topology: include the peerSnapshotFile for all networks

Author: johnalotoski

cardano-lib/default.nix

@@ -71,11 +71,20 @@ let
       bootstrapPeers = map (e: {address = e.addr; inherit (e) port;}) env.edgeNodes;
       useLedgerAfterSlot = env.useLedgerAfterSlot;
 
-      # Genesis mode is now default for preview and preprod as of node 10.5
-      peerSnapshotFile =
-        if elem env.name ["preview" "preprod"]
-        then "peer-snapshot.json"
-        else null;
+      # Genesis mode is now default for preview and preprod as of node 10.5.0.
+      #
+      # As of node 10.5.0, the peer snapshot file can be added to the
+      # topology file with a relative path to itself making the packaging
+      # cleaner.
+      #
+      # As of node 10.6.0, the peer snapshot file can be added to the
+      # topology file and not be fatal if missing while in PraosMode.
+      #
+      # Given that the peer snapshot file will be required as soon as genesis
+      # mode is default, and migration to genesis mode for all networks is
+      # coming soon, the snapshot will be declared in all network topologies
+      # which also makes genesis testing a bit easier.
+      peerSnapshotFile = "peer-snapshot.json";
     };
   in
     if (env.nodeConfig.EnableP2P or false)