feat(configtree): supports overrides while import config from files

This commit adds the support for config overrides while importing
configurations from files. Users can specify one or more override
files and they will be applied to the base configs in order. It is
expected that the overrides have the full key hierarchy such that
the command is able to match the right override with the base config.

Wrike Ticket:

riocli/configtree/import_keys.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 from pathlib import Path
-from typing import Optional, Iterable
+from typing import Iterable, Optional
 
 import click
 from benedict import benedict
@@ -23,7 +23,7 @@
 from riocli.configtree.etcd import import_in_etcd
 from riocli.configtree.revision import Revision
 from riocli.configtree.util import Metadata, export_to_files
-from riocli.constants import Symbols, Colors
+from riocli.constants import Colors, Symbols
 from riocli.utils.spinner import with_spinner
 
 
@@ -36,7 +36,7 @@
 @click.option('--commit/--no-commit', 'commit', is_flag=True, type=bool, )
 @click.option('--update-head/--no-update-head', 'update_head', is_flag=True, type=bool)
 @click.option('--milestone', 'milestone', type=str,
-              help='Minestone name for the imported revision.')
+              help='Milestone name for the imported revision.')
 @click.option('--etcd-endpoint', 'etcd_endpoint', type=str,
               help='Import keys to local etcd instead of rapyuta.io cloud')
 @click.option('--export-directory', 'export_directory', type=str,
@@ -47,6 +47,8 @@
               help='Prefix to use for the key-space')
 @click.option('--organization', 'with_org', is_flag=True, type=bool,
               default=False, help='Operate on organization-scoped Config Trees only.')
+@click.option('--override', 'overrides', type=click.Path(exists=True), default=None,
+              multiple=True, help='Override values for keys in the imported files.')
 @click.argument('tree-name', type=str)
 @click.argument('files', type=str, nargs=-1)
 @click.pass_context
@@ -62,13 +64,13 @@ def import_keys(
         etcd_endpoint: Optional[str],
         etcd_port: Optional[int],
         etcd_prefix: Optional[str],
+        overrides: Optional[Iterable[click.Path]],
         with_org: bool,
         spinner: Yaspin,
 ) -> None:
     """
     Imports keys in a Config tree from YAML files.
     """
-
     data = {}
 
     for f in files:
@@ -85,6 +87,23 @@ def import_keys(
             )
         )
 
+    for f in overrides:
+        file_format = 'yaml'
+        if f.endswith('json'):
+            file_format = 'json'
+
+        o = benedict(f, format=file_format)
+
+        for file_prefix in data:
+            data[file_prefix].merge(o[file_prefix], overwrite=True)
+
+        spinner.write(
+            click.style(
+                '{} Overrides from file {} applied.'.format(Symbols.SUCCESS, f),
+                fg=Colors.CYAN,
+            )
+        )
+
     data, metadata = split_metadata(data)
 
     if export_directory is not None: