Add Avro schema generator Python script

The script is the Python version of the cdc_schema.go application.

server/modules/protocol/examples/cdc_schema.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2016 MariaDB Corporation Ab
+#
+# Use of this software is governed by the Business Source License included
+# in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+#
+# Change Date: 2019-07-01
+#
+# On the date above, in accordance with the Business Source License, use
+# of this software will be governed by version 2 or later of the General
+# Public License.
+
+#
+# This program requires the MySQL Connector/Python to work
+#
+
+import mysql.connector as mysql
+import json
+import sys
+import argparse
+
+parser = argparse.ArgumentParser(description = "CDC Schema Generator", conflict_handler="resolve", epilog="""This program generates CDC schema files for a specific table or all the tables in a database. The
+schema files need to be generated if the binary log files do not contain the
+CREATE TABLE events that define the table layout.""")
+parser.add_argument("-h", "--host", dest="host", help="Network address where the connection is made", default="localhost")
+parser.add_argument("-P", "--port", dest="port", help="Port where the connection is made", default="3306")
+parser.add_argument("-u", "--user", dest="user", help="Username used when connecting", default="")
+parser.add_argument("-p", "--password", dest="password", help="Password used when connecting", default="")
+parser.add_argument("DATABASE", help="Generate Avro schemas for this database")
+
+opts = parser.parse_args(sys.argv[1:])
+
+def parse_field(row):
+    res = dict()
+    name = row[1].lower().split('(')[0]
+
+    if name in ("date", "datetime", "time", "timestamp", "year", "tinytext", "text",
+	        "mediumtext", "longtext", "char", "varchar", "enum", "set"):
+        res["type"] = "string"
+    elif name in ("tinyblob", "blob", "mediumblob", "longblob", "binary", "varbinary"):
+        res["type"] = "bytes"
+    elif name in ("int", "smallint", "mediumint", "integer", "tinyint", "short", "bit"):
+        res["type"] = "int"
+    elif name in ("float"):
+        res["type"] = "float"
+    elif name in ("double", "decimal"):
+        res["type"] = "double"
+    elif name in ("null"):
+        res["type"] = "null"
+    elif name in ("long", "bigint"):
+        res["type"] = "long"
+    else:
+        res["type"] = "string"
+
+
+    res["name"] = row[0].lower()
+
+    return res
+
+try:
+    conn = mysql.connect(user=opts.user, password=opts.password, host=opts.host, port=opts.port)
+    cursor = conn.cursor()
+    cursor.execute("SHOW TABLES FROM {}".format(opts.DATABASE))
+
+    tables = []
+    for res in cursor:
+        tables.append(res[0])
+
+
+    for t in tables:
+        schema = dict(namespace="MaxScaleChangeDataSchema.avro", type="record", name="ChangeRecord", fields=[])
+        cursor.execute("DESCRIBE {}.{}".format(opts.DATABASE, t))
+
+        for res in cursor:
+            schema["fields"].append(parse_field(res))
+
+        dest = open("{}.{}.000001.avsc".format(opts.DATABASE, t), 'w')
+        dest.write(json.dumps(schema))
+        dest.close()
+
+    cursor.close()
+    conn.close()
+
+except Exception as e:
+    print(e)
+    exit(1)
+