allow overriding the attic endpoint

And also the public key so that pulling from the new endpoint will work.

This allows other people to host their own attic instances and configure
their (CI) environment to override the default endpoint so e.g. they can
take advantage of a binary cache without having write access to the
official one.

I didn't actually test this change but I think it should work.

Also why'd I format the script like that, ew lol

.gitlab-ci.yml

@@ -15,6 +15,10 @@ before_script:
   - if command -v nix > /dev/null; then echo "extra-substituters = https://nix.computer.surgery/conduit" >> /etc/nix/nix.conf; fi
   - if command -v nix > /dev/null; then echo "extra-trusted-public-keys = conduit:ZGAf6P6LhNvnoJJ3Me3PRg7tlLSrPxcQ2RiE5LIppjo=" >> /etc/nix/nix.conf; fi
 
+  # Add alternate binary cache
+  - if command -v nix > /dev/null && [ -n "$ATTIC_ENDPOINT" ]; then echo "extra-substituters = $ATTIC_ENDPOINT" >> /etc/nix/nix.conf; fi
+  - if command -v nix > /dev/null && [ -n "$ATTIC_PUBLIC_KEY" ]; then echo "extra-trusted-public-keys = $ATTIC_PUBLIC_KEY" >> /etc/nix/nix.conf; fi
+
   # Add crane binary cache
   - if command -v nix > /dev/null; then echo "extra-substituters = https://crane.cachix.org" >> /etc/nix/nix.conf; fi
   - if command -v nix > /dev/null; then echo "extra-trusted-public-keys = crane.cachix.org-1:8Scfpmn9w+hGdXH/Q9tTLiYAE/2dnJYRJP7kl80GuRk=" >> /etc/nix/nix.conf; fi

bin/nix-build-and-cache

@@ -9,10 +9,10 @@ INSTALLABLE="$1"
 nix build "$@"
 
 if [ ! -z ${ATTIC_TOKEN+x} ]; then
-
-nix run --inputs-from . attic -- login \
+    nix run --inputs-from . attic -- \
+        login \
         conduit \
-        https://nix.computer.surgery/conduit \
+        "${ATTIC_ENDPOINT:-https://nix.computer.surgery/conduit}" \
         "$ATTIC_TOKEN"
 
     # Push the target installable and its build dependencies