Remove SqlAlchemy dependency from postgres container

Create a new generic database subclass - DependencyFreeDbContainer
Remove test that was testing sqlalchemy support for driver types
Add tests for supported versions of Postgres
Modify the `get_connection_url` convenience method to support a
driverless url

Author: logicbomb

core/testcontainers/core/generic.py

@@ -25,6 +25,37 @@
     pass
 
 
+class DependencyFreeDbContainer(DockerContainer):
+    """
+    A generic database without any package dependencies
+    """
+    def start(self) -> 'DbContainer':
+        self._configure()
+        super().start()
+        self._verify_status()
+        return self
+
+    def _verify_status(self) -> 'DependencyFreeDbContainer':
+        """override this method to ensure the database is running and accepting connections"""
+        raise NotImplementedError
+
+    def _configure(self) -> None:
+        raise NotImplementedError
+
+    def _create_connection_url(self, dialect: str, username: str, password: str,
+                               host: Optional[str] = None, port: Optional[int] = None,
+                               dbname: Optional[str] = None, **kwargs) -> str:
+        if raise_for_deprecated_parameter(kwargs, "db_name", "dbname"):
+            raise ValueError(f"Unexpected arguments: {','.join(kwargs)}")
+        if self._container is None:
+            raise ContainerStartException("container has not been started")
+        host = host or self.get_container_host_ip()
+        port = self.get_exposed_port(port)
+        url = f"{dialect}://{username}:{password}@{host}:{port}"
+        if dbname:
+            url = f"{url}/{dbname}"
+        return url
+
 class DbContainer(DockerContainer):
     """
     Generic database container.

postgres/testcontainers/postgres/__init__.py

@@ -11,12 +11,17 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 import os
+from time import sleep
 from typing import Optional
-from testcontainers.core.generic import DbContainer
+
+from testcontainers.core.config import MAX_TRIES, SLEEP_TIME
+from testcontainers.core.generic import DependencyFreeDbContainer
 from testcontainers.core.utils import raise_for_deprecated_parameter
+from testcontainers.core.waiting_utils import (wait_container_is_ready,
+                                               wait_for_logs)
 
 
-class PostgresContainer(DbContainer):
+class PostgresContainer(DependencyFreeDbContainer):
     """
     Postgres database container.
 
@@ -41,14 +46,14 @@ class PostgresContainer(DbContainer):
     """
     def __init__(self, image: str = "postgres:latest", port: int = 5432,
                  username: Optional[str] = None, password: Optional[str] = None,
-                 dbname: Optional[str] = None, driver: str = "psycopg2", **kwargs) -> None:
+                 dbname: Optional[str] = None, driver: str | None = "psycopg2", **kwargs) -> None:
         raise_for_deprecated_parameter(kwargs, "user", "username")
         super(PostgresContainer, self).__init__(image=image, **kwargs)
-        self.username = username or os.environ.get("POSTGRES_USER", "test")
-        self.password = password or os.environ.get("POSTGRES_PASSWORD", "test")
-        self.dbname = dbname or os.environ.get("POSTGRES_DB", "test")
+        self.username: str = username or os.environ.get("POSTGRES_USER", "test")
+        self.password: str = password or os.environ.get("POSTGRES_PASSWORD", "test")
+        self.dbname: str = dbname or os.environ.get("POSTGRES_DB", "test")
         self.port = port
-        self.driver = driver
+        self.driver = f"+{driver}" if driver else ""
 
         self.with_exposed_ports(self.port)
 
@@ -59,7 +64,22 @@ def _configure(self) -> None:
 
     def get_connection_url(self, host=None) -> str:
         return super()._create_connection_url(
-            dialect=f"postgresql+{self.driver}", username=self.username,
+            dialect=f"postgresql{self.driver}", username=self.username,
             password=self.password, dbname=self.dbname, host=host,
             port=self.port,
         )
+
+    @wait_container_is_ready()
+    def _verify_status(self) -> None:
+        wait_for_logs(self, ".*database system is ready to accept connections.*", MAX_TRIES, SLEEP_TIME)
+
+        count = 0
+        while count < MAX_TRIES:
+            status, _ = self.exec(f"pg_isready -hlocalhost -p{self.port} -U{self.username}")
+            if status == 0:
+                return
+
+            sleep(SLEEP_TIME)
+            count += 1
+
+        raise RuntimeError("Postgres could not get into a ready state")

postgres/tests/test_postgres.py

@@ -1,20 +1,15 @@
-import sqlalchemy
 from testcontainers.postgres import PostgresContainer
 
 
 def test_docker_run_postgres():
-    postgres_container = PostgresContainer("postgres:9.5")
-    with postgres_container as postgres:
-        engine = sqlalchemy.create_engine(postgres.get_connection_url())
-        with engine.begin() as connection:
-            result = connection.execute(sqlalchemy.text("select version()"))
-            for row in result:
-                assert row[0].lower().startswith("postgresql 9.5")
+    # https://www.postgresql.org/support/versioning/
+    supported_versions = ["11", "12", "13", "14", "latest"]
 
+    for version in supported_versions:
+        postgres_container = PostgresContainer(f"postgres:{version}")
+        with postgres_container as postgres:
+            status, msg = postgres.exec(f"pg_isready -hlocalhost -p{postgres.port} -U{postgres.username}")
+
+            assert msg.decode("utf-8").endswith("accepting connections\n")
+            assert status == 0
 
-def test_docker_run_postgres_with_driver_pg8000():
-    postgres_container = PostgresContainer("postgres:9.5", driver="pg8000")
-    with postgres_container as postgres:
-        engine = sqlalchemy.create_engine(postgres.get_connection_url())
-        with engine.begin() as connection:
-            connection.execute(sqlalchemy.text("select 1=1"))