SK-1863: Added migration from v1 to v2 guide to readme

Author: saileshwar-skyflow

README.md

@@ -16,6 +16,7 @@ This Python SDK is designed to help developers easily implement Skyflow into the
     - [Requirements](#requirements)
     - [Configuration](#configuration)
   - [Service Account Bearer Token Generation](#service-account-bearer-token-generation)
+  [Migration from v1 to v2](#migrate-from-v1-to-v2)
   - [Vault APIs](#vault-apis)
     - [Insert data into the vault](#insert-data-into-the-vault)
     - [Detokenize](#detokenize)
@@ -328,6 +329,250 @@ try:
 except SkyflowError as e:
     print(e)
 ```
+## Migrate from V1 to V2
+
+Below are the steps to migrate the Python SDK from V1 to V2.
+
+### 1. Authentication Options
+
+In V2, we have introduced multiple authentication options. 
+You can now provide credentials in the following ways: 
+
+1. **API Key (Recommended)**
+2. **Environment Variables** (SKYFLOW_CREDENTIALS) (Recommended)
+3. **Path to your credentials JSON file**
+4. **Stringified JSON of your credentials**
+5. **Bearer token**
+
+These options allow you to choose the authentication method that best suits your use case.
+
+#### V1 (Old):
+Passing the token provider function below as a parameter to the Configuration.
+
+```python
+# User defined function to provide access token to the vault apis
+def token_provider():
+    global bearerToken
+    if !(is_expired(bearerToken)):
+        return bearerToken
+    bearerToken, _ = generate_bearer_token('<YOUR_CREDENTIALS_FILE_PATH>')
+    return bearerToken
+```
+
+#### V2 (New):
+Passing one of the following:
+
+```python
+# Option 1: API Key (Recommended)
+credentials = {
+    'api_key': '<your_api_key>', # API key
+}
+
+# Option 2: Environment Variables (Recommended)
+# Set SKYFLOW_CREDENTIALS in your environment
+
+# Option 3: Credentials File
+credentials = {
+    'path': '<path_to_credentials_json>', # Path to credentials file
+}
+
+# Option 4: Stringified JSON
+credentials = {
+    'credentials_string': '<your_credentials_string>', # Credentials as string
+}
+
+# Option 5: Bearer Token
+credentials = {
+    'token': '<your_bearer_token>', # Bearer token
+}
+```
+
+**Notes:**
+1. Use only ONE authentication method.
+2. Environment variables take precedence over programmatic configuration.
+3. API Key or Environment Variables are recommended for production use.
+4. Secure storage of credentials is essential.
+5. For overriding behavior and priority order of credentials, please refer to the README.
+
+### 2. Client Initialization
+
+In V2, we have introduced a Builder design pattern for client initialization and added support for multi-vault. This allows you to configure multiple vaults during client initialization. 
+
+In V2, the log level is tied to each individual client instance. 
+
+During client initialization, you can pass the following parameters:
+
+1. **vault_id** and **cluster_id**: These values are derived from the vault ID & vault URL.
+2. **env**: Specify the environment (e.g., SANDBOX or PROD).
+3. **credentials**: The necessary authentication credentials.
+
+#### V1 (Old):
+
+```python
+# Initializing a Skyflow Client instance with a SkyflowConfiguration object
+config = Configuration('<YOUR_VAULT_ID>', '<YOUR_VAULT_URL>', token_provider)
+client = Client(config)
+```
+
+#### V2 (New):
+
+```python
+# Initializing a Skyflow Client instance
+client = (
+    Skyflow.builder()
+    .add_vault_config({
+           'vault_id': 'VAULT_ID', # Primary vault
+           'cluster_id': 'CLUSTER_ID', # ID from your vault URL e.g., https://{clusterId}.vault.skyflowapis.com
+           'env': Env.PROD, # Env by default it is set to PROD
+           'credentials': credentials # Individual credentials
+    })
+    .add_skyflow_credentials(credentials) # Skyflow credentials will be used if no individual credentials are passed
+    .set_log_level(LogLevel.INFO) # set log level by default it is set to ERROR
+    .build()
+)
+```
+
+**Key Changes:**
+1. `vault_url` replaced with `clusterId`.
+2. Added environment specification (`env`).
+3. Instance-specific log levels.
+
+### 3. Request & Response Structure
+
+In V2, with the introduction of constructor parameters, you can now pass parameters to `InsertRequest`. This request need 
+- **table_name**: The name of the table.
+- **values**: An array of objects containing the data to be inserted.
+The response will be of type `InsertResponse` class, which contains `inserted_fields` and errors.
+
+#### V1 (Old): Request Building
+
+```python
+client.insert(
+    {
+        "records": [
+            {
+                "table": "cards",
+                "fields": {
+                    "cardNumber": "41111111111",
+                    "cvv": "123",
+                },
+            }
+        ]
+    },
+    InsertOptions(True),
+)
+```
+
+#### V2 (New): Request Building
+
+```python
+# Prepare Insertion Data
+insert_data = [
+   {
+       'card_number': '<VALUE1>',
+       'cvv': '<VALUE2>',
+   },
+]
+
+table_name = '<SENSITIVE_DATA_TABLE>' # Replace with your actual table name
+
+# Create Insert Request
+insert_request = InsertRequest(
+   table_name=table_name,
+   values=insert_data,
+   return_tokens=True, # Optional: Get tokens for inserted data
+   continue_on_error=True # Optional: Continue on partial errors
+)
+
+# Perform Secure Insertion
+response = skyflow_client.vault(primary_vault_config.get('vault_id')).insert(insert_request)
+```
+
+#### V1 (Old): Response Structure
+
+```json
+{
+    "records": [
+        {
+            "table": "cards",
+            "fields": {
+                "cardNumber": "f3907186-e7e2-466f-91e5-48e12c2bcbc1",
+                "cvv": "1989cb56-63da-4482-a2df-1f74cd0dd1a5",
+                "skyflow_id": "d863633c-8c75-44fc-b2ed-2b58162d1117"
+            },
+            "request_index": 0
+        }
+    ]
+}
+```
+
+#### V2 (New): Response Structure
+
+```python
+InsertResponse(
+   inserted_fields=[
+       {
+           'skyflow_id': 'a8f3ed5d-55eb-4f32-bf7e-2dbf4b9d9097',
+           'card_number': '5479-4229-4622-1393'
+       }
+   ],
+   errors=[]
+)
+```
+
+### 4. Request Options
+
+In V2, we have introduced constructor parameters, allowing you to set options as key-value pairs as parameters in request.
+
+#### V1 (Old):
+
+```python
+options = InsertOptions(
+    tokens = True
+)
+```
+
+#### V2 (New):
+
+```python
+insert_request = InsertRequest(
+   table_name=table_name,
+   values=insert_data,
+   return_tokens=True, # Optional: Get tokens for inserted data
+   continue_on_error=True # Optional: Continue on partial errors
+)
+```
+
+### 5. Request Options
+
+In V2, we have enriched the error details to provide better debugging capabilities. 
+The error response now includes: 
+- **http_status**: The HTTP status code. 
+- **grpc_code**: The gRPC code associated with the error. 
+- **details & message**: A detailed description of the error. 
+- **request_id**: A unique request identifier for easier debugging.
+
+#### V1 (Old) Error Structure:
+
+```json
+{
+  "code": "<http_code>",
+  "message": "<message>"
+}
+```
+
+#### V2 (New) Error Structure:
+
+```json
+{
+    "http_status": "<http_status>",
+    "grpc_code": "<grpc_code>",
+    "http_code": "<http_code>",
+    "message": "<message>",
+    "request_id": "<req_id>",
+    "details": [ "<details>" ]
+}
+```
 
 ## Vault APIs