URL File Dialog

Local Files
Workspace View
Clover Server
Hadoop HDFS
Remote Files
Filtering Files and Tips

The URL File Dialog serves to navigate through the file system and select input or output files.

In many components, you are asked to specify the URL of some files. These files can serve to locate the sources of data that should be read, the sources to which data should be written or the files that must be used to transform data flowing through a component and some other file URL. To specify the URL of such a file, you can use the URL File Dialog.

The URL File Dialog has several tabs on it.

URL File Dialog

Figure 25.1. URL File Dialog

Local Files

The Local files tab serves to locate files on a local file system. The combo contains local file system places and parameters. It can be used to specify both CloverETL projects and any other local files.

URL File Dialog - Local files

Figure 25.2. URL File Dialog - Local files


Best practice is to specify the path to files with Workspace view instead of Local view. Workspace view with help of parameters provides you with better portability of your graphs.

Workspace View

Workspace view tab serves to locate files in a workspace of a local CloverETL project.

URL File Dialog - Workspace view

Figure 25.3. URL File Dialog - Workspace view

Clover Server

Clover Server serves to locate files of all opened CloverETL Server projects. Available only for CloverETL Server projects.

URL File Dialog - Clover Server

Figure 25.4. URL File Dialog - Clover Server

Hadoop HDFS

Hadoop HDFS tab serves to locate files on Hadoop Distributed File System.

URL File Dialog - Hadoop HDFS

Figure 25.5. URL File Dialog - Hadoop HDFS

You need a working Hadoop Connection to choose the particular files.

Remote Files

The Remote files tab serves to locate files on a remote computer or on the Internet. You can specify properties of connection, proxy settings, and HTTP properties.

You can type the URL directly in the format described in Supported File URL Formats for Readers or Supported File URL Formats for Writers, or you can specify it with a help of Edit URL Dialog. The Edit URL Dialog is accessible under the globe icon.

Edit URL Dialog

Figure 25.6. Edit URL Dialog

Edit URL Dialog

Edit URL Dialog lets you specify connection to a remote server in pleasant way. Choose the protocol, specify a host name, port, credentials, and path.

The dialog lets you specify the connection using the following protocols:

  • HTTP


  • FTP

  • SFTP - FTP over SSH

  • Amazon S3

  • WebDav

  • WebDav over SSL

  • Windows Share - SMB1/CIFS

  • Windows Share - SMB 2.x, SMB 3.x

Click Save to save the connection settings. Click OK to use it.

Edit URL Dialog

Figure 25.7. Edit URL Dialog

The Load button serves to load a session from the list for subsequent editing.

The Delete button serves to delete the session from the list.

HTTP(S), (S)FTP, WebDav, and SMB

If the protocol is HTTP, HTTPS, FTP, SFTP - FTP over SSH, WebDav, WebDav over SSL, Windows Share - SMB1/CIFS or Windows Share - SMB 2.x or 3.x, the dialog allows you to specify the host name, port, username, password, and path on the server. It allows you to connect anonymously, as well.

SFTP Certificate in CloverETL

If you are reading from or writing into remote files and are connected via an SFTP protocol using a certificate-based authorization, you should:

  • Create a directory named ssh-keys in your project;

  • Put the private key files into this directory and choose a suitable filename with the .key suffix.

    Listed in order from the highest to lowest priority when resolving, the private key file can have the following names:

    1. username@hostname.key

    2. hostname.key

    3. *.key (the files are resolved in alphabetical order).


If you want to explicitly select a certificate for a specific location, the best way is to use the name with the highest priority, i.e. username@hostname.key. In such a case, if the connection succeeds, other keys are ignored.

Figure below shows the format of the OpenSSH private key generated by ssh-keygen.

Example of Generated OpenSSH Private Key

Figure 25.8. Example of Generated OpenSSH Private Key

URL Syntax for FTP Proxy

CloverETL is able to connect to FTP proxy using the following URL syntax:



Your login on the FTP server.
Your login on the proxy server.
The hostname of the FTP server.
Your FTP password.
Your proxy password.
The hostname of the proxy server.

Amazon S3

In the case of the Amazon S3 protocol, the dialog allows you to fill in access Key, secret key, bucket, and path. For better performance, you should fill in the corresponding region.

Edit URL Dialog - Amazon S3

Figure 25.9. Edit URL Dialog - Amazon S3

Having the connection specified, you can choose the particular file(s).

Amazon S3 URL

It is recommended to connect to S3 via endpoint-specific S3 URL: s3://s3.eu-central-1.amazonaws.com/bucket.name/. The end-point in URL should be the end-point corresponding to the bucket.

  • The URL with a specific endpoint has a much better performance than the generic one (s3://s3.amazonaws.com/bucket.name/), but you can only access the buckets of the specific region.

  • The endpoint affects the signature version that will be used. If you connect to the generic one, the signature version may not match the endpoint being used. Therefore the signature is sent twice and you can see an error message in the error log:

    DEBUG [main] - Received error response: com.amazonaws.services.s3.model.AmazonS3Exception: The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256. (Service: null; Status Code: 400; Error Code: InvalidRequest; Request ID: 2D7C4933BD5ED2F8), S3 Extended Request ID: 9wmejqgrZ0jRpgqvw43RXUBZOzm9rnd5/wVN19kSe0dHAF/k5rxq34jvRhy8bHd5JnqBcQTBwkM=
    WARN [main] - Attempting to re-send the request to cloveretl.example.test.s3.eu-central-1.amazonaws.com with AWS V4 authentication. To avoid this warning in the future, please use region-specific endpoint to access buckets located in regions that require V4 signing.

For list of regions and endpoints, see AWS Regions and Endpoints (Amazon S3).

When the S3 URL does not contain Secret Key + Access Key (e.g. s3://s3.eu-central-1.amazonaws.com/bucket.name/path), CloverETL automatically searches for credentials in the following sources (in this order):

  1. Environment Variables


      Recommended since they are recognized by all the AWS SDKs and CLI except for .NET


      only recognized by Java SDK

  2. Java System Properties - aws.accessKeyId and aws.secretKey

  3. Credential profiles file at the default location (~/.aws/credentials)

    shared by all AWS SDKs and the AWS CLI

  4. Credentials delivered through the Amazon EC2 container service

    the AWS_CONTAINER_CREDENTIALS_RELATIVE_URI environment variable must be set and the security manager must have permission to access the variable

  5. Instance profile credentials delivered through the Amazon EC2 metadata service

For detailed information, see the official AWS documentation.


These sources of credentials may be used for graph development in a local project; for example, set aws.accessKeyId and aws.secretKey Java system properties (for ETL Runtime) and add them to CloverETLDesigner.ini (for File URL dialog) so that graphs work in local projects when using S3 URLs without credentials.

URL File Dialog - Remote files

Figure 25.10. URL File Dialog - Remote files


Serves to specify fields and processing type for port reading or writing. Opens only in components that allow such data source or target.

URL File Dialog - Input Port

Figure 25.11. URL File Dialog - Input Port

URL File Dialog - Output Port

Figure 25.12. URL File Dialog - Output Port

See also: Input Port Reading or Output Port Writing


Dictionary tab serves to specify dictionary key value and processing type for dictionary reading or writing. Opens only in components that allow such data source or target.

URL File Dialog - Dictionary

Figure 25.13. URL File Dialog - Dictionary

See also: Using a Dictionary in Graphs

Filtering Files and Tips

If you use File URL Dialog configured to display only some files according to the extension, you can see the File Extension below File URL.

Configured URL File Dialog

Figure 25.14. Configured URL File Dialog


To ensure graph portability, forward slashes are used for defining the path in URLs (even on Microsoft Windows).


The New Directory action is available at the toolbar of Workspace View and the Local Files tab. F7 key can be used as a shortcut for the action. Newly created directory is selected at the dialog and its name can be edited in-line. Press F2 to rename the directory and DEL to delete it.

More detailed information of URLs for each of the tabs described above is provided in sections