Replace telegraf with node exporter

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

packages/prometheus-fail2ban-exporter/default.nix

@@ -0,0 +1,31 @@
+{ pkgs, ... }:
+# AUTO-UPDATE: nix-update --flake prometheus-fail2ban-exporter
+pkgs.buildGoModule rec {
+  pname = "prometheus-fail2ban-exporter";
+  version = "0.10.3";
+
+  src = pkgs.fetchFromGitLab {
+    owner = "hctrdev";
+    repo = "fail2ban-prometheus-exporter";
+    rev = "v${version}";
+    hash = "sha256-CyYGY6SovnvgExB22G+LEKRDRzbDZWhWUjctJMkprYs=";
+  };
+
+  vendorHash = "sha256-ogdRXbS1EG402qlnj5SfuI/1P/Pi0+xwJrJsc6vwdds=";
+
+  env.CGO_ENABLED = 0;
+
+  ldflags = [
+    "-s"
+    "-w"
+    "-X main.version=${version}"
+    "-X main.commit=${version}"
+    "-X main.date=1970-01-01T00:00:00Z"
+    "-X main.builtBy=NixOS"
+  ];
+
+  installPhase = ''
+    mkdir -p $out/bin
+    cp -r "$GOPATH/bin/fail2ban-prometheus-exporter" $out/bin/prometheus-fail2ban-exporter
+  '';
+}