Elastic Container Instance:Connect an ECI pod to an RDS instance

Background

ApsaraDB RDS is a stable, reliable, and scalable online database service from Alibaba Cloud. Built on the Alibaba Cloud distributed file system and high-performance solid-state drives (SSDs), ApsaraDB RDS supports multiple database engines, such as MySQL, SQL Server, and PostgreSQL. This topic uses an ApsaraDB RDS for MySQL instance as an example. You can select a database engine based on your business requirements. For more information, see Database engines.

Prerequisites

• An ApsaraDB RDS for MySQL instance is created and a database account is configured for the instance. For more information, see Create an ApsaraDB RDS for MySQL instance and Create a database and an account.

• An ACK Serverless cluster is created. For more information, see Create an ACK Serverless cluster.

  Note

  This topic uses an ACK Serverless cluster as an example. If you use a different type of Kubernetes cluster, make sure that a virtual node is deployed in the cluster to connect to ECI.

• The ApsaraDB RDS instance and the Kubernetes cluster can communicate with each other.

  For optimal performance and security, deploy the ApsaraDB RDS instance and the Kubernetes cluster in the same Virtual Private Cloud (VPC). This enables internal network communication. If they are in different VPCs, you must configure access over the public network.

Configure the RDS whitelist and get the endpoint

Configure an application to connect to RDS

This procedure shows how to connect an ACK Serverless cluster to an ApsaraDB RDS instance over an internal network.

1. Log on to the ACK console.

2. On the Cluster page, find your target cluster and click its name to open the cluster details page.

3. Create a ConfigMap to store the ApsaraDB RDS connection information.

   Note

   A ConfigMap decouples environment configuration from the container image. This simplifies application configuration updates.

   1. In the left-side navigation pane, choose Configuration > ConfigMaps.

   2. Click Create.

   3. Enter the ConfigMap details and click OK.

      Set the name to rds-config and add the following key-value pairs:

      Parameter	Example	Description
      host	rm-2zem97a62s9******.mysql.rds.aliyuncs.com	The database endpoint. Available on the Database Connection page of your ApsaraDB RDS instance.
      port	3306	The database port. Available on the Database Connection page of your ApsaraDB RDS instance.
      database	test-db	The database name. Available on the Databases page of your ApsaraDB RDS instance.

4. Create a Secret to store the database username and password.

   Note

   Using a Secret is a best practice for securely managing sensitive information, such as database credentials, for your application.

   1. In the left-side navigation pane, choose Configuration > Secrets.

   2. Click Create.

   3. Enter the Secret details and click OK.

      Set the name to rds-secret and add the following key-value pairs:

      Parameter	Example	Description
      username	test	The database username. Available on the Accounts page of your ApsaraDB RDS instance.
      password	pwd******	The database password. If you forget the password, reset it on the Accounts page of your ApsaraDB RDS instance.

5. Create an ECI pod to test the connection.

   1. In the left-side navigation pane, choose Workloads > Pods.

   2. Click Create from YAML.

   3. Enter the YAML configuration and click Create.

      ApsaraDB RDS is fully compatible with native database services. You can use any standard database client to connect to your ApsaraDB RDS instance. The following YAML file is an example:

      Note

      To use this example, you must first create a table named username with a column named user in your ApsaraDB RDS instance.

      The following YAML configuration uses environment variables to provide the database connection details: endpoint, port, name, username, and password. The container image includes a Python script that connects to the database and inserts data.

      apiVersion: v1
      kind: Pod
      metadata:
        labels:
          name: rds-test
        name: rds-test
      spec:
        containers:
        - name: test-rds
          image: registry.cn-hangzhou.aliyuncs.com/eci_open/sqlclient:1.0.1  # A container image that contains a Python script to connect to the database.
          imagePullPolicy: IfNotPresent
          command: ["/bin/bash","-c","python3 /testapp/mysqlclient.py"]
          env:
          - name: MYSQL_HOST 
            valueFrom:
              configMapKeyRef:
                name: rds-config  # The name of the ConfigMap.
                key: host  # The key in the ConfigMap.
          - name: MYSQL_PORT
            valueFrom:
              configMapKeyRef:
                name: rds-config # The name of the ConfigMap.
                key: port # The key in the ConfigMap.
          - name: MYSQL_DB
            valueFrom:
              configMapKeyRef:
                name: rds-config  # The name of the ConfigMap.
                key: database # The key in the ConfigMap.
          - name: MYSQL_USERNAME
            valueFrom:
              secretKeyRef:
                name: rds-secret # The name of the Secret.
                key: username  # The key in the Secret.
          - name: MYSQL_PWD
            valueFrom:
              secretKeyRef:
                name: rds-secret # The name of the Secret.
                key: password # The key in the Secret.
        restartPolicy: Never

      The image in the preceding example contains a Python script (mysqlclient.py) that inserts a row into the user column of the username table. The script is as follows:

      import pymysql
      import os
      import time
      config = {
          'host': str(os.getenv('MYSQL_HOST')),
          'port': int(os.getenv('MYSQL_PORT')),
          'user': str(os.getenv('MYSQL_USERNAME')),
          'password': str(os.getenv('MYSQL_PWD')),
          'database': str(os.getenv('MYSQL_DB')),
      }
      def mysqlClient():
          print("Connecting to the database...")
          db = pymysql.connect(**config)
          try:
              cursor = db.cursor()
              cursor.execute("INSERT INTO username(user) VALUES('Mrs')")
              cursor.close()
              db.commit()
              cursor = db.cursor()
              cursor.execute("SELECT user FROM username")
              result = cursor.fetchall()
              cursor.close()
              if result != None:
                  print(result)
                  time.sleep(99999)
          except Exception as e:
              print('System Error: ', e)
          finally:
              db.close()
      if __name__ == '__main__':
          mysqlClient()

6. Log on to the database and verify the result.

   1. Log on to the ApsaraDB RDS console.

   2. In the left-side navigation pane, click Instances. In the top navigation bar, select the region where your instance is located, and then click the instance ID.

   3. In the left-side navigation pane, click Databases.

   4. Find the target database and click SQL Query in the Actions column.

   5. In the dialog box that appears, enter the database username and password, and then click Log In.

   6. Run an SQL command to check the result.

      Run the SELECT * FROM `username` command. The output shows a new row in the user column of the username table.

FAQ

Common reasons for database connection failures include:

• Different network types

• Different VPCs

• Domain name resolution failure or error

• Different regions

• Incorrect IP address whitelist configuration

• Whitelist not configured for a read-only instance

• Incorrect use of internal or public endpoints

• Connection limit reached

• Incorrect username or password

• Unable to resolve the endpoint

Troubleshoot the issue based on your network environment (internal network or public network). For more information, see Troubleshoot ApsaraDB RDS connection failures.