pay-ledger

This is a bare bones Dropwizard App for the Pay Ledger microservice.

API Specification

The API Specification provides more detail on the paths and operations including examples.

View the API specification for ledger in Swagger Editor.

Environment variables

There are several environment variables used for the app configuration. They're grouped in categories: database, SQS and background processing.

Variable	Default	Purpose
BIND_HOST	127.0.0.1	The IP address for the application to bind to
PORT	-	Port on which application listens

Database configuration

Variable	Default	Purpose
DB_USER	-	Name of the user used to connect to the database
DB_PASSWORD	-	Password of the user used to connect to the database
DB_HOST	-	Database host name
DB_NAME	ledger	Name of the database
DB_SSL_OPTION	-	Indicates whether the connection to the database should be secured with SSL (eg. ssl=true)

AWS Credentials Configuration

Variable	Default	Purpose
AWS_ACCESS_KEY	-	Access key. Only required when AWS_SQS_NON_STANDARD_SERVICE_ENDPOINT or AWS_SNS_NON_STANDARD_SERVICE_ENDPOINT is true
AWS_SECRET_KEY	-	Secret key. Only required when AWS_SQS_NON_STANDARD_SERVICE_ENDPOINT or AWS_SNS_NON_STANDARD_SERVICE_ENDPOINT is true

SQS configuration

Variable	Default	Purpose
AWS_SQS_REGION	-	SQS region
AWS_SQS_PAYMENT_EVENT_QUEUE_URL	-	SQS payment event queue URL
AWS_SQS_MESSAGE_MAXIMUM_WAIT_TIME_IN_SECONDS	20	Maximum wait time for long poll message requests to queue
AWS_SQS_MESSAGE_MAXIMUM_BATCH_SIZE	10	Maximum number of messages that should be received in an individual message batch
AWS_SQS_NON_STANDARD_SERVICE_ENDPOINT	false	Set to true to use a non standard (eg: http://my-own-sqs-endpoint) SQS endpoint
AWS_SQS_ENDPOINT	-	URL that is the API endpoint for SQS. Only required when AWS_SQS_NON_STANDARD_SERVICE_ENDPOINT is true

SNS Configuration

Variable	Default	Purpose
SNS_ENABLED	false	Set to true to send events to SNS
AWS_SNS_REGION	-	SNS region
AWS_SNS_NON_STANDARD_SERVICE_ENDPOINT	false	Set to true to use a non standard (eg: http://my-own-sns-endpoint) SNS endpoint
AWS_SNS_ENDPOINT	-	URL that is the API endpoint for SNS. Only required when AWS_SNS_NON_STANDARD_SERVICE_ENDPOINT is true
PUBLISH_CARD_PAYMENT_EVENTS_TO_SNS	false	Set to true to publish card payment events to the card payment events SNS topic
PUBLISH_CARD_PAYMENT_DISPUTE_EVENTS_TO_SNS	false	Set to true to publish card payment dispute events to the card payment dispute events SNS topic
SNS_TOPIC_CARD_PAYMENT_EVENTS_ARN	-	ARN of the SNS topic for card payment events
SNS_TOPIC_CARD_PAYMENT_DISPUTE_EVENTS_ARN	-	ARN of the SNS topic for card payment dispute events

Expunge/Redact historic data configuration

Variable	Default	Purpose
EXPUNGE_AND_REDACT_HISTORICAL_DATA_ENABLED	false	Set to true to enable redacting PII from transactions and remove related events
EXPUNGE_OR_REDACT_DATA_OLDER_THAN_DAYS	2555 (7 years)	Minimum age of transactions in days that need to be redacted/expunged
EXPUNGE_NO_OF_TRANSACTIONS_PER_TASK_RUN	2500	Number of transactions to redact per task run

Background processing configuration

The background receiver will process all events that have been published to the SQS queue (AWS_SQS_PAYMENT_EVENT_QUEUE_URL).

A background thread managed by Dropwizard runs on all connector nodes. It polls the SQS payment event queue to retrieve the list of events. Processing each event involves adding a record to Event database table (unless the event is a duplicate of an event already processed, then the event is ignored).

If processing event fails it will be retried again after a specified delay (QUEUE_MESSAGE_RETRY_DELAY_IN_SECONDS). It is achieved by setting up the visibility timeout with the delay value which prevents consumers from receiving the message. After this timeout the message becomes visible for consumers again. More information of how the visibility timeout works can be found here.

The following variables control the background process:

Variable	Default	Purpose
QUEUE_MESSAGE_RECEIVER_THREAD_DELAY_IN_MILLISECONDS	1	Duration in seconds that the queue message receiver should wait between running threads
QUEUE_MESSAGE_RECEIVER_NUMBER_OF_THREADS	1	The number of polling threads started by the queue message scheduler
QUEUE_MESSAGE_RETRY_DELAY_IN_SECONDS	900	The duration in seconds that a message should be deferred before it should be retried

Licence

MIT License

Responsible Disclosure

Vulnerability Disclosure

GOV.UK Pay aims to stay secure for everyone. If you are a security researcher and have discovered a security vulnerability in this code, we appreciate your help in disclosing it to us in a responsible manner. Please refer to our vulnerability disclosure policy and our security.txt file for details.