Connecting to a DB Instance Through psql

You can use the PostgreSQL client psql to connect to a DB instance through a non-SSL connection or an SSL connection. The SSL connection is encrypted and therefore more secure.

Prerequisites

  1. You have logged in to the ECS.
    • To connect to a DB instance through an ECS, make sure that:
      • The ECS and DB instance must be in the same VPC.
      • The ECS must be allowed by the security group to access RDS DB instances.
        • If the security group with which the target DB instance is associated is the default security group, you do not need to configure security group rules.
        • If the security group with which the target DB instance is associated is not the default security group, check whether the security group rules allow the ECS to connect to the DB instance. For details, see Configuring Security Group Rules.

          If the security group rules allow the access from the ECS, the ECS can connect to the DB instance.

          If the security group rules do not allow the access from the ECS, you need to add a security group rule. The ECS must be allowed by the security group to access DB instances.

  2. You have installed a database client to connect to DB instances.

    For details, see How Can I Install the PostgreSQL Client?

Non-SSL Connection

  1. Log in to the ECS or the device that can access RDS.
  2. Run the following command to connect to the DB instance:

    psql --no-readline -U <user> -h <host> -p <port> -d <datastore> -W

    Table 1 Parameter description

    Parameter

    Description

    <user>

    Indicates the username of the RDS database account. The default administrator is root.

    <host>

    Indicates the IP address of the primary DB instance. To obtain this parameter, go to the Basic Information page of the DB instance. If the DB instance is accessed through the ECS, the IP address can be found in the Floating IP Address field in the Connection Information area.

    <port>

    Indicates the database port in use. The default value is 5432. To obtain this parameter, go to the Basic Information page of the DB instance. The port number can be found in the Database Port field in the Connection Information area.

    <datastore>

    Indicates the name of the database (the default database name is postgres).

    The parameter -W indicates that a password must be entered for the connection. After running this command, you will be prompted to enter a password.

    Example:

    Run the following command as user root to connect to a DB instance:

    psql --no-readline -U root -h 192.168.0.44 -p 5432 -d postgres -W

SSL Connection

  1. Log in to the management console.
  2. Click in the upper left corner and select a region and a project.
  3. Click Service List. Under Database, click Relational Database Service. The RDS console is displayed.
  4. On the Instances page, click the target DB instance. In the DB Information area on the Basic Information page, click in the SSL field to download the root certificate or certificate bundle.
  5. Upload the root certificate to the ECS or save it to the device to be connected to the DB instance.

    For details about how to import the root certificate to the Linux OS on the ECS, see How Can I Import the Root Certificate to a Windows or Linux OS?

  6. Connect to an RDS DB instance. The Linux OS is used as an example.

    psql --no-readline -h <host> -p <port> "dbname=<database> user=<user> sslmode=verify-ca sslrootcert=<ca-file-directory>"

    Table 2 Parameter description

    Parameter

    Description

    <host>

    IP address of the primary DB instance. To obtain this parameter, go to the Basic Information page of the DB instance. If the DB instance is accessed through the ECS, the IP address can be found in the Floating IP Address field in the Connection Information area.

    <port>

    Database port in use. The default value is 5432. To obtain this parameter, go to the Basic Information page of the DB instance. The port number can be found in the Database Port field in the Connection Information area.

    <database>

    Name of the database (the default database name is postgres).

    <user>

    Username of the RDS database account. The default administrator is root.

    <ca-file-directory>

    Directory of the CA certificate for the SSL connection. The certificate should be stored in the directory where the command is executed.

    sslmode

    SSL connection mode. Set it to verify-ca to use a CA to check whether the service is trusted.

    Enter the password of the database account if the following information is displayed:

    Password:

    For example, to connect to a DB instance through an SSL connection as user root, run the following command:

    psql --no-readline -h 192.168.0.44 -p 5432 "dbname=postgres user=root sslmode=verify-ca sslrootcert=/root/ca.pem"

    Password:

  7. The SSL connection is established if information similar to the following is displayed after you log in to the database:

    SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off)

Parent topic: Connecting to a PostgreSQL DB Instance Through a Private Network