Explicit sandbox config section names, close #165.

law.cfg.example

@@ -48,10 +48,10 @@
 ; information. The law home directory defaults to "$LAW_HOME" or "$HOME/.law".
 
 ; --- Configuration file resolution order ----------------------------------------------------------
-; Law configuration files (like the one you are just reading) are looked up in a certain order:
-; $LAW_CONFIG_FILE, ./law.cfg, "config" in the law home directory, or "etc/law/config". The config
-; parser only reads the first existing file. Please also note the optional synchronization with
-; environment variables described below.
+; Law configuration files are looked up in a certain order: "$LAW_CONFIG_FILE", "./law.cfg",
+; "config" in the law home directory, or "etc/law/config". The config parser only reads the first
+; existing file. Please also note the optional synchronization with environment variables described
+; below.
 
 ; --- Inheritance and extensions -------------------------------------------------------------------
 ; The law configuration can inherit from or can be extended by additional configuration files. See
@@ -1043,7 +1043,7 @@
 ; Note:
 ; Here you can define environment variables via key-value pairs that are accessible in a bash
 ; sandbox. When an option has no value, i.e., when only a key is given, the value of the variable of
-; the current environment is used.
+; the host environment is used.
 ; The environment variables defined in this section are applied to all bash sandboxes. To configure
 ; variables per bash initialization file, create a section "bash_sandbox_env_<init_file>" with the
 ; desired values.
@@ -1087,7 +1087,7 @@
 ; Note:
 ; Here you can define environment variables via key-value pairs that are accessible in a venv
 ; sandbox. When an option has no value, i.e., when only a key is given, the value of the variable of
-; the current environment is used.
+; the host environment is used.
 ; The environment variables defined in this section are applied to all venv sandboxes. To configure
 ; variables per venv directory, create a section "venv_sandbox_env_<venv_dir>" with the desired
 ; values.
@@ -1160,7 +1160,7 @@
 ; Note:
 ; Here you can define environment variables via key-value pairs that are accessible in a docker
 ; sandbox. When an option has no value, i.e., when only a key is given, the value of the variable of
-; the current environment is used.
+; the host environment is used.
 ; The environment variables defined in this section are applied to all docker sandboxes. To
 ; configure variables per image, create a section "docker_sandbox_env_<image_name>" with the desired
 ; values.
@@ -1255,7 +1255,7 @@
 ; Note:
 ; Here you can define environment variables via key-value pairs that are accessible in a singularity
 ; sandbox. When an option has no value, i.e., when only a key is given, the value of the variable of
-; the current environment is used.
+; the host environment is used.
 ; The environment variables defined in this section are applied to all singularity sandboxes. To
 ; configure variables per image, create a section "singularity_sandbox_env_<image_name>" with the
 ; desired values.
@@ -1316,7 +1316,7 @@
 ; Note:
 ; Here you can define environment variables via key-value pairs that are accessible in a cmssw
 ; sandbox. When an option has no value, i.e., when only a key is given, the value of the variable of
-; the current environment is used.
+; the host environment is used.
 ; The environment variables defined in this section are applied to all cmssw sandboxes. To
 ; configure variables per cmssw version, create a section "cmssw_sandbox_env_<cmssw_version>" with
 ; the desired values.

law/config.py

@@ -354,16 +354,16 @@ def include(self, filename, *args, **kwargs):
             skip_luigi_sync=True)
         self.update(p._sections, *args, **kwargs)
 
-    def get_default(self, section, option, default=None, type=None, expand_vars=False,
+    def get_default(self, section, option, default=no_value, type=None, expand_vars=False,
             expand_user=False, split_csv=False, dereference=True, default_when_none=True,
             _skip_refs=None):
-        """ get_default(section, option, default=None, type=None, expand_vars=False, expand_user=False, split_csv=False, dereference=True, default_when_none=True)
+        """ get_default(section, option, default=no_value, type=None, expand_vars=False, expand_user=False, split_csv=False, dereference=True, default_when_none=True)
         Returns the config value defined by *section* and *option*. When either the section or the
-        option does not exist, the *default* value is returned instead. When *type* is set, it must
-        be either `"str"`, `"int"`, `"float"`, or `"boolean"`. When *expand_vars* is *True*,
-        environment variables are expanded. When *expand_user* is *True*, user variables are
-        expanded as well. Sequences of values can be identified, split by comma and returned as a
-        list when *split_csv* is *True*, which will also trigger brace expansion.
+        option do not exist and a *default* value is provided, this value returned instead. When
+        *type* is set, it must be either `"str"`, `"int"`, `"float"`, or `"boolean"`. When
+        *expand_vars* is *True*, environment variables are expanded. When *expand_user* is *True*,
+        user variables are expanded as well. Sequences of values can be identified, split by comma
+        and returned as a list when *split_csv* is *True*, which will also trigger brace expansion.
 
         Also, options retrieved by this method are allowed to refer to values of other options
         within the config, even to those in other sections. The syntax for config references is
@@ -382,11 +382,12 @@ def get_default(self, section, option, default=None, type=None, expand_vars=Fals
         This behavior is the default and, if desired, can be disabled by setting *dereference* to
         *False*. When the reference is not resolvable, the default value is returned.
 
-        When *default_when_none* is *True* and the option was found but its value is *None* or
-        ``"None"`` (case-insensitive), the *default* is returned.
+        When *default_when_none* is *True*, a *default* value is provided, and the option was found
+        but its value is *None* or ``"None"`` (case-insensitive), the *default* is returned.
         """  # noqa
         # return the default when either the section or the option does not exist
-        if not self.has_section(section) or not self.has_option(section, option):
+        default_set = default != no_value
+        if (not self.has_section(section) or not self.has_option(section, option)) and default_set:
             return default
 
         # get the value
@@ -418,10 +419,10 @@ def get_default(self, section, option, default=None, type=None, expand_vars=Fals
                         default_when_none=default_when_none, _skip_refs=_skip_refs)
 
         # interpret None and "None" as missing?
-        if default_when_none:
+        if default_when_none and default_set:
             if value is None:
                 return default
-            elif isinstance(value, six.string_types) and value.lower() == "none":
+            if isinstance(value, six.string_types) and value.lower() == "none":
                 return default
 
         # helper for optional type conversion

law/contrib/docker/sandbox.py

@@ -27,6 +27,8 @@ class DockerSandbox(Sandbox):
 
     sandbox_type = "docker"
 
+    config_section_prefix = sandbox_type
+
     @property
     def image(self):
         return self.name

law/contrib/singularity/sandbox.py

@@ -24,6 +24,8 @@ class SingularitySandbox(Sandbox):
 
     sandbox_type = "singularity"
 
+    config_section_prefix = sandbox_type
+
     @property
     def image(self):
         return self.name

law/logger.py

@@ -105,7 +105,7 @@ def setup_logger(logger, level=None, add_console_handler=None, clear=False, forc
     # sanitize the level
     if level is None:
         from law.config import Config
-        level = Config.instance().get_expanded("logging", name)
+        level = Config.instance().get_expanded("logging", name, None)
     if isinstance(level, six.string_types):
         level = getattr(logging, level.upper(), None)
     if level is None:

law/sandbox/base.py

@@ -88,6 +88,17 @@ def __repr__(self):
 
 
 class Sandbox(six.with_metaclass(ABCMeta, object)):
+    """
+    Sandbox definition.
+
+    The config section used by instances if this or inheriting classes constructed using
+    :py:attr:`config_section_prefix` followed by ``"_sandbox"`` and optional postifxes. The minimal
+    set of options in the main section are:
+
+        - ``"stagein_dir_name"`` (usually ``"stagein"``)
+        - ``"stageout_dir_name"`` (usually ``"stageout"``)
+        - ``"law_executable"`` (usually ``"law"``)
+    """
 
     delimiter = "::"
 
@@ -178,6 +189,10 @@ def scheduler_on_host(self):
     def force_local_scheduler(self):
         return False
 
+    @abstractproperty
+    def config_section_prefix(self):
+        return
+
     @abstractproperty
     def env_cache_key(self):
         return
@@ -218,7 +233,7 @@ def get_custom_config_section_postfix(self):
         return self.name
 
     def get_config_section(self, postfix=None):
-        section = self.sandbox_type + "_sandbox"
+        section = self.config_section_prefix + "_sandbox"
         if postfix:
             section += "_" + postfix
 

law/sandbox/bash.py

@@ -21,6 +21,8 @@ class BashSandbox(Sandbox):
 
     sandbox_type = "bash"
 
+    config_section_prefix = sandbox_type
+
     @property
     def script(self):
         return os.path.expandvars(os.path.expanduser(self.name))

law/sandbox/venv.py

@@ -20,6 +20,8 @@ class VenvSandbox(Sandbox):
 
     sandbox_type = "venv"
 
+    config_section_prefix = sandbox_type
+
     @property
     def venv_dir(self):
         return os.path.expandvars(os.path.expanduser(self.name))