DDB Cover Service Importers

This is the indexer and cover importer for DDB Cover Service.

Architecture Overview

The DDB COver Service application consists of multiple logical parts with individual repositories:

This repository:

An CLI based image import/index/upload engine that handles import, indexing and uploading of cover images from external providers.

Other repositories:

Tech Stack

This is a Symfony 5 (flex) project.

Server/hosting reference requirements: PHP 7.4, Nginx 1.14, MariaDB 10.3, ElasticSearch 6.8, Redis Server 6, RabbitMQ 3.9.

The application is currently developed and hosted on this stack. However, the individual components can be swapped for relevant alternatives. Apache can be used instead of Nginx. Any database supported by Doctrine DBAL such as MySQL or PostgreSQL can replace MariaDB. Redis is used as caching layer for Symfony. Both support multiple other persistence layers such as memcache and RabbitMQ, respectively, and can be changed as needed.

Application components:

Symfony 5 (flex) - underlying Web Application framework
Doctrine 2 - database DBAL/ORM layer
RabbitMq - RabbitMQ is used for async jobs

External Services:

Cloudinary is used as CDN and transformation engine for all cover images
Open Search is used for mapping between common ids (isbn etc.) and library specific id's such as 'pid' and 'faust'

Messaging

For performance reasons both parts are designed around a messaging-based architecture to allow for asynchronous handling of tasks. For the API this means that any task not strictly needed for the response such as various logging tasks are deferred and handled after the request/response. For the import engine only the initial read from source is done synchronously. For each imported cover image individual index and upload jobs are created and run later.

Services and Dependency Injection

All internal functionality is defined as individual services. These are autowired through dependency injection by Symfony's Service Container

Persistence

The import engine defines a number of entities for storing relevant data on imports and images. These are mapped to and persisted in the database through doctrine. Further a 'search' entity is defined with the fields exposed by the REST API. This entity is mapped one-to-one to an index in ElasticSearch.

Logging and Statistics

The application logs to ElasticSearch to allow debugging and monitoring. A stats_dd-mm-yyyy is created daily. To ensure that Elastic chooses the right type for the index fields a dynamic index template must be added to Elastic. This can be done with the app:elastic:create-stats-template command.

Low disk

If you have less than 10% disk space left elastic search will not index content and switchs into read-only mode. This command will disable this behaviour:

curl -XPUT http://0.0.0.0:<PORT>/_cluster/settings -H 'Content-Type: application/json' -d '{"transient":{"cluster.routing.allocation.disk.threshold_enabled":fals }}'

Implementation Overview

Import/Index/Upload Engine

The overall flow of the consist of import -> upload -> index:

For each Vendor the full list of available materials is read. Each found material is saved as Source and a ProcessMessage is generated with VendorImageTopic and id => image URL
Each image URL is validated and it's verified that the remote image exists. If the image is found the ProcessMessage is forwarded with a CoverStoreTopic and Source is updated with relevant metadata.
Each image is added to Cloudinary through their API. This enables us to just instruct Cloudinary to fetch the image from the image URL and add to the Media Library. An Image is created containing Cloudinary metadata and an ProcessMessage with SearchTopicis sent.
A search is made in Open Search to determine what id 'aliases' the image should be indexed under. We know the ISxx from the Vendor but to build index entries for PID and FAUST we need to match these through Open Search. For each id a new Search entry is made which is automatically synced to ElasticSearch.

Vendors

The application needs to import covers from a number of different vendors through their exposed access protocols. This means we need to support various strategies such as crawling zip-archives via ftp, parsing excel files and accessing APIs. Individual VendorServices are defined for each vendor to support their respective data access. These all extend AbstractBaseVendorService were common functionality needed by the importers is defined.

All vendor implementations are located under /src/Service/VendorService/*

Services

The application defines a number of internal services for the various tasks. These are autowired through dependency injection by Symfony's Service Container

CoverStore

Abstracts Cloudinarys Upload API functionality into a set of helper methods for upload, delete and generate. "Generate" will create a generic cover based on a default image.

OpenPlatform

Implements authentication and search against Open Search

Vendor Services

Common functionality for all Vendor importers is shared in AbstractBaseVendorService. Individual importers are defined for each vendor to contain the import logic for the vendors specific access setup (FTP/Spreadsheet/API etc).

Development Setup

Docker compose

The project comes with a docker-compose setup base on development only images, that comes with all required extensions to PHP (including xdebug) and all services required to run the application.

For easy usage it's recommended to use træfik (proxy) and the wrapper script for docker-compose used at ITKDev (https://github.com/aakb/itkdev-docker/tree/develop/scripts). It's not an requirement and the setup examples below is without the script. The script just makes working with docker simpler and faster.

Running docker setup

Start the stack.

docker-compose up --detach

All the symfony commands below to install the application can be executed using this pattern.

docker-compose exec phpfpm bin/console <CMD>

Install

We assume you have a working local/vagrant/docker web server setup with PHP, Nginx, MariaDB, ElasticSearch and Redis.

Checkout the project code from GitHub and run composer install from the project root dir
Create a /.env.local file and define the relevant environment variables to match your setup
Run migrations bin/console doctrine:migrations:migrate
Create ES search index bin/console fos:elastica:create
Run vendor/bin/phpunit to ensure your test suite is working.
Run bin/console app:vendor:populate to populate the vendor tables with the implemented vendors.
Add relevant access config to the vendor table

Application can now load vendors through the bin/console app:vendor:load command. The application is purely a job queue and command based. No API or site is exposed through http(s).

Development

Doctrine Migrations

The project uses Doctrine Migrations to handle updates to the database schema. Any changes to the schema should have a matching migration. If you make changes to the entity model you should run bin/console doctrine:migrations:diff to generate a migration with the necessary sql statements. Review the migration before executing it with bin/console doctrine:migrations:migrate

After changes to the entity model and migrations always run bin/console doctrine:schema:validate to ensure that mapping is correct and database schema is in sync with the current mapping file(s).

Commands

To simplify testing during development test console commands are defined for the various services defined in the application. These are described for each service in the "Services" section of this document. Using these commands you can manually test each service in isolation without having to run one or more message queues.

OpenPlatform Authentication

Simple command to test that the authentication service is working and has the correct configuration in the environment.

bin/console app:openplatform:auth

OpenPlatform Search

This command runs a search into the open platform datawell. The last parameter if set will by-pass the cache. The command will output the search result.

bin/console app:openplatform:search --type=isbn --identifier=9788702173277

Cover Store

This command will upload an image into the cover store.

bin/console app:cover:upload <IMAGE URL> <FOLDER> <TAG(s)>

Vendor commands

This runs the importer for the configured vendors. The command will prompt for which vendors to import.

bin/console app:vendor:load

Please note: To ensure that the command run with a "flat" memory foot print in production you must run it with --no-debug in the prod environment.

Production

bin/console app:vendor:load --env=prod --no-debug

Note: For some Vendors proper access credentials need to be set in the database before running an import. To populate the Vendor table you can run:

bin/console app:vendor:populate

This will create an entry for each defined vendor service that extends AbstractBaseVendorService. However, you must manually add the relevant credentials to each row in the database.

Vendor event

This command will fire an insert event an place an job into the message queue system that will import an image into Cover Store and update the search index.

bin/console app:vendor:event insert 9788702173277 ISBN 1

Message queues

The application defines a number of job queues for the various background tasks and is configured to use Redis as the persistence layer for queues/messages. To have a fully functioning development setup you will need to run consumers for all queues. See the Symfony docs for more information about the Messenger Component.

To run consumers for all queues do

bin/console messenger:consume --env=prod --quiet --time-limit=900 --failure-limit=1 async_priority_high
bin/console messenger:consume --env=prod --quiet --time-limit=900 --failure-limit=1 async_priority_normal
bin/console messenger:consume --env=prod --quiet --time-limit=900 --failure-limit=1 async_priority_low
bin/console messenger:consume --env=prod --quiet --time-limit=900 --failure-limit=1 async_no_hit

Or use all your works to run all queue in the order given (from high to no-hit).

bin/console messenger:consume --env=prod --quiet --time-limit=900 --failure-limit=1 async_priority_high \
async_priority_normal async_priority_low async_no_hit

Message Queues and Doctrine

If Doctrine throws an exception when interacting with the database the Consumers' Entity Manager will close and not re-open. This will cause subsequent message handling to fail. To handle this run the consumers with --failure-limit=1. This will cause the consumer to exit if an exception is thrown. The Consumer will then be restarted with a new Entity Manager assuming Supervisor or similar is used to run the consumers.

See: Symfony PR #35453

Testing

The application has a test suite consisting of unit tests.

To run the unit tests located in /tests you can run:

docker compose exec phpfpm composer install
docker compose exec phpfpm ./vendor/bin/phpunit

Both bugfixes and added features should be supported by matching tests.

Psalm static analysis

We are using Psalm for static analysis. To run psalm do

docker compose exec phpfpm composer install
docker compose exec phpfpm ./vendor/bin/psalm

Check Coding Standard

The following command let you test that the code follows the coding standard for the project.

PHP files (PHP-CS-Fixer)

docker compose exec phpfpm composer check-coding-standards

Markdown files (markdownlint standard rules)

docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app node:18 yarn install
docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app node:18 yarn coding-standards-check

Apply Coding Standards

To attempt to automatically fix coding style

PHP files (PHP-CS-Fixer)

docker compose exec phpfpm composer apply-coding-standards

Markdown files (markdownlint standard rules)

docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app node:18 yarn install
docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app node:18 yarn coding-standards-apply

CI

Github Actions are used to run the test suite and code style checks on all PR's.

If you wish to test against the jobs locally you can install act. Then do:

act -P ubuntu-latest=shivammathur/node:latest pull_request

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

License

This project is licensed under the AGPL-3.0 License - see the LICENSE.md file for details

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