04 ClickHouse Setup

When you run ClickHouse manually with clickhouse server without explicitly specifying --config-file, it auto-generates a temporary config in the preprocessed_configs/ directory, and that config:

• Ignores your /etc/clickhouse-server/config.xml
• Overrides any user/password definitions
• Makes it appear as if config changes don’t work

To run ClickHouse manually and set a password for the default user from the beginning — without relying on the default autogenerated config.

Create a custom temporary config file

If you're running ClickHouse from a custom directory or testing, do this:

1. Create a config file my-config.xml in the current directory:

<clickhouse>
    <listen_host>::</listen_host>
    <logger>
        <level>trace</level>
        <console>true</console>
    </logger>

    <http_port>8123</http_port>
    <tcp_port>9000</tcp_port>
    <mysql_port>9004</mysql_port>

    <path>./</path>

    <mlock_executable>true</mlock_executable>

    <users>
        <default>
	    <password>password</password>

            <networks>
                <ip>::/0</ip>
            </networks>

            <profile>default</profile>
            <quota>default</quota>

            <access_management>1</access_management>
            <named_collection_control>1</named_collection_control>
        </default>
    </users>

    <profiles>
        <default/>
    </profiles>

    <quotas>
        <default/>
    </quotas>
</clickhouse>

2. Start ClickHouse with it:

clickhouse server --config-file=./my-config.xml

tip

• The file in preprocessed_configs/ is a cache — do not edit it. Always change the original XML used by --config-file.
• If you omit --config-file, ClickHouse uses embedded defaults with no password required.
• If you’re testing, always provide an explicit config path to ensure reproducibility.

Verify Configuration Works

you’ll typically use a Python client like clickhouse-connect.

pip install clickhouse-connect

import clickhouse_connect

# Example parameters
host = "localhost"
port = 8123
user = "default"
password = "your_password"  # Empty by default
dbname = "default"

client = clickhouse_connect.get_client(
    host=host,
    port=port,
    username=user,
    password=password,
    database=dbname
)

# Run a test query
result = client.query("SELECT now()")
print(result.result_rows)

tip

• clickhouse-connect uses HTTP protocol (port 8123).
• clickhouse-driver uses the native TCP protocol (port 9000).
• By default, ClickHouse does not require a password for the default user unless you've changed the config.