config: simplify configuration API to just get and set

- replace `spack.config.get_configuration()` with `spack.config.config()`

- replace `get_config`/`update_config` with `get`, `set`

- add a path syntax that can be used to refer to specific config options
  without firt getting the entire configuration dict

- update usages of `get_config` and `update_config` to use `get` and `set`

31 files changed, 207 insertions, 173 deletions

diff --git a/lib/spack/spack/__init__.py b/lib/spack/spack/__init__.py
index 863e8f8016..af306461bf 100644
--- a/lib/spack/spack/__init__.py
+++ b/lib/spack/spack/__init__.py
@@ -41,35 +41,33 @@ import spack.config
 from spack.util.path import canonicalize_path
 
 
-_config = spack.config.get_config('config')
-
 # TODO: get this out of __init__.py
 binary_cache_retrieved_specs = set()
 
 
 #: Directories where to search for templates
-template_dirs = spack.config.get_config('config')['template_dirs']
+template_dirs = spack.config.get('config:template_dirs')
 template_dirs = [canonicalize_path(x) for x in template_dirs]
 
 
 #: If this is enabled, tools that use SSL should not verify
 #: certifiates. e.g., curl should use the -k option.
-insecure = not _config.get('verify_ssl', True)
+insecure = not spack.config.get('config:verify_ssl', True)
 
 
 #: Whether spack should allow installation of unsafe versions of software.
 #: "Unsafe" versions are ones it doesn't have a checksum for.
-do_checksum = _config.get('checksum', True)
+do_checksum = spack.config.get('config:checksum', True)
 
 
 # If this is True, spack will not clean the environment to remove
 # potentially harmful variables before builds.
-dirty = _config.get('dirty', False)
+dirty = spack.config.get('config:dirty', False)
 
 
 #: The number of jobs to use when building in parallel.
 #: By default, use all cores on the machine.
-build_jobs = _config.get('build_jobs', multiprocessing.cpu_count())
+build_jobs = spack.config.get('config:build_jobs', multiprocessing.cpu_count())
 
 
 #-----------------------------------------------------------------------------
diff --git a/lib/spack/spack/binary_distribution.py b/lib/spack/spack/binary_distribution.py
index e87a4c7391..fe0924fddb 100644
--- a/lib/spack/spack/binary_distribution.py
+++ b/lib/spack/spack/binary_distribution.py
@@ -364,7 +364,7 @@ def download_tarball(spec):
     Download binary tarball for given package into stage area
     Return True if successful
     """
-    mirrors = spack.config.get_config('mirrors')
+    mirrors = spack.config.get('mirrors')
     if len(mirrors) == 0:
         tty.die("Please add a spack mirror to allow " +
                 "download of pre-compiled packages.")
@@ -538,7 +538,7 @@ def get_specs(force=False):
         previously_retrieved = spack.binary_cache_retrieved_specs
         return previously_retrieved
 
-    mirrors = spack.config.get_config('mirrors')
+    mirrors = spack.config.get('mirrors')
     if len(mirrors) == 0:
         tty.warn("No Spack mirrors are currently configured")
         return {}
@@ -588,7 +588,7 @@ def get_keys(install=False, trust=False, force=False):
     """
     Get pgp public keys available on mirror
     """
-    mirrors = spack.config.get_config('mirrors')
+    mirrors = spack.config.get('mirrors')
     if len(mirrors) == 0:
         tty.die("Please add a spack mirror to allow " +
                 "download of build caches.")
diff --git a/lib/spack/spack/caches.py b/lib/spack/spack/caches.py
index ff2bb7a7c6..196cbb8bad 100644
--- a/lib/spack/spack/caches.py
+++ b/lib/spack/spack/caches.py
@@ -44,8 +44,7 @@ def misc_cache():
     global _misc_cache
 
     if _misc_cache is None:
-        config = spack.config.get_config('config')
-        path = config.get('misc_cache')
+        path = spack.config.get('config:misc_cache')
         if not path:
             path = os.path.join(spack.paths.user_config_path, 'cache')
         path = canonicalize_path(path)
@@ -63,8 +62,7 @@ def fetch_cache():
     global _fetch_cache
 
     if _fetch_cache is None:
-        config = spack.config.get_config('config')
-        path = config.get('source_cache')
+        path = spack.config.get('config:source_cache')
         if not path:
             path = os.path.join(spack.paths.var_path, "cache")
         path = canonicalize_path(path)
diff --git a/lib/spack/spack/cmd/__init__.py b/lib/spack/spack/cmd/__init__.py
index 6c03650fb9..0f645af5f0 100644
--- a/lib/spack/spack/cmd/__init__.py
+++ b/lib/spack/spack/cmd/__init__.py
@@ -49,8 +49,7 @@ def default_modify_scope():
     Commands that modify configuration by default modify the *highest*
     priority scope.
     """
-    config = spack.config.get_configuration()
-    return config.highest_precedence_scope().name
+    return spack.config.config().highest_precedence_scope().name
 
 
 def default_list_scope():
diff --git a/lib/spack/spack/cmd/compiler.py b/lib/spack/spack/cmd/compiler.py
index fc85f28a90..e16cb90a6c 100644
--- a/lib/spack/spack/cmd/compiler.py
+++ b/lib/spack/spack/cmd/compiler.py
@@ -46,7 +46,8 @@ def setup_parser(subparser):
     sp = subparser.add_subparsers(
         metavar='SUBCOMMAND', dest='compiler_command')
 
-    scopes = spack.config.get_configuration().scopes
+    scopes = spack.config.scopes()
+    scopes_metavar = spack.config.scopes_metavar
 
     # Find
     find_parser = sp.add_parser(
@@ -54,7 +55,7 @@ def setup_parser(subparser):
         help='search the system for compilers to add to Spack configuration')
     find_parser.add_argument('add_paths', nargs=argparse.REMAINDER)
     find_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
@@ -66,14 +67,14 @@ def setup_parser(subparser):
         help='remove ALL compilers that match spec')
     remove_parser.add_argument('compiler_spec')
     remove_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
     # List
     list_parser = sp.add_parser('list', help='list available compilers')
     list_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_list_scope(),
         help="configuration scope to read from")
 
@@ -81,7 +82,7 @@ def setup_parser(subparser):
     info_parser = sp.add_parser('info', help='show compiler paths')
     info_parser.add_argument('compiler_spec')
     info_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_list_scope(),
         help="configuration scope to read from")
 
@@ -114,7 +115,7 @@ def compiler_find(args):
         n = len(new_compilers)
         s = 's' if n > 1 else ''
 
-        config = spack.config.get_configuration()
+        config = spack.config.config()
         filename = config.get_config_filename(args.scope, 'compilers')
         tty.msg("Added %d new compiler%s to %s" % (n, s, filename))
         colify(reversed(sorted(c.spec for c in new_compilers)), indent=4)
diff --git a/lib/spack/spack/cmd/compilers.py b/lib/spack/spack/cmd/compilers.py
index dc3e81920e..77e20119a2 100644
--- a/lib/spack/spack/cmd/compilers.py
+++ b/lib/spack/spack/cmd/compilers.py
@@ -31,9 +31,11 @@ level = "short"
 
 
 def setup_parser(subparser):
-    scopes = spack.config.get_configuration().scopes
+    scopes = spack.config.scopes()
+    scopes_metavar = spack.config.scopes_metavar
+
     subparser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         help="configuration scope to read/modify")
 
 
diff --git a/lib/spack/spack/cmd/config.py b/lib/spack/spack/cmd/config.py
index 1c5b96059c..984126f215 100644
--- a/lib/spack/spack/cmd/config.py
+++ b/lib/spack/spack/cmd/config.py
@@ -30,10 +30,12 @@ level = "long"
 
 
 def setup_parser(subparser):
+    scopes = spack.config.scopes()
+    scopes_metavar = spack.config.scopes_metavar
+
     # User can only choose one
     subparser.add_argument(
-        '--scope', choices=spack.config.get_configuration().scopes,
-        metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         help="configuration scope to read/modify")
 
     sp = subparser.add_subparsers(metavar='SUBCOMMAND', dest='config_command')
@@ -54,8 +56,7 @@ def setup_parser(subparser):
 
 
 def config_get(args):
-    config = spack.config.get_configuration()
-    config.print_section(args.section)
+    spack.config.config().print_section(args.section)
 
 
 def config_edit(args):
@@ -67,7 +68,7 @@ def config_edit(args):
     if not args.section:
         args.section = None
 
-    config = spack.config.get_configuration()
+    config = spack.config.config()
     config_file = config.get_config_filename(args.scope, args.section)
     spack.editor(config_file)
 
diff --git a/lib/spack/spack/cmd/mirror.py b/lib/spack/spack/cmd/mirror.py
index b91531cf54..ef0997b534 100644
--- a/lib/spack/spack/cmd/mirror.py
+++ b/lib/spack/spack/cmd/mirror.py
@@ -67,7 +67,9 @@ def setup_parser(subparser):
         const=1, default=0,
         help="only fetch one 'preferred' version per spec, not all known")
 
-    scopes = spack.config.get_configuration().scopes
+    # used to construct scope arguments below
+    scopes = spack.config.scopes()
+    scopes_metavar = spack.config.scopes_metavar
 
     # Add
     add_parser = sp.add_parser('add', help=mirror_add.__doc__)
@@ -75,7 +77,7 @@ def setup_parser(subparser):
     add_parser.add_argument(
         'url', help="url of mirror directory from 'spack mirror create'")
     add_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
@@ -84,14 +86,14 @@ def setup_parser(subparser):
                                   help=mirror_remove.__doc__)
     remove_parser.add_argument('name')
     remove_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
     # List
     list_parser = sp.add_parser('list', help=mirror_list.__doc__)
     list_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_list_scope(),
         help="configuration scope to read from")
 
@@ -102,7 +104,7 @@ def mirror_add(args):
     if url.startswith('/'):
         url = 'file://' + url
 
-    mirrors = spack.config.get_config('mirrors', scope=args.scope)
+    mirrors = spack.config.get('mirrors', scope=args.scope)
     if not mirrors:
         mirrors = syaml_dict()
 
@@ -116,14 +118,14 @@ def mirror_add(args):
     items = [(n, u) for n, u in mirrors.items()]
     items.insert(0, (args.name, url))
     mirrors = syaml_dict(items)
-    spack.config.update_config('mirrors', mirrors, scope=args.scope)
+    spack.config.set('mirrors', mirrors, scope=args.scope)
 
 
 def mirror_remove(args):
     """Remove a mirror by name."""
     name = args.name
 
-    mirrors = spack.config.get_config('mirrors', scope=args.scope)
+    mirrors = spack.config.get('mirrors', scope=args.scope)
     if not mirrors:
         mirrors = syaml_dict()
 
@@ -131,13 +133,13 @@ def mirror_remove(args):
         tty.die("No mirror with name %s" % name)
 
     old_value = mirrors.pop(name)
-    spack.config.update_config('mirrors', mirrors, scope=args.scope)
+    spack.config.set('mirrors', mirrors, scope=args.scope)
     tty.msg("Removed mirror %s with url %s" % (name, old_value))
 
 
 def mirror_list(args):
     """Print out available mirrors to the console."""
-    mirrors = spack.config.get_config('mirrors', scope=args.scope)
+    mirrors = spack.config.get('mirrors', scope=args.scope)
     if not mirrors:
         tty.msg("No mirrors configured.")
         return
diff --git a/lib/spack/spack/cmd/repo.py b/lib/spack/spack/cmd/repo.py
index 81484f4e85..ca720d7308 100644
--- a/lib/spack/spack/cmd/repo.py
+++ b/lib/spack/spack/cmd/repo.py
@@ -39,7 +39,8 @@ level = "long"
 
 def setup_parser(subparser):
     sp = subparser.add_subparsers(metavar='SUBCOMMAND', dest='repo_command')
-    scopes = spack.config.get_configuration().scopes
+    scopes = spack.config.scopes()
+    scopes_metavar = spack.config.scopes_metavar
 
     # Create
     create_parser = sp.add_parser('create', help=repo_create.__doc__)
@@ -52,7 +53,7 @@ def setup_parser(subparser):
     # List
     list_parser = sp.add_parser('list', help=repo_list.__doc__)
     list_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_list_scope(),
         help="configuration scope to read from")
 
@@ -61,7 +62,7 @@ def setup_parser(subparser):
     add_parser.add_argument(
         'path', help="path to a Spack package repository directory")
     add_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
@@ -72,7 +73,7 @@ def setup_parser(subparser):
         'path_or_namespace',
         help="path or namespace of a Spack package repository")
     remove_parser.add_argument(
-        '--scope', choices=scopes, metavar=spack.config.scopes_metavar,
+        '--scope', choices=scopes, metavar=scopes_metavar,
         default=spack.cmd.default_modify_scope(),
         help="configuration scope to modify")
 
@@ -104,7 +105,7 @@ def repo_add(args):
     repo = Repo(canon_path)
 
     # If that succeeds, finally add it to the configuration.
-    repos = spack.config.get_config('repos', args.scope)
+    repos = spack.config.get('repos', scope=args.scope)
     if not repos:
         repos = []
 
@@ -112,13 +113,13 @@ def repo_add(args):
         tty.die("Repository is already registered with Spack: %s" % path)
 
     repos.insert(0, canon_path)
-    spack.config.update_config('repos', repos, args.scope)
+    spack.config.set('repos', repos, args.scope)
     tty.msg("Added repo with namespace '%s'." % repo.namespace)
 
 
 def repo_remove(args):
     """Remove a repository from Spack's configuration."""
-    repos = spack.config.get_config('repos', args.scope)
+    repos = spack.config.get('repos', scope=args.scope)
     path_or_namespace = args.path_or_namespace
 
     # If the argument is a path, remove that repository from config.
@@ -127,7 +128,7 @@ def repo_remove(args):
         repo_canon_path = canonicalize_path(repo_path)
         if canon_path == repo_canon_path:
             repos.remove(repo_path)
-            spack.config.update_config('repos', repos, args.scope)
+            spack.config.set('repos', repos, args.scope)
             tty.msg("Removed repository %s" % repo_path)
             return
 
@@ -137,7 +138,7 @@ def repo_remove(args):
             repo = Repo(path)
             if repo.namespace == path_or_namespace:
                 repos.remove(path)
-                spack.config.update_config('repos', repos, args.scope)
+                spack.config.set('repos', repos, args.scope)
                 tty.msg("Removed repository %s with namespace '%s'."
                         % (repo.root, repo.namespace))
                 return
@@ -150,7 +151,7 @@ def repo_remove(args):
 
 def repo_list(args):
     """Show registered repositories and their namespaces."""
-    roots = spack.config.get_config('repos', args.scope)
+    roots = spack.config.get('repos', scope=args.scope)
     repos = []
     for r in roots:
         try:
diff --git a/lib/spack/spack/compilers/__init__.py b/lib/spack/spack/compilers/__init__.py
index eb637259b5..c45e838374 100644
--- a/lib/spack/spack/compilers/__init__.py
+++ b/lib/spack/spack/compilers/__init__.py
@@ -88,9 +88,9 @@ def get_compiler_config(scope=None, init_config=True):
         compilers_dict = []
         for compiler in compilers:
             compilers_dict.append(_to_dict(compiler))
-        spack.config.update_config('compilers', compilers_dict, scope=scope)
+        spack.config.set('compilers', compilers_dict, scope=scope)
 
-    config = spack.config.get_config('compilers', scope=scope)
+    config = spack.config.get('compilers', scope=scope)
     # Update the configuration if there are currently no compilers
     # configured.  Avoid updating automatically if there ARE site
     # compilers configured but no user ones.
@@ -98,15 +98,15 @@ def get_compiler_config(scope=None, init_config=True):
         if scope is None:
             # We know no compilers were configured in any scope.
             init_compiler_config()
-            config = spack.config.get_config('compilers', scope=scope)
+            config = spack.config.get('compilers', scope=scope)
         elif scope == 'user':
             # Check the site config and update the user config if
             # nothing is configured at the site level.
-            site_config = spack.config.get_config('compilers', scope='site')
-            sys_config = spack.config.get_config('compilers', scope='system')
+            site_config = spack.config.get('compilers', scope='site')
+            sys_config = spack.config.get('compilers', scope='system')
             if not site_config and not sys_config:
                 init_compiler_config()
-                config = spack.config.get_config('compilers', scope=scope)
+                config = spack.config.get('compilers', scope=scope)
         return config
     elif config:
         return config
@@ -116,10 +116,10 @@ def get_compiler_config(scope=None, init_config=True):
 
 def compiler_config_files():
     config_files = list()
-    config = spack.config.get_configuration()
+    config = spack.config.config()
     for scope in config.file_scopes:
         name = scope.name
-        compiler_config = config.get_config('compilers', scope=name)
+        compiler_config = config.get('compilers', scope=name)
         if compiler_config:
             config_files.append(config.get_config_filename(name, 'compilers'))
     return config_files
@@ -137,7 +137,7 @@ def add_compilers_to_config(compilers, scope=None, init_config=True):
         compiler_config.append(_to_dict(compiler))
     global _cache_config_file
     _cache_config_file = compiler_config
-    spack.config.update_config('compilers', compiler_config, scope)
+    spack.config.set('compilers', compiler_config, scope=scope)
 
 
 @_auto_compiler_spec
@@ -162,7 +162,7 @@ def remove_compiler_from_config(compiler_spec, scope=None):
     _cache_config_file = filtered_compiler_config
     if len(filtered_compiler_config) == config_length:  # No items removed
         CompilerSpecInsufficientlySpecificError(compiler_spec)
-    spack.config.update_config('compilers', filtered_compiler_config, scope)
+    spack.config.set('compilers', filtered_compiler_config, scope=scope)
 
 
 def all_compilers_config(scope=None, init_config=True):
@@ -339,7 +339,7 @@ def compiler_for_spec(compiler_spec, arch_spec):
 
 @_auto_compiler_spec
 def get_compiler_duplicates(compiler_spec, arch_spec):
-    config = spack.config.get_configuration()
+    config = spack.config.config()
 
     scope_to_compilers = {}
     for scope in config.scopes:
diff --git a/lib/spack/spack/config.py b/lib/spack/spack/config.py
index d622f0416d..b481c48692 100644
--- a/lib/spack/spack/config.py
+++ b/lib/spack/spack/config.py
@@ -109,10 +109,6 @@ configuration_paths = (
 scopes_metavar = '{defaults,system,site,user}[/PLATFORM]'
 
 
-#: config scopes only used by Spack internally
-internal_scopes = ['commands']
-
-
 def _extend_with_default(validator_class):
     """Add support for the 'default' attr for properties and patternProperties.
 
@@ -379,6 +375,54 @@ class Configuration(object):
         # take the top key off before returning.
         return merged_section[section]
 
+    def get(self, path, default=None, scope=None):
+        """Get a config section or a single value from one.
+
+        Accepts a path syntax that allows us to grab nested config map
+        entries.  Getting the 'config' section would look like::
+
+            spack.config.get('config')
+
+        and the ``dirty`` section in the ``config`` scope would be::
+
+            spack.config.get('config:dirty')
+
+        We use ``:`` as the separator, like YAML objects.
+    """
+        # TODO: Currently only handles maps. Think about lists if neded.
+        section, _, rest = path.partition(':')
+
+        value = self.get_config(section, scope=scope)
+        if not rest:
+            return value
+
+        parts = rest.split(':')
+        while parts:
+            key = parts.pop(0)
+            value = value.get(key, default)
+        return value
+
+    def set(self, path, value, scope=None):
+        """Convenience function for setting single values in config files.
+
+        Accepts the path syntax described in ``get()``.
+        """
+        section, _, rest = path.partition(':')
+
+        if not rest:
+            self.update_config(section, value, scope=scope)
+        else:
+            section_data = self.get_config(section, scope=scope)
+
+            parts = rest.split(':')
+            data = section_data
+            while len(parts) > 1:
+                key = parts.pop(0)
+                data = data[key]
+            data[parts[0]] = value
+
+            self.update_config(section, section_data, scope=scope)
+
     def __iter__(self):
         """Iterate over scopes in this configuration."""
         for scope in self.scopes.values():
@@ -394,15 +438,15 @@ class Configuration(object):
             raise ConfigError("Error reading configuration: %s" % section)
 
 
-def get_configuration():
-    """This constructs Spack's standard configuration scopes
+def config():
+    """Singleton Configuration instance.
 
-    This is a singleton; it constructs one instance associated with this
-    module and returns it. It is bundled inside a function so that
-    configuratoin can be initialized lazily.
+    This constructs one instance associated with this module and returns
+    it. It is bundled inside a function so that configuratoin can be
+    initialized lazily.
 
     Return:
-        Configuration: object for accessing spack configuration
+        (Configuration): object for accessing spack configuration
 
     """
     global _configuration
@@ -423,7 +467,7 @@ def get_configuration():
 
         # we make a special scope for spack commands so that they can
         # override configuration options.
-        _configuration.push_scope(InternalConfigScope('commands'))
+        _configuration.push_scope(InternalConfigScope('command_line'))
 
     return _configuration
 
@@ -433,17 +477,22 @@ def get_configuration():
 _configuration = None
 
 
-#: TODO: consider getting rid of these top-level wrapper functions.
-def get_config(section, scope=None):
-    """Module-level interface for ``Configuration.get_config()``."""
-    config = get_configuration()
-    return config.get_config(section, scope)
+def get(path, default=None, scope=None):
+    """Module-level wrapper for ``Configuration.get()``."""
+    return config().get(path, default, scope)
+
+
+def set(path, value, scope=None):
+    """Convenience function for getting single values in config files.
+
+    Accepts the path syntax described in ``get()``.
+    """
+    return config().set(path, value, scope)
 
 
-def update_config(section, update_data, scope=None):
-    """Module-level interface for ``Configuration.update_config()``."""
-    config = get_configuration()
-    return config.update_config(section, update_data, scope)
+def scopes():
+    """Convenience function to get list of configuration scopes."""
+    return config().scopes
 
 
 def _validate_section_name(section):
diff --git a/lib/spack/spack/hooks/module_file_generation.py b/lib/spack/spack/hooks/module_file_generation.py
index 0136150034..ce7df4c717 100644
--- a/lib/spack/spack/hooks/module_file_generation.py
+++ b/lib/spack/spack/hooks/module_file_generation.py
@@ -27,7 +27,7 @@ import spack.modules.common
 import llnl.util.tty as tty
 
 try:
-    enabled = spack.modules.common.configuration['enable']
+    enabled = spack.config.get('modules:enable')
 except KeyError:
     tty.debug('NO MODULE WRITTEN: list of enabled module files is empty')
     enabled = []
diff --git a/lib/spack/spack/hooks/yaml_version_check.py b/lib/spack/spack/hooks/yaml_version_check.py
index a2bccf1fb1..af9d2443ca 100644
--- a/lib/spack/spack/hooks/yaml_version_check.py
+++ b/lib/spack/spack/hooks/yaml_version_check.py
@@ -36,7 +36,7 @@ def pre_run():
 
 
 def check_compiler_yaml_version():
-    config = spack.config.get_configuration()
+    config = spack.config.config()
 
     for scope in config.file_scopes:
         file_name = os.path.join(scope.path, 'compilers.yaml')
diff --git a/lib/spack/spack/modules/common.py b/lib/spack/spack/modules/common.py
index dfb5e6ab24..bf0188a716 100644
--- a/lib/spack/spack/modules/common.py
+++ b/lib/spack/spack/modules/common.py
@@ -65,14 +65,14 @@ import spack.util.path
 import spack.util.environment
 import spack.error
 
-#: Root folders where the various module files should be written
-roots = spack.config.get_config('config').get('module_roots', {})
+#: config section for this file
+configuration = spack.config.get('modules')
 
-#: Merged modules.yaml as a dictionary
-configuration = spack.config.get_config('modules')
+#: Root folders where the various module files should be written
+roots = spack.config.get('config:module_roots', {})
 
 #: Inspections that needs to be done on spec prefixes
-prefix_inspections = configuration.get('prefix_inspections', {})
+prefix_inspections = spack.config.get('modules:prefix_inspections', {})
 
 #: Valid tokens for naming scheme and env variable names
 _valid_tokens = (
diff --git a/lib/spack/spack/modules/dotkit.py b/lib/spack/spack/modules/dotkit.py
index 3d30f113d5..42cfe24f9f 100644
--- a/lib/spack/spack/modules/dotkit.py
+++ b/lib/spack/spack/modules/dotkit.py
@@ -25,11 +25,12 @@
 """This module implements the classes necessary to generate dotkit modules."""
 import os.path
 
+import spack.config
 from .common import BaseConfiguration, BaseFileLayout
-from .common import BaseContext, BaseModuleFileWriter, configuration
+from .common import BaseContext, BaseModuleFileWriter
 
 #: Dotkit specific part of the configuration
-configuration = configuration.get('dotkit', {})
+configuration = spack.config.get('modules:dotkit', {})
 
 #: Caches the configuration {spec_hash: configuration}
 configuration_registry = {}
diff --git a/lib/spack/spack/modules/lmod.py b/lib/spack/spack/modules/lmod.py
index 5c5c454de5..aa41b27daa 100644
--- a/lib/spack/spack/modules/lmod.py
+++ b/lib/spack/spack/modules/lmod.py
@@ -22,21 +22,23 @@
 # License along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
-
 import os.path
+
 import llnl.util.lang as lang
+import itertools
+import collections
+
+import spack.config
 import spack.compilers
 import spack.spec
 import spack.error
-import itertools
-import collections
 import spack.tengine as tengine
 
 from .common import BaseConfiguration, BaseFileLayout
-from .common import BaseContext, BaseModuleFileWriter, configuration
+from .common import BaseContext, BaseModuleFileWriter
 
-#: LMOD specific part of the configuration
-configuration = configuration.get('lmod', {})
+#: TCL specific part of the configuration
+configuration = spack.config.get('modules:lmod', {})
 
 #: Caches the configuration {spec_hash: configuration}
 configuration_registry = {}
diff --git a/lib/spack/spack/modules/tcl.py b/lib/spack/spack/modules/tcl.py
index 815509962b..05cb393b65 100644
--- a/lib/spack/spack/modules/tcl.py
+++ b/lib/spack/spack/modules/tcl.py
@@ -27,15 +27,16 @@ non-hierarchical modules.
 """
 import os.path
 import string
-import spack.tengine as tengine
 
 import llnl.util.tty as tty
 
+import spack.config
+import spack.tengine as tengine
 from .common import BaseConfiguration, BaseFileLayout
-from .common import BaseContext, BaseModuleFileWriter, configuration
+from .common import BaseContext, BaseModuleFileWriter
 
 #: TCL specific part of the configuration
-configuration = configuration.get('tcl', {})
+configuration = spack.config.get('modules:tcl', {})
 
 #: Caches the configuration {spec_hash: configuration}
 configuration_registry = {}
diff --git a/lib/spack/spack/package_prefs.py b/lib/spack/spack/package_prefs.py
index 10c6ede916..60b501acee 100644
--- a/lib/spack/spack/package_prefs.py
+++ b/lib/spack/spack/package_prefs.py
@@ -44,7 +44,7 @@ def _spec_type(component):
 
 def get_packages_config():
     """Wrapper around get_packages_config() to validate semantics."""
-    config = spack.config.get_config('packages')
+    config = spack.config.get('packages')
 
     # Get a list of virtuals from packages.yaml.  Note that because we
     # check spack.repo, this collects virtuals that are actually provided
diff --git a/lib/spack/spack/repository.py b/lib/spack/spack/repository.py
index d22b5e269e..a50f23b609 100644
--- a/lib/spack/spack/repository.py
+++ b/lib/spack/spack/repository.py
@@ -363,7 +363,7 @@ class RepoPath(object):
         # If repo_dirs is empty, just use the configuration
         if not repo_dirs:
             import spack.config
-            repo_dirs = spack.config.get_config('repos')
+            repo_dirs = spack.config.get('repos')
             if not repo_dirs:
                 raise NoRepoConfiguredError(
                     "Spack configuration contains no package repositories.")
diff --git a/lib/spack/spack/stage.py b/lib/spack/spack/stage.py
index b119a874bb..c4acebf1de 100644
--- a/lib/spack/spack/stage.py
+++ b/lib/spack/spack/stage.py
@@ -84,8 +84,7 @@ def get_tmp_root():
         return None
 
     if _tmp_root is None:
-        config = spack.config.get_config('config')
-        candidates = config['build_stage']
+        candidates = spack.config.get('config:build_stage')
         if isinstance(candidates, string_types):
             candidates = [candidates]
 
@@ -378,7 +377,7 @@ class Stage(object):
         # TODO: CompositeFetchStrategy here.
         self.skip_checksum_for_mirror = True
         if self.mirror_path:
-            mirrors = spack.config.get_config('mirrors')
+            mirrors = spack.config.get('mirrors')
 
             # Join URLs of mirror roots with mirror paths. Because
             # urljoin() will strip everything past the final '/' in
@@ -652,7 +651,7 @@ class DIYStage(object):
 
 def _get_mirrors():
     """Get mirrors from spack configuration."""
-    config = spack.config.get_config('mirrors')
+    config = spack.config.get('mirrors')
     return [val for name, val in iteritems(config)]
 
 
diff --git a/lib/spack/spack/store.py b/lib/spack/spack/store.py
index 5b16fd45d6..ca6eb37361 100644
--- a/lib/spack/spack/store.py
+++ b/lib/spack/spack/store.py
@@ -54,15 +54,10 @@ __author__ = "Benedikt Hegner (CERN)"
 __all__ = ['db', 'extensions', 'layout', 'root']
 
 #
-# Read in the config
-#
-config = spack.config.get_config("config")
-
-#
 # Set up the install path
 #
-root = canonicalize_path(
-    config.get('install_tree', os.path.join(spack.paths.opt_path, 'spack')))
+root = canonicalize_path(spack.config.get(
+    'config:install_tree', os.path.join(spack.paths.opt_path, 'spack')))
 
 #
 # Set up the installed packages database
@@ -73,8 +68,9 @@ db = Database(root)
 # This controls how spack lays out install prefixes and
 # stage directories.
 #
-layout = YamlDirectoryLayout(root,
-                             hash_len=config.get('install_hash_length'),
-                             path_scheme=config.get('install_path_scheme'))
+layout = YamlDirectoryLayout(
+    root,
+    hash_len=spack.config.get('config:install_hash_length'),
+    path_scheme=spack.config.get('config:install_path_scheme'))
 
 extensions = YamlExtensionsLayout(root, layout)
diff --git a/lib/spack/spack/test/concretize_preferences.py b/lib/spack/spack/test/concretize_preferences.py
index 5afa51cbe3..7df20830df 100644
--- a/lib/spack/spack/test/concretize_preferences.py
+++ b/lib/spack/spack/test/concretize_preferences.py
@@ -51,7 +51,7 @@ def concretize(abstract_spec):
 def update_packages(pkgname, section, value):
     """Update config and reread package list"""
     conf = {pkgname: {section: value}}
-    spack.config.update_config('packages', conf, 'concretize')
+    spack.config.set('packages', conf, scope='concretize')
     spack.package_prefs.PackagePrefs.clear_caches()
 
 
@@ -133,7 +133,7 @@ mpi:
     paths:
       mpi-with-lapack@2.1: /path/to/lapack
 """)
-        spack.config.update_config('packages', conf, 'concretize')
+        spack.config.set('packages', conf, scope='concretize')
 
         # now when we get the packages.yaml config, there should be an error
         with pytest.raises(spack.package_prefs.VirtualInPackagesYAMLError):
@@ -145,7 +145,7 @@ mpi:
 all:
         variants: [+mpi]
 """)
-        spack.config.update_config('packages', conf, 'concretize')
+        spack.config.set('packages', conf, scope='concretize')
 
         # should be no error for 'all':
         spack.package_prefs.PackagePrefs.clear_caches()
@@ -167,7 +167,7 @@ mpich:
     paths:
         mpich@3.0.4: /dummy/path
 """)
-        spack.config.update_config('packages', conf, 'concretize')
+        spack.config.set('packages', conf, scope='concretize')
 
         # ensure that once config is in place, external is used
         spec = Spec('mpi')
diff --git a/lib/spack/spack/test/config.py b/lib/spack/spack/test/config.py
index 41b02d493e..1021380c88 100644
--- a/lib/spack/spack/test/config.py
+++ b/lib/spack/spack/test/config.py
@@ -85,7 +85,7 @@ def write_config_file(tmpdir):
 
 def check_compiler_config(comps, *compiler_names):
     """Check that named compilers in comps match Spack's config."""
-    config = spack.config.get_config('compilers')
+    config = spack.config.get('compilers')
     compiler_list = ['cc', 'cxx', 'f77', 'fc']
     flag_list = ['cflags', 'cxxflags', 'fflags', 'cppflags',
                  'ldflags', 'ldlibs']
@@ -228,12 +228,8 @@ def compiler_specs():
 
 def test_write_key_in_memory(config, compiler_specs):
     # Write b_comps "on top of" a_comps.
-    spack.config.update_config(
-        'compilers', a_comps['compilers'], scope='low'
-    )
-    spack.config.update_config(
-        'compilers', b_comps['compilers'], scope='high'
-    )
+    spack.config.set('compilers', a_comps['compilers'], scope='low')
+    spack.config.set('compilers', b_comps['compilers'], scope='high')
 
     # Make sure the config looks how we expect.
     check_compiler_config(a_comps['compilers'], *compiler_specs.a)
@@ -242,15 +238,11 @@ def test_write_key_in_memory(config, compiler_specs):
 
 def test_write_key_to_disk(config, compiler_specs):
     # Write b_comps "on top of" a_comps.
-    spack.config.update_config(
-        'compilers', a_comps['compilers'], scope='low'
-    )
-    spack.config.update_config(
-        'compilers', b_comps['compilers'], scope='high'
-    )
+    spack.config.set('compilers', a_comps['compilers'], scope='low')
+    spack.config.set('compilers', b_comps['compilers'], scope='high')
 
     # Clear caches so we're forced to read from disk.
-    spack.config.get_configuration().clear_caches()
+    spack.config.config().clear_caches()
 
     # Same check again, to ensure consistency.
     check_compiler_config(a_comps['compilers'], *compiler_specs.a)
@@ -259,15 +251,11 @@ def test_write_key_to_disk(config, compiler_specs):
 
 def test_write_to_same_priority_file(config, compiler_specs):
     # Write b_comps in the same file as a_comps.
-    spack.config.update_config(
-        'compilers', a_comps['compilers'], scope='low'
-    )
-    spack.config.update_config(
-        'compilers', b_comps['compilers'], scope='low'
-    )
+    spack.config.set('compilers', a_comps['compilers'], scope='low')
+    spack.config.set('compilers', b_comps['compilers'], scope='low')
 
     # Clear caches so we're forced to read from disk.
-    spack.config.get_configuration().clear_caches()
+    spack.config.config().clear_caches()
 
     # Same check again, to ensure consistency.
     check_compiler_config(a_comps['compilers'], *compiler_specs.a)
@@ -283,10 +271,10 @@ repos_high = {'repos': ["/some/other/path"]}
 
 # repos
 def test_write_list_in_memory(config):
-    spack.config.update_config('repos', repos_low['repos'], scope='low')
-    spack.config.update_config('repos', repos_high['repos'], scope='high')
+    spack.config.set('repos', repos_low['repos'], scope='low')
+    spack.config.set('repos', repos_high['repos'], scope='high')
 
-    config = spack.config.get_config('repos')
+    config = spack.config.get('repos')
     assert config == repos_high['repos'] + repos_low['repos']
 
 
@@ -359,7 +347,7 @@ def test_merge_with_defaults(config, write_config_file):
     """
     write_config_file('packages', packages_merge_low, 'low')
     write_config_file('packages', packages_merge_high, 'high')
-    cfg = spack.config.get_config('packages')
+    cfg = spack.config.get('packages')
 
     assert cfg['foo']['version'] == ['a']
     assert cfg['bar']['version'] == ['b']
@@ -383,13 +371,13 @@ def test_substitute_tempdir(config):
 
 def test_read_config(config, write_config_file):
     write_config_file('config', config_low, 'low')
-    assert spack.config.get_config('config') == config_low['config']
+    assert spack.config.get('config') == config_low['config']
 
 
 def test_read_config_override_all(config, write_config_file):
     write_config_file('config', config_low, 'low')
     write_config_file('config', config_override_all, 'high')
-    assert spack.config.get_config('config') == {
+    assert spack.config.get('config') == {
         'install_tree': 'override_all'
     }
 
@@ -397,7 +385,7 @@ def test_read_config_override_all(config, write_config_file):
 def test_read_config_override_key(config, write_config_file):
     write_config_file('config', config_low, 'low')
     write_config_file('config', config_override_key, 'high')
-    assert spack.config.get_config('config') == {
+    assert spack.config.get('config') == {
         'install_tree': 'override_key',
         'build_stage': ['path1', 'path2', 'path3']
     }
@@ -406,7 +394,7 @@ def test_read_config_override_key(config, write_config_file):
 def test_read_config_merge_list(config, write_config_file):
     write_config_file('config', config_low, 'low')
     write_config_file('config', config_merge_list, 'high')
-    assert spack.config.get_config('config') == {
+    assert spack.config.get('config') == {
         'install_tree': 'install_tree_path',
         'build_stage': ['patha', 'pathb', 'path1', 'path2', 'path3']
     }
@@ -415,7 +403,7 @@ def test_read_config_merge_list(config, write_config_file):
 def test_read_config_override_list(config, write_config_file):
     write_config_file('config', config_low, 'low')
     write_config_file('config', config_override_list, 'high')
-    assert spack.config.get_config('config') == {
+    assert spack.config.get('config') == {
         'install_tree': 'install_tree_path',
         'build_stage': ['patha', 'pathb']
     }
@@ -424,30 +412,30 @@ def test_read_config_override_list(config, write_config_file):
 def test_internal_config_update(config, write_config_file):
     write_config_file('config', config_low, 'low')
 
-    before = config.get_config('config')
+    before = config.get('config')
     assert before['install_tree'] == 'install_tree_path'
 
     # add an internal configuration scope
-    scope = spack.config.InternalConfigScope('commands')
+    scope = spack.config.InternalConfigScope('command_line')
     assert 'InternalConfigScope' in repr(scope)
 
     config.push_scope(scope)
 
-    command_config = config.get_config('config', scope='commands')
+    command_config = config.get('config', scope='command_line')
     command_config['install_tree'] = 'foo/bar'
 
-    config.update_config('config', command_config, scope='commands')
+    config.set('config', command_config, scope='command_line')
 
-    after = config.get_config('config')
+    after = config.get('config')
     assert after['install_tree'] == 'foo/bar'
 
 
 def test_internal_config_filename(config, write_config_file):
     write_config_file('config', config_low, 'low')
-    config.push_scope(spack.config.InternalConfigScope('commands'))
+    config.push_scope(spack.config.InternalConfigScope('command_line'))
 
     with pytest.raises(NotImplementedError):
-        config.get_config_filename('commands', 'config')
+        config.get_config_filename('command_line', 'config')
 
 
 def test_keys_are_ordered():
diff --git a/lib/spack/spack/test/mirror.py b/lib/spack/spack/test/mirror.py
index 014f0e5031..feda91e713 100644
--- a/lib/spack/spack/test/mirror.py
+++ b/lib/spack/spack/test/mirror.py
@@ -69,7 +69,7 @@ def check_mirror():
         mirror_root = join_path(stage.path, 'test-mirror')
         # register mirror with spack config
         mirrors = {'spack-mirror-test': 'file://' + mirror_root}
-        spack.config.update_config('mirrors', mirrors)
+        spack.config.set('mirrors', mirrors)
         spack.mirror.create(mirror_root, repos, no_checksum=True)
 
         # Stage directory exists
diff --git a/lib/spack/spack/test/modules/conftest.py b/lib/spack/spack/test/modules/conftest.py
index b08a943c72..6fb9a4d368 100644
--- a/lib/spack/spack/test/modules/conftest.py
+++ b/lib/spack/spack/test/modules/conftest.py
@@ -93,7 +93,7 @@ def modulefile_content(filename_dict, request):
 @pytest.fixture()
 def update_template_dirs(config, monkeypatch):
     """Mocks the template directories for tests"""
-    dirs = spack.config.get_config('config')['template_dirs']
+    dirs = spack.config.get('config:template_dirs')
     dirs = [spack.util.path.canonicalize_path(x) for x in dirs]
     monkeypatch.setattr(spack, 'template_dirs', dirs)
 
diff --git a/lib/spack/spack/test/package_sanity.py b/lib/spack/spack/test/package_sanity.py
index 30c6794c2a..747552df97 100644
--- a/lib/spack/spack/test/package_sanity.py
+++ b/lib/spack/spack/test/package_sanity.py
@@ -64,7 +64,7 @@ def test_all_versions_are_lowercase():
 
 def test_all_virtual_packages_have_default_providers():
     """All virtual packages must have a default provider explicitly set."""
-    defaults = spack.config.get_config('packages', scope='defaults')
+    defaults = spack.config.get('packages', scope='defaults')
     default_providers = defaults['all']['providers']
     providers = spack.repo.provider_index.providers
 
diff --git a/lib/spack/spack/test/packaging.py b/lib/spack/spack/test/packaging.py
index 3cedec3955..30bff20213 100644
--- a/lib/spack/spack/test/packaging.py
+++ b/lib/spack/spack/test/packaging.py
@@ -114,7 +114,7 @@ echo $PATH"""
 
     # register mirror with spack config
     mirrors = {'spack-mirror-test': 'file://' + mirror_path}
-    spack.config.update_config('mirrors', mirrors)
+    spack.config.set('mirrors', mirrors)
 
     stage = spack.stage.Stage(
         mirrors['spack-mirror-test'], name="build_cache", keep=True)
@@ -213,7 +213,7 @@ echo $PATH"""
 
     # unregister mirror with spack config
     mirrors = {}
-    spack.config.update_config('mirrors', mirrors)
+    spack.config.set('mirrors', mirrors)
     shutil.rmtree(mirror_path)
     stage.destroy()
 
diff --git a/lib/spack/spack/test/stage.py b/lib/spack/spack/test/stage.py
index 966c97ab5f..6edd47e5bf 100644
--- a/lib/spack/spack/test/stage.py
+++ b/lib/spack/spack/test/stage.py
@@ -114,15 +114,12 @@ def get_stage_path(stage, stage_name):
 def tmpdir_for_stage(mock_archive):
     """Uses a temporary directory for staging"""
     current = spack.paths.stage_path
-    spack.config.update_config(
+    spack.config.set(
         'config',
         {'build_stage': [str(mock_archive.test_tmp_dir)]},
-        scope='user'
-    )
+        scope='user')
     yield
-    spack.config.update_config(
-        'config', {'build_stage': [current]}, scope='user'
-    )
+    spack.config.set('config', {'build_stage': [current]}, scope='user')
 
 
 @pytest.fixture()
@@ -138,9 +135,8 @@ def mock_archive(tmpdir, monkeypatch):
     #
     test_tmp_path = tmpdir.join('tmp')
     # set _test_tmp_path as the default test directory to use for stages.
-    spack.config.update_config(
-        'config', {'build_stage': [str(test_tmp_path)]}, scope='user'
-    )
+    spack.config.set(
+        'config', {'build_stage': [str(test_tmp_path)]}, scope='user')
 
     archive_dir = tmpdir.join('test-files')
     archive_name = 'test-files.tar.gz'
diff --git a/lib/spack/spack/test/tengine.py b/lib/spack/spack/test/tengine.py
index 8af70655f0..5cfcb6d3df 100644
--- a/lib/spack/spack/test/tengine.py
+++ b/lib/spack/spack/test/tengine.py
@@ -91,7 +91,7 @@ class TestTengineEnvironment(object):
     def test_template_retrieval(self):
         """Tests the template retrieval mechanism hooked into config files"""
         # Check the directories are correct
-        template_dirs = spack.config.get_config('config')['template_dirs']
+        template_dirs = spack.config.get('config:template_dirs')
         template_dirs = [canonicalize_path(x) for x in template_dirs]
         assert len(template_dirs) == 3
 
diff --git a/share/spack/setup-env.csh b/share/spack/setup-env.csh
index b17b753bbe..0f67ef7906 100755
--- a/share/spack/setup-env.csh
+++ b/share/spack/setup-env.csh
@@ -41,8 +41,8 @@ if ($?SPACK_ROOT) then
 
     # Shamelessly stolen from setup-env.sh
     set _sp_sys_type    = `$SPACK_ROOT/bin/spack python -c 'print(spack.architecture.sys_type())'`
-    set _sp_dotkit_root = `$SPACK_ROOT/bin/spack python -c "print(spack.util.path.canonicalize_path(spack.config.get_config('config').get('module_roots').get('dotkit')))"`
-    set _sp_tcl_root    = `$SPACK_ROOT/bin/spack python -c "print(spack.util.path.canonicalize_path(spack.config.get_config('config').get('module_roots').get('tcl')))"`
+    set _sp_dotkit_root = `$SPACK_ROOT/bin/spack python -c "print(spack.util.path.canonicalize_path(spack.config.get('config:module_roots', {}).get('dotkit')))"`
+    set _sp_tcl_root    = `$SPACK_ROOT/bin/spack python -c "print(spack.util.path.canonicalize_path(spack.config.get('config:module_roots', {}).get('tcl')))"`
 
     # Set up modules and dotkit search paths in the user environment
     _spack_pathadd DK_NODE    "$_sp_dotkit_root/$_sp_sys_type"
diff --git a/share/spack/setup-env.sh b/share/spack/setup-env.sh
index 1dbc49c8a7..b983299975 100755
--- a/share/spack/setup-env.sh
+++ b/share/spack/setup-env.sh
@@ -239,8 +239,8 @@ fi;
 
 _python_command=$(printf  "%s\\\n%s\\\n%s" \
 "print(\'_sp_sys_type={0}\'.format(spack.architecture.sys_type()))" \
-"print(\'_sp_dotkit_root={0}\'.format(spack.util.path.canonicalize_path(spack.config.get_config(\'config\').get(\'module_roots\', {}).get(\'dotkit\'))))" \
-"print(\'_sp_tcl_root={0}\'.format(spack.util.path.canonicalize_path(spack.config.get_config(\'config\').get(\'module_roots\', {}).get(\'tcl\'))))"
+"print(\'_sp_dotkit_root={0}\'.format(spack.util.path.canonicalize_path(spack.config.get(\'config:module_roots\', {}).get(\'dotkit\'))))" \
+"print(\'_sp_tcl_root={0}\'.format(spack.util.path.canonicalize_path(spack.config.get(\'config:module_roots\', {}).get(\'tcl\'))))"
 )
 
 _assignment_command=$(spack-python -c "exec('${_python_command}')")