feat: Add crowdsec module

pkgs/crowdsec/firewall-bouncer.nix

@@ -0,0 +1,26 @@
+{
+  lib,
+  sources,
+  buildGoModule,
+  envsubst,
+  coreutils,
+}:
+let
+  envsubstBin = lib.getExe envsubst;
+in
+buildGoModule {
+  inherit (sources.crowdsec-firewall-bouncer) pname version src;
+
+  vendorHash = "sha256-7Jxvg8UEjUxnIz1llvXyI2AefJ31OVdNzhWD/C8wU/Y=";
+
+  postInstall = ''
+    mkdir -p $out/lib/systemd/system
+
+    CFG=/var/lib/crowdsec/config BIN=$out/bin/cs-firewall-bouncer ${envsubstBin} \
+      -i ./config/crowdsec-firewall-bouncer.service \
+      -o $out/lib/systemd/system/crowdsec-firewall-bouncer.service
+
+    substituteInPlace $out/lib/systemd/system/crowdsec-firewall-bouncer.service \
+      --replace-fail /bin/sleep ${coreutils}/bin/sleep
+  '';
+}