Avoid using lambda in skylet.constant (#3894)

* fix

* add comment

sky/backends/backend_utils.py

@@ -882,6 +882,8 @@ def write_cluster_config(
         f'open(os.path.expanduser("{constants.SKY_REMOTE_RAY_PORT_FILE}"), "w", encoding="utf-8"))\''
     )
 
+    # We disable conda auto-activation if the user has specified a docker image
+    # to use, which is likely to already have a conda environment activated.
     conda_auto_activate = ('true' if to_provision.extract_docker_image() is None
                            else 'false')
 
@@ -919,10 +921,11 @@ def write_cluster_config(
                 'specific_reservations': specific_reservations,
 
                 # Conda setup
-                'conda_installation_commands':
-                    constants.CONDA_INSTALLATION_COMMANDS(conda_auto_activate),
                 # We should not use `.format`, as it contains '{}' as the bash
                 # syntax.
+                'conda_installation_commands':
+                    constants.CONDA_INSTALLATION_COMMANDS.replace(
+                        '{conda_auto_activate}', conda_auto_activate),
                 'ray_skypilot_installation_commands':
                     (constants.RAY_SKYPILOT_INSTALLATION_COMMANDS.replace(
                         '{sky_wheel_hash}',

sky/skylet/constants.py

@@ -126,9 +126,7 @@
 # https://github.com/ray-project/ray/issues/31606
 # We use python 3.10 to be consistent with the python version of the
 # AWS's Deep Learning AMI's default conda environment.
-# Using lambda instead of str.format() since there are multiple {} in the
-# installation commands and we only want to replace some of them.
-CONDA_INSTALLATION_COMMANDS = lambda conda_auto_activate: (
+CONDA_INSTALLATION_COMMANDS = (
     'which conda > /dev/null 2>&1 || '
     '{ curl https://repo.anaconda.com/miniconda/Miniconda3-py310_23.11.0-2-Linux-x86_64.sh -o Miniconda3-Linux-x86_64.sh && '  # pylint: disable=line-too-long
     # We do not use && for installation of conda and the following init commands
@@ -137,7 +135,8 @@
     # true.
     '{ bash Miniconda3-Linux-x86_64.sh -b; '
     'eval "$(~/miniconda3/bin/conda shell.bash hook)" && conda init && '
-    f'conda config --set auto_activate_base {conda_auto_activate} && '
+    # Caller should replace {conda_auto_activate} with either true or false.
+    'conda config --set auto_activate_base {conda_auto_activate} && '
     'conda activate base; }; }; '
     'grep "# >>> conda initialize >>>" ~/.bashrc || '
     '{ conda init && source ~/.bashrc; };'