In this article

Overview

You can use this Snap to read data from various sources (such as SLDB, HTTP, S3, SFTP, HDFS, etc.) and produce a binary data stream at the output.

Important

We plan to introduce additional S3 features exclusively in Amazon S3 Snaps, while Binary Snaps with S3 support will not contain these updates. Therefore, we recommend you to use the Amazon S3 Snap Pack for all your S3 operations within your pipelines. However, Binary Snaps will be retained as is to maintain backward compatibility, but be aware that we will no longer provide S3 support for the Binary Snaps.

Learn more: Migration from Binary Snaps to Amazon S3 Snaps.

Snap Type

The File Reader Snap is a Read type Snap.

Prerequisites

IAM Roles for Amazon EC2

The 'IAM_CREDENTIAL_FOR_S3' feature is used to access S3 files from EC2 Groundplex, without Access-key ID and Secret key in the AWS S3 account in the Snap. The IAM credential stored in the EC2 metadata is used to gain access rights to the S3 buckets. To enable this feature, the following line should be added to global.properties and the jcc (node) restarted:
jcc.jvm_options = -DIAM_CREDENTIAL_FOR_S3=TRUE

Please note this feature is supported in the EC2-type Groundplex only.

For more information on IAM Roles, see http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html

Connect to FTP server:

To connect to the FTP server that needs to reuse the session for data transfer over TLS protocol, add:

-DFTPS_SSL_TLS_PROTOCOL=TLSV1.2 (or) TLSV1.3property as a JVM option under the Global properties of the Node Properties tab:

Support for Ultra Pipelines

Works in Ultra Pipelines.

Limitations

For most file protocols, the Snap behaves the same in both Snaplex and Groundplex. However, the HDFS protocol works only in the Groundplex. The Hadoop cluster must be open to the Groundplex server instance without any authentication.
When reading a file over HTTP, the File Reader Snap displays an error if the number of bytes consumed does not match the Content-Length header value present in the response.
Do not use sldb as a file system or storage. File Assets are intended only for specialized files that a pipeline uses to reference specific data, such as accounts, expressions, or JAR files. Use a Cloud storage provider to store production data. File Assets should not be used as a file source or as a destination in production pipelines. When you configure the File Reader Snap, set the file path to a cloud provider or an external file system.

Known Issues

This Snap fails for SMB file path with the error: unable to create new native thread.
This Snap Pack does not natively support SHA1-based algorithms to connect to SFTP endpoints. With the August 2023 GA release, you can now leverage the properties specified in the Configuration settings for Snaps to add support for ones that are disabled on your Snaplex.
If the Snap encounters a file with the same name as your Project Space, it can result in an error when you attempt to use that file's name within the Mapper Snap. For instance, if your Project Space is named "servicenow/to_snowflake" and the file being read is named "servicenow_to_snowflake_demo.json," you may encounter issues.
Consider using the complete file path instead of just the file name as a workaround.

Snap Views

Type

Format

Number of Views

Examples of Upstream and Downstream Snaps

Description

Input

Document

Min: 0
Max: 1

Upstream Snap is optional. Any Snap with a document output view can be connected upstream.

Input may contain value(s) to evaluate the JavaScript expression in the File property.

Output

Document

Min: 1
Max: 2

File Writer
CSV Parser
JSON Parser
XML Parser

Binary data read from the source specified in the File property with header information about the binary stream.

When reading a file, all the characters in the filename (except dot, hyphen, underscore, space, alphabet, and digit) are replaced with an underscore (_) in the content-disposition column of the output. If you want to get the exact file name in the output column, consider using content-location as the identifier instead of content-disposition.

An example of the output preview on the File property value of "http://www.facebook.com" is as follows:

[ { "": "Preview binary0...", "content-type": "text/html; charset=utf-8", "x-frame-options": "DENY",
 "connection": "keep-alive", "transfer-encoding": "chunked", "date": "Thu, 23 Oct 2014 00:24:40 
GMT", "content-location": "https://www.facebook.com", "pragma": "no-cache", "p3p": "CP=\"Facebook 
does not have a P3P policy. Learn why here: http://fb.me/p3p\"", "cache-control": "private, no-
cache, no-store, must-revalidate", "x-xss-protection": "0", "x-content-type-options": "nosniff", "x-
fb-debug": 
"N6wiHWAvz9kzpPUoM5vTm+yZzCZyiSrHXFXumHQixfMd0Qi+VDm514PkrrmQu2ISuuMTTFtUTqDZgDVG4blPTw==", 
"expires": "Sat, 01 Jan 2000 00:00:00 GMT", "set-cookie": "reg_ext_ref=deleted; expires=Thu, 01-Jan-
1970 00:00:01 GMT; Max-Age=0; path=/; domain=.facebook.com" } ]

Error

Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the Pipeline by choosing one of the following options from the When errors occur list under the Views tab:

Stop Pipeline Execution: Stops the current pipeline execution when the Snap encounters an error.
Discard Error Data and Continue: Ignores the error, discards that record, and continues with the remaining records.
Route Error Data to Error View: Routes the error data to an error view without stopping the Snap execution.

Learn more about Error handling in Pipelines.

Snap Settings

Field Field Type Description

Label*

Default Value: File Reader
Example: File Reader

String

Specify a unique name for the Snap. You can modify this to be more specific, especially if you have more than one of the same Snap in your Pipeline.

File*

Default Value: N/A
Example:

"asset.json" or "sldb:///asset.json"
"shared/asset.json" or "sldb:///shared/asset.json"
s3://my-bucket@bucket.vpce-028b7814794578709-vu0vvauy.s3.us-west-2.vpce.amazonaws.com
s3:///<S3_bucket_name>@s3.<region_name>.amazonaws.com/<path>/<file_name>
For region names and their details, see AWS Regions and Endpoints.
Example: s3:///mybucket@s3.eu-west-1.amazonaws.com/test.json
sftp://ftp.snaplogic.com:22/dir/filename
smb://smb.snaplogic.com:445/test_files/csv/input.csv
$filename (The value of the $filename is obtained from the input document and the document should have an entry with the "filename" key.)
_filename (A key/value pair with "filename" key should be defined as a pipeline parameter.)
file:///D:/testFolder/ (if the Snap is executed in the Windows Groundplex and needs to access D: drive)
wasb:///Snaplogic/testDir/sample.csv (to read 'sample.csv' file in the 'testDir' folder in the 'Snaplogic' container)
gs:///mybucket/csv/test.csv (to read 'test.csv' file in the 'csv/' folder of the 'mybucket' bucket)
adl://storename/folder/filename (to read the file from a location of the storage)

String/Expression

Specify the URL for a regular file that must begin with a file protocol. The supported file protocols are:

http:
https:
s3:
ftp:
ftps:
sftp:
hdfs:
sldb:
smb:
file: (only for use with a Groundplex)
wasb:
wasbs:
gs:
adl:

You can also upload a file from using the Upload icon. You can preview the uploaded file using the previewicon. Learn more about Previewing File.

This Snap supports S3 Virtual Private Cloud (VPC) endpoints. For example:

s3://my-bucket@bucket.vpce-028b7814794578709-vu0vvauy.s3.us-west-2.vpce.amazonaws.com

This Snap supports Oracle Object Storage endpoints when used with pre-authenticated requests. For example:

https://objectstorage.us-sanjose-1.oraclecloud.com/p/123AbcdEFG12345_xyz123/n/MyNamespace/b/snaplogic-academy/o/sample.json

To create a pre-authenticated request, refer to the instructions in the following Oracle article:
Using Pre-Authenticated Requests.

Reading files from Project and Shared Project Spaces

If a Pipeline is created in a project other than the shared project and you want to read the "asset.json" file from the same project, enter "asset.json" or "sldb:///asset.json".
If a Pipeline is created in the shared project and you want to read the "asset.json" file from the shared project, enter "asset.json" or "sldb:///asset.json".
If a Pipeline is created in a project other than the shared project and you want to read the "asset.json" file from the shared project, enter "shared/asset.json" or "sldb:///shared/asset.json".
Ensure the file name, folder name, or the file path does not contain '?' character because it is not fully supported and when present, the Snap might fail.

File value as an Expression

The File value can be a JavaScript expression which is evaluated with values from the input view document and the pipeline parameters. The syntax for file value is: [protocol]://[host][:port]/[path]

$filename (The value of the $filename is obtained from the input document and the document should have an entry with the "filename" key.)
_filename (A key/value pair with "filename" key should be defined as a pipeline parameter.)

The File value should be an absolute path for all protocols except for SLDB. For files in SLDB, the Snap can read only files in the same Project Directory or the Shared Project Directory. It cannot access files from other Projects. Typically, the file names in the Reader Snaps are read from incoming document which might have a structure different from the relative path. For optimal results, we recommend that you build absolute paths to their projects and then add the file name.
Note: When you provide a file path that contains more than five entities (for example, entity1/entity2/entity3/entity4/file1.json) the Snap displays a Lint Warning in your Pipeline.

"://" is a separator between the file protocol and the rest of the URL and the host name and the port number should be between "://" and "/". The hostname and port number are omitted in the SLDB and s3 protocols. If the port number is omitted, a default port for the protocol is used.
The file:/// protocol is supported only on Groundplex. In Cloudplex configurations, use SLDB or other file protocols. When using the file:/// protocol, the file access is done using the permissions of the user assigned or associated with the Snaplex (by default Snapuser). File system access is to be used with caution, and it is the customer's own responsibility to ensure that file system is cleaned up after use.

Prevent URL encoding

Default value: Deselected

Checkbox

When enabled, this will prevent the Snap from automatically URL encoding the file path (including the query string if it exists). Enable this setting to use the file path value as-is.

When disabled, the following are some of the common characters that are automatically encoded by the Snap:

Character name	Character	URL Encoded value
backslash	\	%5C
Pound	#	%23
space		%20
percent	%	%25
Left-angle	<	%3C
Right-angle	>	%3E
Left-angle	[	%5B
Right-square	]	%5D
Right-curly	{	%7B
Right-curly	}	%7D

And these are some of the characters that are not automatically encoded by the Snap:

Character name	Character	URL Encoded value
semi-colon	;	%3B
question mark	?	%3F
forward slash	/	%2F
colon	:	%3A
ampersand	&	%26
equals	=	%3D
plus	+	%2B
dollar	$	%24
comma	,	%2C

Enable staging

Default value: Deselected

Checkbox

If selected, the Snap downloads the source file into a local temporary file. When the download is completed, it streams the data from the temporary file to the output view. This property prevents the Snap from being blocked by slow downstream pipeline. The local disk should have sufficient free space as large as the expected file size.

Some Snaps may take a long time to process large amounts of data. This, in turn, could lead to connection timeouts, causing the pipeline to fail. Selecting this property saves the data on your local disk, enabling you to avoid such timeouts.

Number of retries

Default Value: 0
Example: 3

Integer/Expression

Specify the maximum number of retry attempts that the Snap must make in case there is a network failure, and the Snap is unable to read the target file.

If the value is larger than 0, the Snap first downloads the target file into a temporary local file. If any error occurs during the download, the Snap waits for the time specified in the Retry interval and attempts to download the file again from the beginning. When the download is successful, the Snap streams the data from the temporary file to the downstream Pipeline. All temporary local files are deleted when they are no longer needed.
Ensure that the local drive has sufficient free disk space to store the temporary local file.

Minimum value: 0

Retry interval (seconds)

Default Value: 1
Example: 3

Integer/Expression

Specify the minimum number of seconds for which the Snap must wait before attempting recovery from a network failure.

Minimum value: 1

Advanced properties

Use this field set to define specific settings for polling files. Click

to add a new row for defining an advanced property. This field set contains the following fields:

Properties
Values

Properties

Dropdown list

The URI of the Shared Access Storage (SAS) to be accessed. Supported SAS types are:

Service SAS on container
Service SAS on blob
Account SAS

Values

Default Value: N/A

Example: https://myaccount.blob.core.windows.net/sascontainer/sasblob.txt?sv=2015-04-05&st=2015-04-
29T22%3A18%3A26Z&se=2015-04-30T02%3A23%3A26Z&sr=b&sp=rw&sip=168.1.5.60
-168.1.5.70&spr=https&sig=Z%2FRHIX5Xcg0Mq2rqI3OlWTjEg2tYkboXr1P9ZUXDtkk%3D

String/Expression

Specify the value for the SAS URI.

Ensure that the URI is specified in the format described here.

If the SAS URI value is provided in the Snap settings, then the settings provided in the account (if any account is attached) are ignored.

Snap Execution

Default Value: Execute only
Example: Validate & Execute

Dropdown list

Select one of the three modes in which the Snap executes. Available options are:

Validate & Execute: Performs limited execution of the Snap, and generates a data preview during Pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during Pipeline runtime.
Execute only: Performs full execution of the Snap during Pipeline execution without generating preview data.
Disabled: Disables the Snap and all Snaps that are downstream from it.

As of the Fall 2015 release, only File Reader/Writer Snaps support the Azure Storage protocol (azure:///).
As of the Fall 2017 release, the File Reader Snap shows the progress message during the Pipeline runtime.

Preview File

To preview a file, in the File field, click the Preview icon.

The Preview Type contains the following options:

Hex: Displays the preview data in hexadecimal format.
Text: Displays the preview data in text format.
Render text with whitespace: Renders whitespaces as dots "." and tabs as underscores "_" in the preview data.

Examples

HDFS Example

HDFS

For hdfs:// file access, please use a SnapLogic on-premises Groundplex and make sure that its instance is within the Hadoop cluster and SSH authentication has already been established. You can access HDFS files in the same way as other file protocols in File Reader and File Writer Snaps. There is no need to use any account in the Snap.

HDFS 2.4.0 is supported for the hdfs protocol.

hdfs://<hostname>:<port number>/<path to folder>/<filename>

An example for HDFS is:

hdfs://<hostname>:<port number>/<path to folder>/<filename>

If Cloudera Hadoop Namenode is installed in AWS EC2 and its hostname is "ec2-54-198-212-134.compute-1.amazonaws.com" and its port number is 8020, then you would enter:

hdfs://ec2-54-198-212-134.compute-1.amazonaws.com:8020/user/john/input/sample.csv

SFTP File Read

Example pipeline for an SFTP file read as shown below:

The 'IAM_CREDENTIAL_FOR_S3' feature is to access S3 files from EC2 Groundplex without Access-key ID and Secret key in the AWS S3 account in the Snap. The IAM credential stored in the EC2 metadata is used to gain the access rights to the S3 buckets. To enable this feature, the following line should be added to global.properties and restart the JCC:
jcc.jvm_options = -DIAM_CREDENTIAL_FOR_S3=TRUE
This feature is supported in the EC2-type Groundplex only.

Sample for AWS S3 Support

Troubleshooting

Error Reason Resolution

Response code: 400, unable to import the file <file name>

Request from elastic.snaplogic.com returned an error.

The name of the file that is being read by the Snap cannot be the same as the Project Space name.

Provide the complete path of the file (instead of only the file name) in this format: “/orgname/projectspace/project/filename”

For example: /snaplogic/shared/analytics/ga4.json

Response code: 400, unable to import expression library: <file_ProjectSpace>