fix: run nix-gc before pg_upgrade (#1189)

Author: pcnc

ansible/files/admin_api_scripts/pg_upgrade_scripts/initiate.sh

@@ -277,16 +277,23 @@ function initiate_upgrade {
         NIX_FLAKE_VERSION=$(cat "$PG_UPGRADE_BIN_DIR/nix_flake_version")
 
         if [ "$IS_NIX_BASED_SYSTEM" = "false" ]; then
-            echo "1.1. Nix is not installed; installing."
-
-            curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install --no-confirm \
-            --extra-conf "substituters = https://cache.nixos.org https://nix-postgres-artifacts.s3.amazonaws.com" \
-            --extra-conf "trusted-public-keys = nix-postgres-artifacts:dGZlQOvKcNEjvT7QEAJbcV6b6uk7VF/hWMjhYleiaLI=% cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+            if [ ! -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then            
+                if ! command -v nix > /dev/null; then
+                    echo "1.1. Nix is not installed; installing."
+
+                    curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install --no-confirm \
+                    --extra-conf "substituters = https://cache.nixos.org https://nix-postgres-artifacts.s3.amazonaws.com" \
+                    --extra-conf "trusted-public-keys = nix-postgres-artifacts:dGZlQOvKcNEjvT7QEAJbcV6b6uk7VF/hWMjhYleiaLI=% cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+                else 
+                    echo "1.1. Nix is installed; moving on."
+                fi
+            fi
         fi
 
         echo "1.2. Installing flake revision: $NIX_FLAKE_VERSION"
         # shellcheck disable=SC1091
         source /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+        nix-collect-garbage -d > /tmp/pg_upgrade-nix-gc.log 2>&1 || true
         PG_UPGRADE_BIN_DIR=$(nix build "github:supabase/postgres/${NIX_FLAKE_VERSION}#psql_15/bin" --no-link --print-out-paths --extra-experimental-features nix-command --extra-experimental-features flakes)
         PGSHARENEW="$PG_UPGRADE_BIN_DIR/share/postgresql"
     fi