Essencium Backend File Storage Module

To be used together with essencium-backend (version >=2.4.5).

This module provides an abstraction layer to store files needed for your application. The actual persistence location and implementation is independent of the handling of files. This is achieved by providing various storage provider implementations that can be used independently of another.

It is possible to store a file with multiple storage providers to provide redundancy and to access these even if not all used providers are available at the time of requesting a file.

Configuration

Development

In order to integrate the file-storage-module into your own application, a strategic decision must be made at the beginning. There are several methods available to generate the primary key of an entry (ID). By the integration of the specific components one determines which strategy is followed.

Example using the sequence strategy:

@SpringBootApplication(
    scanBasePackages = {
      "de.frachtwerk.my.application",
      "de.frachtwerk.essencium.backend",
      "de.frachtwerk.essencium.storage.generic",
      "de.frachtwerk.essencium.storage.impl.sequence"
    })
@EntityScan(
    basePackages = {
      "de.frachtwerk.my.application",
      "de.frachtwerk.essencium.backend",
      "de.frachtwerk.essencium.storage.generic",
      "de.frachtwerk.essencium.storage.impl.sequence"
    })
@ConfigurationPropertiesScan(
    basePackages = {
      "de.frachtwerk.my.application",
      "de.frachtwerk.essencium.backend",
      "de.frachtwerk.essencium.storage.generic",
      "de.frachtwerk.essencium.storage.impl.sequence",
    })
@EnableJpaRepositories(
    basePackages = {
      "de.frachtwerk.my.application",
      "de.frachtwerk.essencium.backend",
      "de.frachtwerk.essencium.storage.generic",
      "de.frachtwerk.essencium.storage.impl.sequence"
    })
public class SpringBootApp {
  public static void main(String[] args) {
    SpringApplication.run(SpringBootApp.class, args);
  }
}

Note that when linking custom entities to files, do not specify an abstract File class, but the specific implementation of the File class (SequenceFile or IdentityFile).

Environment

The module is configured by using the application.yaml config file of your essencium application. The used prefix is file.storage

usedProviders

• Type: String[]
• Required: yes

Specifies the providers that should be used to store files. Note: This does not activate the specified providers.

local

Config parameters for the local provider.

parameter	type	default	required	comment
active	boolean	false		Setting active to true tells the spring application to include components needed for the local storage provider in its component and entity scan. A file stored with the local provider cannot be loaded if active is not set to true.
keepFileName	boolean	false		Whether to use the provided original file when storing the file on the file system. When set to false randomized uuid's are used as file names.
useTempFiles	boolean	false		Whether to use temp files (e.g. in /tmp) that are deleted when the application stops. For development purposes.
path	String	---	✅	The absolute path of the directory on the file system of the essencium application to use to store files.

s3

Config parameters for the s3 provider.

parameter	type	default	required	comment
active	boolean	false		Setting active to true tells the spring application to include components needed for the s3 storage provider in its component and entity scan. A file stored with the s3 provider cannot be loaded if active is not set to true.
endpointUrl	String	---		Defines the endpoint URI to be used, e.g. "http://127.0.0.1:9000" can be used to access a local S3-bucket using MinIo
region	String	---		Defines the AWS-Region the s3-bucket is located. All regions from com.amazonaws.regions.Regions are accepted.
bucketName	String	---	✅	Defines the name of the s3-bucket to be used. If there is no bucket with the given name, one is created.
accessKey	String	---		Access Key defined by your s3-bucket host
secretKey	String	---		Secret Key defined by your s3-bucket host

If endpointUrl, accessKey and secretKey are not provided, the aws default credentials provider chain is used. For non-AWS S3-Buckets, the endpointUrl, accessKey and secretKey have to be set to the S3-Endpoint and Credentials of the host.

Requirements

• JDK 17
• Maven

Testing

The backend lib comprises both unit- and integration tests.

• Unit Tests: mvn test
• Integration Tests: mvn failsafe:integration-test

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Frachtwerk GmbH