nix: compile go test binaries for e2e tests in nix

.github/workflows/e2e_openssl.yml

@@ -64,7 +64,7 @@ jobs:
           cat ./workspace/just.perf | tee -a "${GITHUB_STEP_SUMMARY}"
       - name: E2E Test
         run: |
-          env K8S_NAMESPACE=$(cat ./workspace/just.namespace) go test -v -count=1 -tags e2e ./e2e/openssl
+          env K8S_NAMESPACE=$(cat ./workspace/just.namespace) nix shell .#nunki.e2e --command openssl.test
       - name: Undeploy
         if: always() && inputs.skip-undeploy != 'true'
         run: |

packages/by-name/buildGoTest/package.nix

@@ -0,0 +1,79 @@
+{ buildGoModule }:
+args':
+let
+  args = args' // { "doCheck" = false; };
+in
+buildGoModule ({
+  # copy of buildGoModule.buildPhase with the following changes:
+  # - use `go test -c -o $GOPATH/bin/` instead of `go install` to build the binary of a test package
+  # original:
+  # https://github.com/NixOS/nixpkgs/blob/c44815411ae47dd8bbbb92d60c3a83abff28a9f3/pkgs/build-support/go/module.nix#L188-L266
+  buildPhase = ''
+    runHook preBuild
+
+    exclude='\(/_\|examples\|Godeps\|testdata'
+    if [[ -n "$excludedPackages" ]]; then
+      IFS=' ' read -r -a excludedArr <<<$excludedPackages
+      printf -v excludedAlternates '%s\\|' "''${excludedArr[@]}"
+      excludedAlternates=''${excludedAlternates%\\|} # drop final \| added by printf
+      exclude+='\|'"$excludedAlternates"
+    fi
+    exclude+='\)'
+
+    buildGoDir() {
+      local cmd="$1" dir="$2"
+
+      . $TMPDIR/buildFlagsArray
+
+      declare -a flags
+      flags+=($buildFlags "''${buildFlagsArray[@]}")
+      flags+=(''${tags:+-tags=''${tags// /,}})
+      flags+=(''${ldflags:+-ldflags="$ldflags"})
+      flags+=("-p" "$NIX_BUILD_CORES")
+
+      if [ "$cmd" = "test" ]; then
+        flags+=(-vet=off)
+        flags+=($checkFlags)
+      fi
+
+      local OUT
+      if ! OUT="$(go $cmd -c -o $GOPATH/bin/ "''${flags[@]}" $dir 2>&1)"; then
+        if ! echo "$OUT" | grep -qE '(no( buildable| non-test)?|build constraints exclude all) Go (source )?files'; then
+          echo "$OUT" >&2
+          return 1
+        fi
+      fi
+      if [ -n "$OUT" ]; then
+        echo "$OUT" >&2
+      fi
+      return 0
+    }
+
+    getGoDirs() {
+      local type;
+      type="$1"
+      if [ -n "$subPackages" ]; then
+        echo "$subPackages" | sed "s,\(^\| \),\1./,g"
+      else
+        find . -type f -name \*$type.go -exec dirname {} \; | grep -v "/vendor/" | sort --unique | grep -v "$exclude"
+      fi
+    }
+
+    if (( "''${NIX_DEBUG:-0}" >= 1 )); then
+      buildFlagsArray+=(-x)
+    fi
+
+    if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
+      declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
+    else
+      touch $TMPDIR/buildFlagsArray
+    fi
+    if [ -z "$enableParallelBuilding" ]; then
+        export NIX_BUILD_CORES=1
+    fi
+    for pkg in $(getGoDirs ""); do
+      echo "Building subPackage $pkg"
+      buildGoDir test "$pkg"
+    done
+  '';
+} // args)

packages/by-name/nunki/package.nix

@@ -1,8 +1,22 @@
 { lib
 , buildGoModule
+, buildGoTest
 , genpolicy-msft
 , genpolicy ? genpolicy-msft
+, nunki
 }:
+let
+  e2e = buildGoTest rec {
+    inherit (nunki) version src proxyVendor vendorHash prePatch CGO_ENABLED;
+    pname = "${nunki.pname}-e2e";
+
+    tags = [ "e2e" ];
+
+    ldflags = [ "-w" ];
+
+    subPackages = [ "e2e/openssl" ];
+  };
+in
 
 buildGoModule rec {
   pname = "nunki";
@@ -68,5 +82,8 @@ buildGoModule rec {
     # rename the cli binary to nunki
     mv "$cli/bin/cli" "$cli/bin/nunki"
   '';
+
+  passthru.e2e = e2e;
+
   meta.mainProgram = "nunki";
 }