[Core] Enable use docker image w/ non-default entrypoint as runtime e…

…nv (#3867)

* fix

* fix in cmd runner as well

* add comment in docs

* revert unwanted changes

* add runpod explanation

docs/source/examples/docker-containers.rst

@@ -161,6 +161,15 @@ Any GPUs assigned to the task will be automatically mapped to your Docker contai
 
     2. The container image must grant sudo permissions without requiring password authentication for the user. Having a root user is also acceptable.
 
+.. note::
+
+  Using a container with a customized entrypoint as a runtime environment is
+  supported, with the container's entrypoint being overridden by :code:`/bin/bash`.
+  Specific commands can be executed in the :code:`setup` and :code:`run` sections
+  of the task YAML file. However, this approach is not compatible with RunPod due
+  to limitations in the RunPod API, so ensure that you choose a container with a
+  default entrypoint (i.e. :code:`/bin/bash`).
+
 Private Registries
 ^^^^^^^^^^^^^^^^^^
 

sky/provision/docker_utils.py

@@ -110,8 +110,8 @@ def docker_start_cmds(
         '--cap-add=SYS_ADMIN',
         '--device=/dev/fuse',
         '--security-opt=apparmor:unconfined',
+        '--entrypoint=/bin/bash',
         image,
-        'bash',
     ]
     return ' '.join(docker_run)
 

sky/skylet/providers/command_runner.py

@@ -65,8 +65,8 @@ def docker_start_cmds(
         '--cap-add=SYS_ADMIN',
         '--device=/dev/fuse',
         '--security-opt=apparmor:unconfined',
+        '--entrypoint=/bin/bash',
         image,
-        'bash',
     ]
     return ' '.join(docker_run)