Help Center/ Relational Database Service/ Getting Started/ Getting Started with RDS for PostgreSQL/ Buying an RDS for PostgreSQL Instance and Connecting to It Using a PostgreSQL Client
Updated on 2025-11-11 GMT+08:00
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Buying an RDS for PostgreSQL Instance and Connecting to It Using a PostgreSQL Client

You can connect to your DB instance using a Linux ECS with a PostgreSQL client installed over a private network.

You can use the PostgreSQL client to connect to your DB instance over a Secure Sockets Layer (SSL) connection. SSL encrypts connections to your DB instance, making in-transit data more secure.

SSL is enabled by default when you create an RDS for PostgreSQL DB instance and cannot be disabled after the instance is created.

Operation Process

Process

Description

Step 1: Buy an RDS for PostgreSQL DB Instance

Select required basic settings and additional options and buy an RDS for PostgreSQL DB instance.

Step 2: Buy an ECS

If you want to use a PostgreSQL client to connect to a DB instance, you need to prepare a server, install a PostgreSQL client on the server, and run the connection command.

Purchase a Linux ECS that is in the same region and VPC as your DB instance.

Step 3: Test Connectivity and Install a PostgreSQL Client

Test the network connectivity between the ECS and the floating IP address and port of the DB instance, and install a PostgreSQL client on the ECS.

Step 4: Connect to the DB Instance Using a CLI (SSL Connection)

Use a command-line interface (CLI) to connect to the DB instance through the floating IP address and port.

Step 1: Buy an RDS for PostgreSQL DB Instance

Select required basic settings and additional options and buy an RDS for PostgreSQL DB instance. For details, see section "Buying an RDS for PostgreSQL DB Instance" in Relational Database Service User Guide.

Step 2: Buy an ECS

  1. Check whether there is a Linux ECS that meets the requirements.

    RDS for PostgreSQL supports the following client installation methods:

    • Download the PostgreSQL client installation package. This method is recommended for PostgreSQL 15 and earlier versions. It has requirements on ECS images. For details, see the official PostgreSQL documentation.
    • Download the source code. This method has no requirements on PostgreSQL versions or ECS images.
    • If yes, go to 2.
    • If no, purchase an ECS and select Linux (for example, CentOS 7) as its OS.

      To download a PostgreSQL client to the ECS, bind an EIP to the ECS. The ECS must be in the same region, VPC, and security group as the RDS for PostgreSQL DB instance for mutual communications.

  2. Check whether the ECS and RDS for PostgreSQL instance are in the same region and VPC.

    • If they are not in the same region, purchase another ECS. The ECS and DB instance in different regions cannot communicate with each other. To reduce network latency, deploy your DB instance in the region nearest to your workloads.

Step 3: Test Connectivity and Install a PostgreSQL Client

  1. Log in to the ECS. For details, see "Login Using VNC" in the Elastic Cloud Server User Guide.
  2. On the Instances page of the RDS console, click the DB instance name to go to the Overview page.
  3. Choose Connectivity & Security from the navigation pane. In the Connection Information area, obtain the floating IP address and database port of the DB instance.
  4. On the ECS, check whether the floating IP address and database port of the DB instance can be connected. 
    curl -kv 192.168.0.7:5432
    • If yes, network connectivity is normal.
    • If no, check the security group rules.
      • If in the security group of the ECS, there is no outbound rule with Destination set to 0.0.0.0/0 and Protocol & Port set to All, add an outbound rule for the floating IP address and port of the DB instance.
      • If in the security group of the DB instance, there is no inbound rule allowing the access from the private IP address and port of the ECS, add an inbound rule for the private IP address and port of the ECS.
  5. Install a PostgreSQL client.

    The PostgreSQL community provides client installation methods for different OSs. You can download and install a client using the installation tool of the OS. This installation method is simple but can be used only for the OSs supported by the PostgreSQL community.

    In this example, CentOS 7 is used. Use the default installation tool of the OS to install a client (PostgreSQL 15 or earlier).

    Figure 1 Obtaining the installation tool

    Run the installation commands:

    sudo yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
sudo yum install -y postgresql15-server

    Check whether the installation is successful.

    psql -V
    Figure 2 Successful installation
  1. Log in to the ECS. For details, see "Login Using VNC" in the Elastic Cloud Server User Guide.
  2. On the Instances page of the RDS console, click the DB instance name to go to the Overview page.
  3. Choose Connectivity & Security from the navigation pane. In the Connection Information area, obtain the floating IP address and database port of the DB instance.
  4. On the ECS, check whether the floating IP address and database port of the DB instance can be connected. 
    curl -kv 192.168.0.7:5432
    • If yes, network connectivity is normal.
    • If no, check the security group rules.
      • If in the security group of the ECS, there is no outbound rule with Destination set to 0.0.0.0/0 and Protocol & Port set to All, add an outbound rule for the floating IP address and port of the DB instance.
      • If in the security group of the DB instance, there is no inbound rule allowing the access from the private IP address and port of the ECS, add an inbound rule for the private IP address and port of the ECS.
  5. Install a PostgreSQL client.

    Installation from source code: This installation method has no restrictions on RDS for PostgreSQL instance versions and ECS OS types.

    The following uses an ECS using the Huawei Cloud EulerOS 2.0 image as an example to describe how to install a PostgreSQL 16.4 client.

    Figure 3 Checking the ECS image
    1. To use SSL, download OpenSSL to the ECS in advance. 
      sudo yum install -y openssl-devel
    2. Obtain the code download link, run wget to download the installation package to the ECS, or download the installation package to the local PC and then upload it to the ECS. 
      wget https://ftp.postgresql.org/pub/source/v16.4/postgresql-16.4.tar.gz
    3. Decompress the installation package. 
      tar xf postgresql-16.4.tar.gz
    4. Compile the source code and then install the client. 
      cd postgresql-16.4
./configure --without-icu --without-readline --without-zlib --with-openssl
make -j 8 && make install

      If --prefix is not specified, the default path is /usr/local/pgsql. The client can be installed in the simplest way.

      Figure 4 Compilation and installation
    5. Add the following code to the /etc/profile file to configure environment variables: 
      export PATH=/usr/local/pgsql/bin:$PATH
export LD_LIBRARY_PATH=/usr/local/pgsql/lib:$LD_LIBRARY_PATH
source /etc/profile
    6. Test whether the psql is available. 
      psql -V
      Figure 5 Testing psql

Step 4: Connect to the DB Instance Using a CLI (SSL Connection)

  1. On the Instances page of the RDS console, click the DB instance name to go to the Overview page.
  2. In the navigation pane, choose Connectivity & Security.
  3. In the Connection Information area, click next to the SSL field to download Certificate Download.zip, and extract the root certificate ca.pem and bundle ca-bundle.pem from the package.
  4. Upload ca.pem to the ECS.
  5. Run the following command on the ECS to connect to the DB instance: 
    psql --no-readline -h <host> -p <port> "dbname=<database> user=<user> sslmode=verify-ca sslrootcert=<ca-file-directory>"

    Example:

    psql --no-readline -h 192.168.0.7 -p 5432 "dbname=postgres user=root sslmode=verify-ca sslrootcert=/root/ca.pem"
    Table 1 Parameter description

    Parameter

    Example Value

    Description

    <host>

    192.168.0.7

    Floating IP address obtained in 3.

    <port>

    5432

    Database port obtained in 3. The default value is 5432.

    <database>

    postgres

    Name of the database to be connected. The default database name is postgres.

    <user>

    root

    Administrator account root.

    <ca-file-directory>

    /root/ca.pem

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

    sslmode

    verify-ca

    SSL connection mode. Set it to verify-ca to use a CA to check whether the service is trusted.
  6. Enter the password of the database account as prompted. 
    Password:
    If the following information is displayed, the connection is successful. 
    SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off)
Parent Topic: Getting Started with RDS for PostgreSQL