Add env for nix-shell which pins nixpkgs and automatically creates secrets

secrets/generate_secrets.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+SECRETSFILE=secrets/secrets.nix
+
+if [ -e "$SECRETSFILE" ]; then
+    echo $SECRETSFILE already exists. No new secrets were generated.
+    exit 1
+fi
+
+echo Installing apg through nix-env
+echo Write secrets to $SECRETSFILE
+{
+    echo \{
+    echo "  bitcoinrpcpassword = \"$(apg -m 20 -x 20 -M Ncl -n 1)\";"
+    echo "  lightning-charge-api-token = \"$(apg -m 20 -x 20 -M Ncl -n 1)\";"
+    echo "  liquidrpcpassword = \"$(apg -m 20 -x 20 -M Ncl -n 1)\";"
+    echo "  spark-wallet-password = \"$(apg -m 20 -x 20 -M Ncl -n 1)\";"
+    echo \}
+} >> $SECRETSFILE
+echo Done