Merging 0.15.3 into dev/barbara-gittings broke the branch
### Describe the bug
The integration tests came in, 0.15.3 actual code did not come in, unit tests passed so I merged... oops.

### Steps To Reproduce
Try to run the snowflake tests, get an oauth failure.

### Expected behavior
I expect the code to come in

### Screenshots and log output
N/A

### System information
N/A

diff --git a/plugins/snowflake/dbt/adapters/snowflake/connections.py b/plugins/snowflake/dbt/adapters/snowflake/connections.py
index e6b60d1fa..826dfb154 100644
--- a/plugins/snowflake/dbt/adapters/snowflake/connections.py
+++ b/plugins/snowflake/dbt/adapters/snowflake/connections.py
@@ -1,3 +1,4 @@
+import base64
 import datetime
 import pytz
 import re
@@ -8,15 +9,22 @@ from typing import Optional
 
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import serialization
+import requests
 import snowflake.connector
 import snowflake.connector.errors
 
-import dbt.exceptions
+from dbt.exceptions import (
+    InternalException, RuntimeException, FailedToConnectException,
+    DatabaseException, warn_or_error
+)
 from dbt.adapters.base import Credentials
 from dbt.adapters.sql import SQLConnectionManager
 from dbt.logger import GLOBAL_LOGGER as logger
 
 
+_TOKEN_REQUEST_URL = 'https://{}.snowflakecomputing.com/oauth/token-request'
+
+
 @dataclass
 class SnowflakeCredentials(Credentials):
     account: str
@@ -28,15 +36,30 @@ class SnowflakeCredentials(Credentials):
     private_key_path: Optional[str]
     private_key_passphrase: Optional[str]
     token: Optional[str]
+    oauth_client_id: Optional[str]
+    oauth_client_secret: Optional[str]
     client_session_keep_alive: bool = False
 
+    def __post_init__(self):
+        if (
+            self.authenticator != 'oauth' and
+            (self.oauth_client_secret or self.oauth_client_id or self.token)
+        ):
+            # the user probably forgot to set 'authenticator' like I keep doing
+            warn_or_error(
+                'Authenticator is not set to oauth, but an oauth-only '
+                'parameter is set! Did you mean to set authenticator: oauth?'
+            )
+
     @property
     def type(self):
         return 'snowflake'
 
     def _connection_keys(self):
-        return ('account', 'user', 'database', 'schema', 'warehouse', 'role',
-                'client_session_keep_alive')
+        return (
+            'account', 'user', 'database', 'schema', 'warehouse', 'role',
+            'client_session_keep_alive'
+        )
 
     def auth_args(self):
         # Pull all of the optional authentication args for the connector,
@@ -47,10 +70,63 @@ class SnowflakeCredentials(Credentials):
         if self.authenticator:
             result['authenticator'] = self.authenticator
             if self.authenticator == 'oauth':
-                result['token'] = self.token
+                token = self.token
+                # if we have a client ID/client secret, the token is a refresh
+                # token, not an access token
+                if self.oauth_client_id and self.oauth_client_secret:
+                    token = self._get_access_token()
+                elif self.oauth_client_id:
+                    warn_or_error(
+                        'Invalid profile: got an oauth_client_id, but not an '
+                        'oauth_client_secret!'
+                    )
+                elif self.oauth_client_secret:
+                    warn_or_error(
+                        'Invalid profile: got an oauth_client_secret, but not '
+                        'an oauth_client_id!'
+                    )
+
+                result['token'] = token
         result['private_key'] = self._get_private_key()
         return result
 
+    def _get_access_token(self) -> str:
+        if self.authenticator != 'oauth':
+            raise InternalException('Can only get access tokens for oauth')
+        missing = any(
+            x is None for x in
+            (self.oauth_client_id, self.oauth_client_secret, self.token)
+        )
+        if missing:
+            raise InternalException(
+                'need a client ID a client secret, and a refresh token to get '
+                'an access token'
+            )
+        # should the full url be a config item?
+        token_url = _TOKEN_REQUEST_URL.format(self.account)
+        # I think this is only used to redirect on success, which we ignore
+        # (it does not have to match the integration's settings in snowflake)
+        redirect_uri = 'http://localhost:9999'
+        data = {
+            'grant_type': 'refresh_token',
+            'refresh_token': self.token,
+            'redirect_uri': redirect_uri
+        }
+
+        auth = base64.b64encode(
+            f'{self.oauth_client_id}:{self.oauth_client_secret}'
+            .encode('ascii')
+        ).decode('ascii')
+        headers = {
+            'Authorization': f'Basic {auth}',
+            'Content-type': 'application/x-www-form-urlencoded;charset=utf-8'
+        }
+        result = requests.post(token_url, headers=headers, data=data)
+        result_json = result.json()
+        if 'access_token' not in result_json:
+            raise DatabaseException(f'Did not get a token: {result_json}')
+        return result_json['access_token']
+
     def _get_private_key(self):
         """Get Snowflake private key by path or None."""
         if not self.private_key_path or self.private_key_passphrase is None:
@@ -84,7 +160,7 @@ class SnowflakeConnectionManager(SQLConnectionManager):
                 logger.debug("got empty sql statement, moving on")
             elif 'This session does not have a current database' in msg:
                 self.release()
-                raise dbt.exceptions.FailedToConnectException(
+                raise FailedToConnectException(
                     ('{}\\n\\nThis error sometimes occurs when invalid '
                      'credentials are provided, or when your default role '
                      'does not have access to use the specified database. '
@@ -92,17 +168,17 @@ class SnowflakeConnectionManager(SQLConnectionManager):
                     .format(msg))
             else:
                 self.release()
-                raise dbt.exceptions.DatabaseException(msg)
+                raise DatabaseException(msg)
         except Exception as e:
             logger.debug("Error running SQL: {}", sql)
             logger.debug("Rolling back transaction.")
             self.release()
-            if isinstance(e, dbt.exceptions.RuntimeException):
+            if isinstance(e, RuntimeException):
                 # during a sql query, an internal to dbt exception was raised.
                 # this sounds a lot like a signal handler and probably has
                 # useful information, so raise it without modification.
                 raise
-            raise dbt.exceptions.RuntimeException(str(e)) from e
+            raise RuntimeException(str(e)) from e
 
     @classmethod
     def open(cls, connection):
@@ -136,7 +212,7 @@ class SnowflakeConnectionManager(SQLConnectionManager):
             connection.handle = None
             connection.state = 'fail'
 
-            raise dbt.exceptions.FailedToConnectException(str(e))
+            raise FailedToConnectException(str(e))
 
     def cancel(self, connection):
         handle = connection.handle
@@ -228,7 +304,7 @@ class SnowflakeConnectionManager(SQLConnectionManager):
             else:
                 conn_name = conn.name
 
-            raise dbt.exceptions.RuntimeException(
+            raise RuntimeException(
                 "Tried to run an empty query on model '{}'. If you are "
                 "conditionally running\\nsql, eg. in a model hook, make "
                 "sure your `else` clause contains valid sql!\\n\\n"
['plugins/snowflake/dbt/adapters/snowflake/connections.py']