add checks for whether nvidia-docker2 is installed

Fixes #88

src/rocker/core.py

@@ -47,17 +47,31 @@ class DependencyMissing(RuntimeError):
     pass
 
 
+class PrerequisiteCheckError(RuntimeError):
+    pass
+
+
 class RockerExtension(object):
     """The base class for Rocker extension points"""
 
     def precondition_environment(self, cliargs):
         """Modify the local environment such as setup tempfiles"""
         pass
 
-    def validate_environment(self, cliargs):
-        """ Check that the environment is something that can be used.
+    def check_build_prerequisites(self, cliargs):
+        """ Check that the environment is something that can be used for the build.
+        This will check that we're on the right base OS and that the 
+        necessary resources are available, like hardware.
+        Raises PrerequisiteCheckError on failure
+        """
+        pass
+
+    def check_run_prerequisites(self, cliargs):
+        """ Check that the environment is something that can be used for running the container.
         This will check that we're on the right base OS and that the 
-        necessary resources are available, like hardware."""
+        necessary resources are available, like hardware.
+        Raises PrerequisiteCheckError on failure
+        """
         pass
 
     def get_preamble(self, cliargs):
@@ -203,6 +217,14 @@ def __init__(self, active_extensions, cliargs, base_image):
         self.image_id = None
 
     def build(self, **kwargs):
+        # Check prerequisites 
+        for e in self.active_extensions:
+            try:
+                e.check_build_prerequisites(self.cliargs)
+            except PrerequisiteCheckError as ex:
+                print("Failed to validate prerequisites to build for extension [%s] with error: %s\nNot executing run." % (e.get_name(), ex))
+                return 1
+
         with tempfile.TemporaryDirectory() as td:
             df = os.path.join(td, 'Dockerfile')
             print("Writing dockerfile to %s" % df)
@@ -240,10 +262,14 @@ def run(self, command='', **kwargs):
 
         for e in self.active_extensions:
             try:
+                e.check_run_prerequisites(self.cliargs)
                 e.precondition_environment(self.cliargs)
+            except PrerequisiteCheckError as ex:
+                print("Failed to validate prerequisites to run for extension [%s] with error: %s\nNot executing run." % (e.get_name(), ex))
+                return 1
             except subprocess.CalledProcessError as ex:
-                print("Failed to precondition for extension [%s] with error: %s\ndeactivating" % (e.get_name(), ex))
-                # TODO(tfoote) remove the extension from the list
+                print("Failed to precondition environment for extension [%s] with error: %s\nNot executing run." % (e.get_name(), ex))
+                return 1
 
 
         docker_args = ''

src/rocker/nvidia_extension.py

@@ -27,6 +27,7 @@
 from .extensions import name_to_argument
 from .core import get_docker_client
 from .core import RockerExtension
+from .core import PrerequisiteCheckError
 
 def get_docker_version():
     docker_version_raw = get_docker_client().version()['Version']
@@ -125,6 +126,24 @@ def get_docker_args(self, cliargs):
             return "  --gpus all"
         return "  --runtime=nvidia"
 
+    def check_run_prerequisites(self, cliargs):
+        nvidia_flag = ''    
+        if get_docker_version() >= Version("19.03"):
+            nvidia_flag = "  --gpus all"
+        else:
+            nvidia_flag = "  --runtime=nvidia"
+
+        cmd = 'docker run --rm %s nvidia/cuda:11.0-base nvidia-smi' % nvidia_flag
+        try:
+            subprocess.check_call(cmd.split())
+        except:
+            errstr = 'Failed to detect nvidia hardware.'
+            if get_docker_version() >= Version("19.03"):
+                errstr += ' Is nvidia-container-toolkit installed?'
+            else:
+                errstr += 'Is nvidia-docker2 installed?'
+            raise PrerequisiteCheckError(errstr)
+
     @staticmethod
     def register_arguments(parser, defaults={}):
         parser.add_argument(name_to_argument(Nvidia.get_name()),