Add a script to create metricity db if it doesn't exist

1 files changed, 46 insertions, 0 deletions

diff --git a/create_metricity_db.py b/create_metricity_db.py
new file mode 100644
index 0000000..edec2db
--- /dev/null
+++ b/create_metricity_db.py
@@ -0,0 +1,46 @@
+"""Ensures the metricity db exists before running migrations."""
+import os
+from urllib.parse import SplitResult, urlsplit
+
+import psycopg2
+from psycopg2 import sql
+from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT
+
+
+def parse_db_url(db_url: str) -> SplitResult:
+    """Validate and split the given databse url."""
+    db_url_parts = urlsplit(db_url)
+    if not all((
+        db_url_parts.hostname,
+        db_url_parts.username,
+        db_url_parts.password
+    )):
+        raise ValueError(
+            "The given db_url is not a valid PostgreSQL database URL."
+        )
+    return db_url_parts
+
+
+if __name__ == "__main__":
+    database_parts = parse_db_url(os.environ["DATABASE_URI"])
+
+    conn = psycopg2.connect(
+        host=database_parts.hostname,
+        port=database_parts.port,
+        user=database_parts.username,
+        password=database_parts.password
+    )
+
+    db_name = database_parts.path[1:] or "metricity"
+
+    # Required to create a database in a .execute() call
+    conn.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)
+    with conn.cursor() as cursor:
+        cursor.execute("SELECT 1 FROM pg_catalog.pg_database WHERE datname = %s", (db_name,))
+        exists = cursor.fetchone()
+        if not exists:
+            print("Creating metricity database.")
+            cursor.execute(
+                sql.SQL("CREATE DATABASE {dbname}").format(dbname=sql.Identifier(db_name))
+            )
+    conn.close()