for dev purpose, ability to use dockerized pg instance running

ippisite/ippisite/db_finder.py

+import os
+import subprocess
+
+
+def get_db_ip():
+    result = subprocess.run(
+        [
+            "docker",
+            "ps",
+            "-f",
+            "name=%s" % get_guessed_container_name(),
+            "-q",
+        ],
+        stdout=subprocess.PIPE,
+    )
+    ids = result.stdout.decode("utf-8").strip().split("\n")
+    if len(ids) > 1:
+        raise Exception("Can't find the DB, too much match")
+    if len(ids) == 0 or len(ids[0]) == 0:
+        result = subprocess.run(
+            [
+                "docker",
+                "ps",
+                "-f",
+                "name=_db",
+                "-q",
+            ],
+            stdout=subprocess.PIPE,
+        )
+        ids = result.stdout.decode("utf-8").strip().split("\n")
+        if len(ids) > 1:
+            raise Exception(
+                "Can't find the DB, couldn't guess container name (tried '%s'), "
+                "and too much match with '_db'" % get_guessed_container_name()
+            )
+        if len(ids) == 0 or len(ids[0]) == 0:
+            raise Exception("Can't find the DB")
+    result = subprocess.run(
+        [
+            "docker",
+            "inspect",
+            "-f",
+            "'{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}'",
+            ids[0],
+        ],
+        stdout=subprocess.PIPE,
+    )
+    return result.stdout.decode("utf-8").strip().replace("'", "")
+
+
+def get_guessed_container_name():
+    return (
+        str(os.path.dirname(__file__).split(os.path.sep)[-2]).lower().replace("-", "")
+        + "_db"
+    )
+
+
+if __name__ == "__main__":
+    print(get_db_ip())

ippisite/ippisite/settings.py

@@ -17,6 +17,8 @@ from decouple import config
 from django.utils.translation import gettext_lazy
 from socket import gethostname, gethostbyname
 
+from ippisite import db_finder
+
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 PERSISTENT_DIR = os.path.join(BASE_DIR, 'persistent')
 
@@ -122,13 +124,16 @@ if config("USE_SQLITE_AS_DB", default="False").upper() == "TRUE":
         }
     }
 else:
+    POSTGRES_HOST = config("POSTGRES_HOST", '')
+    if not POSTGRES_HOST:
+        POSTGRES_HOST = db_finder.get_db_ip()
     DATABASES = {
         "default": {
             "ENGINE": "django.db.backends.postgresql",
             "NAME": config("POSTGRES_DB"),
             "USER": config("POSTGRES_USER"),
             "PASSWORD": config("POSTGRES_PASSWORD"),
-            "HOST": config("POSTGRES_HOST"),
+            "HOST": POSTGRES_HOST,
             "PORT": 5432,
         }
     }