Simplify passing host configuration direct to Index client (#280)

## Problem

In production situations, it's important people be able to configure the
client in a way that does not hit the control plane to find out the host
url. This was possible, but now that I'm writing docs I realized this is
cumbersome because the positional index name arg was still being
required even though it wasn't being used in that scenario.

We want it to be easy.

## Solution

### Before

```python
from pinecone.grpc import PineconeGRPC

pc = PineconeGRPC(api_key="key")

# Targeting by name is easy
index = pc.Index('blah')

# Targeting by host url is awkward
index = pc.Index('required-but-unused-index-name', host='blah-24vnhz6.svc.apw5-4e34-81fa.pinecone.io')
```

### After

```python
from pinecone.grpc import PineconeGRPC

pc = PineconeGRPC(api_key="key")

# This still works
index = pc.Index('blah')

# This now works
index = pc.Index(host='blah-24vnhz6.svc.apw5-4e34-81fa.pinecone.io')

# Or pass both if you really want, but not needed.
index = pc.Index(name='blah', host='blah-24vnhz6.svc.apw5-4e34-81fa.pinecone.io')
```

## Type of Change

- [x] New feature (non-breaking change which adds functionality)

## Test Plan

Update integration tests to check it can still issue data calls without
errors no matter how it is configured.

pinecone/control/pinecone.py

@@ -7,7 +7,7 @@
 
 from pinecone.core.client.api.manage_indexes_api import ManageIndexesApi as IndexOperationsApi
 from pinecone.core.client.api_client import ApiClient
-from pinecone.utils import get_user_agent
+from pinecone.utils import get_user_agent, normalize_host
 from pinecone.core.client.models import (
     CreateCollectionRequest,
     CreateIndexRequest,
@@ -213,7 +213,15 @@ def _get_status(self, name: str):
         response = api_instance.describe_index(name)
         return response["status"]
 
-    def Index(self, name: str, host: Optional[str] = None):
-        if host is None:
-            host = self.index_host_store.get_host(self.index_api, self.config, name)
-        return Index(api_key=self.config.api_key, host=host, pool_threads=self.pool_threads)
+    def Index(self, name: str = '', host: str = ''):
+        if name == '' and host == '':
+            raise ValueError("Either name or host must be specified")
+
+        if host != '':
+            # Use host url if it is provided
+            return Index(api_key=self.config.api_key, host=normalize_host(host), pool_threads=self.pool_threads)
+
+        if name != '':
+            # Otherwise, get host url from describe_index using the index name
+            index_host = self.index_host_store.get_host(self.index_api, self.config, name)
+            return Index(api_key=self.config.api_key, host=index_host, pool_threads=self.pool_threads)

pinecone/grpc/pinecone.py

@@ -1,11 +1,19 @@
 from ..control.pinecone import Pinecone
 from ..config.config import ConfigBuilder
 from .index_grpc import GRPCIndex
-from typing import Optional
 
 class PineconeGRPC(Pinecone):
-    def Index(self, name: str, host: Optional[str] = None):
-        if host is None:
-            host = self.index_host_store.get_host(self.index_api, self.config, name)
-        config = ConfigBuilder.build(api_key=self.config.api_key, host=host)
-        return GRPCIndex(index_name=name, config=config)
+    def Index(self, name: str = '', host: str = ''):
+        if name == '' and host == '':
+            raise ValueError("Either name or host must be specified")
+
+        if host != '':
+            # Use host if it is provided
+            config = ConfigBuilder.build(api_key=self.config.api_key, host=host)
+            return GRPCIndex(index_name=name, config=config)
+
+        if name != '':
+            # Otherwise, get host url from describe_index using the index name
+            index_host = self.index_host_store.get_host(self.index_api, self.config, name)
+            config = ConfigBuilder.build(api_key=self.config.api_key, host=index_host)
+            return GRPCIndex(index_name=name, config=config)

tests/integration/data/test_initialization.py

@@ -0,0 +1,38 @@
+import pytest
+
+class TestIndexClientInitialization:
+    def test_index_direct_host_kwarg(self, client, index_host):
+        index = client.Index(host=index_host)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_direct_host_with_https(self, client, index_host):
+        if not index_host.startswith('https://'):
+            index_host = 'https://' + index_host
+        index = client.Index(host=index_host)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_direct_host_without_https(self, client, index_host):
+        if index_host.startswith('https://'):
+            index_host = index_host[8:]
+        index = client.Index(host=index_host)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_by_name_positional_only(self, client, index_name, index_host):
+        index = client.Index(index_name)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_by_name_positional_with_host(self, client, index_name, index_host):
+        index = client.Index(index_name, index_host)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_by_name_kwargs(self, client, index_name):
+        index = client.Index(name=index_name)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_index_by_name_kwargs_with_host(self, client, index_name, index_host):
+        index = client.Index(name=index_name, host=index_host)
+        index.fetch(ids=['1', '2', '3'])
+
+    def test_raises_when_no_name_or_host(self, client, index_host):
+        with pytest.raises(ValueError):
+            client.Index()