Snowflake

Source Snowflake #

The extracted replicant-cli will be referred to as the $REPLICANT_HOME directory in the proceeding steps.

I. Create Streams #

To create streams for tracking individual table changes for CDC, follow the instructions in Streams.

II. Create Stage Table #

To create stage table as an intermediate buffer of the CDC process, follow the instructions in Stage Tables.

III. Set up Connection Configuration #

  1. From $REPLICANT_HOME, navigate to the sample connection configuration file:

    vi conf/conn/snowflake.yaml
    
  2. The configuration file has two parts:

    • Parameters related to source Snowflake server connection.
    • Parameters related to stage configuration.

    For connecting to target Snowflake server, you can choose between two methods for an authenticated connection:

    For connecting to Snowflake via basic username and password authentication, see the sample below:

    type: SNOWFLAKE
    
    host: SNOWFLAKE_HOSTNAME
    port: PORT_NUMBER 
    warehouse: "WAREHOUSE_NAME"
    
    username: "USERNAME"
    password: "PASSWORD"
    
    max-connections: 20 #Specify the maximum number of connections replicant can open in Snowflake
    max-retries: 10
    retry-wait-duration-ms: 1000
    

    Replace the following:

    • SNOWFLAKE_HOSTNAME: the Snowflake hostname. The hostname is in the format ACCOUNT_NAME.REGION_ID.snowflakecomputing.com or ACCOUNT_NAME.snowflakecomputing.com—for example, replicate_partner.snowflakecomputing.com.
    • PORT_NUMBER: the port number of Snowflake host
    • WAREHOUSE_NAME: the name of the Snowflake warehouse
    • USERNAME: the username to connect to the Snowflake server
    • PASSWORD: the password associated with USERNAME
    Note: Make sure the specified user has CREATE TABLE and CREATE STREAM privileges on the catalogs/schemas from which tables need to be replicated.

    Additional parameters #

    • credential-store: Replicant supports consuming username and password configurations from a credentials store rather than having users specify them in plain text config file. You can use keystores to store your credentials related to your Snowflake server connections.The following parameters are available:

      • type: Type of the keystore. Allowed types are PKCS12, JKS, and JCEKS.
      • path : Location of the key-store.
      • key-prefix: You should create entries in the credential store for your configs using a prefix and specify the prefix here. For example, you can create keystore entries with aliases snowflake1_username and snowflake1_password. You can then specify the prefix here as snowflake1_.
      • password: This field is optional. If you don’t specify the keystore password here, then you must use the UUID from your license file as the keystore password. Remember to keep your license file somewhere safe in order to keep the password secure.
    • stage: By default, Replicant uses Snowflake’s native stage for bulk loading. But it’s also possible to use an external stage like Azure. This section allows you to specify the details Replicant needs to connect to and use a specific stage.

    • type[v21.06.14.1]: The stage type. Allowed stages are NATIVE, S3, and AZURE.

    • root-dir: Specify a directory on stage which can be used to stage bulk-load files. -conn-url[v21.06.14.1]: URL for the stage. For example, if stage is S3, specify bucket name; for AZURE, specify container name.

    • key-id : This config is valid for S3 stage type only. Access Key ID for AWS account hosting s3.

    • account-name[v21.06.14.1] : This config is valid for AZURE type only. Name of the ADLS storage account. -secret-key[v21.06.14.1]: This config is valid for both S3 and AZURE types. For example, Secret Access Key for AWS account hosting s3 or ADLS account.

    • token[v21.06.14.1]: This config is valid for AZURE type only. Indicates the SAS token for Azure storage.

    Use RSA key pair for authentication #

    You can also choose to use Snowflake’s key pair authentication support for enhanced authentication security instead of using basic authentication via username and password.

    To set up key pair authentication using RSA keys, follow the steps below:

    Generate the private key #

    From your command line, execute the following command to generate an encrypted private key:

    openssl genrsa 2048 | openssl pkcs8 -topk8 -inform PEM -v1 PBE-SHA1-RC4-128 -out rsa_key.p8
    

    The command generates a private key in PEM format:

    -----BEGIN ENCRYPTED PRIVATE KEY-----
    MIIFHDBOBgkqhkiG9w0BBQ0wQTApBgkqhkiG9w0BBQwwHAQIK0h8dqI1n5sCAggA
    MAwGCCqGSIb3DQIJBQAwFAYIKoZIhvcNAwcECNDwqMf6Xx1pBIIEyNmf044S+pEQ
    ...
    -----END ENCRYPTED PRIVATE KEY-----
    

    Important: The command above to generate an encrypted key prompts for a passphrase to grant access to the key. We recommend using a passphrase that complies with PCI DSS standards to protect the generated private key. Additionally, we recommend storing the passphrase in a secure location. When using an encrypted key to connect to Snowflake, you will need to input the passphrase during the initial connection. The use of the passphrase is only for protecting the private key; it’s never to sent to Snowflake servers.

    To generate a long and complex passphrase based on PCI DSS standards, follow the steps below:

    • Go to the PCI Security Standards Document Library.
    • For PCI DSS, select the most recent version and your desired language.
    • Complete the form to access the document.
    • Search for Passwords/passphrases must meet the following: and follow the recommendations for password/passphrase requirements, testing, and guidance.

    Generate a public key #

    From the command line, generate the public key by referencing the private key. The following command references the private key contained in a file named rsa_key.p8 created in the previous step:

    openssl rsa -in rsa_key.p8 -pubout -out rsa_key.pub
    

    The command generates a public key in PEM format:

    -----BEGIN PUBLIC KEY-----
    MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAslwTa+Lj5SMI58GiDzWq
    0rwj4FBymfKzHT16RXecnMcx7uI6KsVpqfh9HH0FMb/3C6YEMeGPkaRmKvXYjM5s
    ...
    -----END PUBLIC KEY-----
    

    Store the Private and Public Keys Securely #

    After following the above steps, you should find the private and public key files saved in a local directory of your system. Note down the path to those files. The private key is stored using the PKCS#8 (Public Key Cryptography Standards) format and is encrypted using the passphrase you specified in the first step.

    However, maintain caution in protecting the file from unauthorized access using the file permission mechanism provided by your operating system. It’s your responsibility to secure the file when it’s not being used.

    Assign the public key to a Snowflake user #

    Execute the following command to assign the public key to a Snowflake user.

    alter user jsmith set rsa_public_key='MIIBIjANBgkqh...';
    
    • Only security administrators (i.e. users with the SECURITYADMIN role) or higher can alter a user.
    • Exclude the public key delimiters in the SQL statement.

    Verify the user’s public key fingerprint #

    Execute the following command to verify the user’s public key:

    DESC USER jsmith;
    

    The command output is similar to the following:

    +---------------------+-----------------------------------------------------+---------+----------------------------------------------+
    | property            | value                                               | default | description                                  |
    +---------------------+-----------------------------------------------------+---------+----------------------------------------------+
    | NAME                | JSMITH                                              | null    | Name                                         |
    ...
    ...
    | RSA_PUBLIC_KEY      | MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAslwT... | null    | RSA public key of the user                   |
    | RSA_PUBLIC_KEY_FP   | SHA256:nvnONUsfiuycCLMXIEWG4eTp4FjhVUZQUQbNpbSHXiA= | null    | Fingerprint of user's RSA public key.        |
    | RSA_PUBLIC_KEY_2    | null                                                | null    | Second RSA public key of the user            |
    | RSA_PUBLIC_KEY_2_FP | null                                                | null    | Fingerprint of user's second RSA public key. |
    ...
    +---------------------+-----------------------------------------------------+---------+----------------------------------------------+
    

    Edit the connection configuration file #

    You need to modify Replicant’s connection configuration file for Snowflake and include RSA key information there. Specifically, add the following parameters to the connection configuration file:

    private-key-path: "/PATH_TO_GENERATED_KEY/rsa_key.p8"
    private-key-passphrase: "PRIVATE_KEY_PASSPHRASE"
    

    Replace the following:

    • PATH_TO_GENERATED_KEY: the local directory path to the rsa_key.p8 keyfile
    • PRIVATE_KEY_PASSPHRASE: the private key passphrase you specified in the first step
    If you specify the private-key-path and private-key-passphrase parameters, you don’t need to specify the password parameter in the connection configuration file.

IV. Set up Extractor Configuration #

  1. From $REPLICANT_HOME, navigate to the Applier configuration file:
    vi conf/src/snowflake.yaml
    
  2. Make the necessary changes as follows:
snapshot:
  threads: 32
    #  fetch-size-rows: 5_000

    #  min-job-size-rows: 1_000_000
    #  max-jobs-per-chunk: 32

    #native-extract-options:
    #control-chars:
    #delimiter: ','
    #quote: '"'
    #escape: "\u0000"
    #null-string: "NULL"
  #line-end: "\n"

  _traceDBTasks : true

  per-table-config:
    - catalog: DEMO_DB
      schema: tpch
      tables:
        orders:
#        num-jobs: 2
#        split-hints:
#          row-count-estimate: 15000

realtime:
  threads: 8
  fetch-size-rows: 10000
  _traceDBTasks: true
  #fetch-interval-s: 0
  #create-stream: true
  #create-stage-table: true

For a detailed explanation of configuration parameters in the extractor file, read Extractor Reference.