					"name": "pull fedora",

.golangci.yml

@@ -34,10 +34,8 @@ linters:
     - ineffassign
     # - ifshort
     - misspell
-    - prealloc
+    # - prealloc #  disable for now as it might be premature optimisation
     - revive
-    - rowserrcheck
-    - sqlclosecheck
     - unconvert
     - unparam
     - varcheck

.pre-commit-config.yaml

@@ -45,13 +45,10 @@ repos:
   - repo: https://github.com/dnephin/pre-commit-golang
     rev: v0.5.0
     hooks:
-      - id: go-vet
+      - id: go-mod-tidy
       - id: go-unit-tests
-      - id: go-cyclo
-        args: [-over=15]
       - id: golangci-lint
       - id: go-build
-      - id: go-mod-tidy
   - repo: local
     hooks:
       - id: nix-build

flake.lock

@@ -16,6 +16,21 @@
         "type": "github"
       }
     },
+    "nix-filter": {
+      "locked": {
+        "lastModified": 1653590866,
+        "narHash": "sha256-E4yKIrt/S//WfW5D9IhQ1dVuaAy8RE7EiCMfnbrOC78=",
+        "owner": "numtide",
+        "repo": "nix-filter",
+        "rev": "3e81a637cdf9f6e9b39aeb4d6e6394d1ad158e16",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "nix-filter",
+        "type": "github"
+      }
+    },
     "nixgl": {
       "inputs": {
         "nixpkgs": [
@@ -55,6 +70,7 @@
     "root": {
       "inputs": {
         "flake-compat": "flake-compat",
+        "nix-filter": "nix-filter",
         "nixgl": "nixgl",
         "nixpkgs": "nixpkgs"
       }

flake.nix

@@ -10,11 +10,17 @@
       flake = false;
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    nix-filter = {
+      url = "github:numtide/nix-filter";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  outputs = { self, nixgl, nixpkgs, ... }:
+  outputs = { self, nixgl, nix-filter, nixpkgs, ... }:
     let
 
+      projname = "go-xkcdreader";
+
       # to work with older version of flakes
       lastModifiedDate =
         self.lastModifiedDate or self.lastModified or "19700101";
@@ -39,6 +45,10 @@
       });
     in
     rec {
+      formatter = forAllSystems (system:
+        nixpkgsFor.${system}.nixpkgs-fmt
+      );
+
       packages = forAllSystems (system:
         let
           pkgs = nixpkgsFor.${system};
@@ -46,7 +56,7 @@
         in
         rec {
           go-xkcdreader = with pkgs; buildGoModule rec {
-            pname = "go-xkcdreader";
+            pname = "${projname}";
             buildInputs = [
               gcc
               libglvnd # instead of libGL
@@ -67,7 +77,7 @@
             nativeBuildInputs = [ pkgconfig ];
 
             overrideModAttrs = _: {
-              GOPROXY = "direct";
+              # GOPROXY = "direct";
             };
 
             inherit version;
@@ -83,15 +93,35 @@
 
             modSha256 = lib.fakeSha256;
             # dont't forget to update vendorSha256 whenever go.mod or go.sum change
-            vendorSha256 = "sha256-gaIoacCs0PcvmFW8dQOFUb9KU1u6KUiFmGQ/ERcVwjc=";
+            vendorSha256 = "sha256-LvdcTbj8cFlaIBsq1VLfLF2Tu9HiZzGO8igD766nMLE=";
 
             # In 'nix develop', we don't need a copy of the source tree
             # in the Nix store.
-            src = lib.cleanSource ./.;
+            src = nix-filter.lib.filter {
+              root = lib.cleanSource ./.;
+              exclude = [
+                ./flake.nix
+                ./flake.lock
+                ./default.nix
+                ./shell.nix
+
+                ./check-fmt
+                ./README.md
+                ./LICENSE
+
+                ./.drone.starlark
+                ./.envrc
+                ./.example.vimrc
+                ./.gitattributes
+                ./.gitignore
+                ./.golangci.yml
+                ./.pre-commit-config.yaml
+              ];
+            };
 
             meta = {
               description = "an offline-capable xkcd webcomic reader written in Go";
-              homepage = "https://git.dotya.ml/wanderer/go-xkcdreader";
+              homepage = "https://git.dotya.ml/wanderer/${projname}";
               license = lib.licenses.gpl3;
               maintainers = [ "wanderer" ];
               platforms = lib.platforms.linux ++ lib.platforms.darwin;
@@ -105,7 +135,7 @@
         go-xkcdreader = {
           type = "app";
           program =
-            "${self.packages.${system}.go-xkcdreader}/bin/go-xkcdreader";
+            "${self.packages.${system}.${projname}}/bin/${projname}";
         };
         default = go-xkcdreader;
       });
@@ -138,7 +168,7 @@
             nix-store --query --references $(nix-instantiate shell.nix) | \
               xargs nix-store --realise | \
               xargs nix-store --query --requisites | \
-              cachix push go-xkcdreader
+              cachix push ${projname}
           '';
           add-license = pkgs.writeShellScriptBin "add-license" ''
             go run github.com/google/addlicense@v1.0.0 -v \
@@ -149,7 +179,7 @@
         {
           default = with pkgs; mkShell
             {
-              name = "go-xkcdreader-" + version;
+              name = "${projname}-" + version;
 
               GOFLAGS = "-buildmode=pie -trimpath -mod=readonly -modcacherw";
               GOLDFLAGS = "-s -w -X cmd.version=${version}";