Make local-evaluation overridable at runtime

Adds an environment variable `LP_LOCAL_EVALUATION` which overrides
`lollypops.deployment.local-evaluation` at runtime.

Use case: Sometimes I'm deploying from my main workstation which is
more powerful than the servers, so building locally makes sense. Other
times I'm deploying from my crappy ARM laptop which is barely capable of
building itself. I'd like to switch from one to the other without having
to modify the flake of my system.

README.md

@@ -213,9 +213,9 @@ lollypops.deployment = {
 };
 ```
 
-Setting `lollypops.deployment.local-evaluation` to true, will result in
-evaluation being done on the local side. This requires `nixos-rebuild` in your
-`$PATH`
+Setting `lollypops.deployment.local-evaluation` or the environment variable
+`LP_LOCAL_EVALUATION` to true, will result in evaluation being done on the
+local side. This requires `nixos-rebuild` in your `$PATH`.
 
 **Note:** Rsync is required on the remote for remote evaluation to work. While
 the lollypops module will add the package to `environment.systemPackages` it may

flake.nix

@@ -104,6 +104,7 @@
                         REBUILD_ACTION = ''{{default "switch" .REBUILD_ACTION}}'';
                         REMOTE_CONFIG_DIR = deployment.config-dir;
                         LOCAL_FLAKE_SOURCE = configFlake;
+                        LOCAL_EVALUATION = ''{{default "${pkgs.lib.optionalString deployment.local-evaluation "true"}" .LP_LOCAL_EVALUATION}}'';
                         HOSTNAME = hostName;
                       };
 
@@ -179,17 +180,19 @@
                             desc = "Rebuild configuration of: ${hostName}";
                             deps = [ "check-vars" ];
                             cmds = [
-                              (if hostConfig.config.lollypops.deployment.local-evaluation then
-                                ''
+                              ''
+                                if [ "{{.LOCAL_EVALUATION}}" = "true" ]
+                                then
                                   NIX_SSHOPTS="{{.REMOTE_SSH_OPTS}}" nixos-rebuild {{.REBUILD_ACTION}} \
                                     --flake '{{.LOCAL_FLAKE_SOURCE}}#{{.HOSTNAME}}' \
                                     --target-host {{.REMOTE_USER}}@{{.REMOTE_HOST}} \
                                     ${optionalString useSudo "--use-remote-sudo"}
-                                '' else ''
-                                {{.REMOTE_COMMAND}} {{.REMOTE_SSH_OPTS}} {{.REMOTE_USER}}@{{.REMOTE_HOST}} \
-                                "${optionalString useSudo "{{.REMOTE_SUDO_COMMAND}} {{.REMOTE_SUDO_OPTS}}"} nixos-rebuild {{.REBUILD_ACTION}} \
-                                --flake '{{.REMOTE_CONFIG_DIR}}#{{.HOSTNAME}}'"
-                              '')
+                                else
+                                  {{.REMOTE_COMMAND}} {{.REMOTE_SSH_OPTS}} {{.REMOTE_USER}}@{{.REMOTE_HOST}} \
+                                    "${optionalString useSudo "{{.REMOTE_SUDO_COMMAND}} {{.REMOTE_SUDO_OPTS}}"} nixos-rebuild {{.REBUILD_ACTION}} \
+                                    --flake '{{.REMOTE_CONFIG_DIR}}#{{.HOSTNAME}}'"
+                                fi
+                              ''
                             ];
                           };