Yeovil District Hospital NHSFT's SIDeR Contextual Link Obfuscation Service

This is Yeovil District Hospital NHSFT's contextual link obfuscation service, a Node.js application using the Fastify web framework and Black Pear's obfuscated-querystring.

This service was created out of a need for query strings parameters containing personally identifiable data to be obfuscated when users click on the SIDeR contextual link within Yeovil District Hospital NHSFT's Patient Administration System (PAS), InterSystems TrakCare.

A video demonstrating the contextual link in action can be found here.

Single sign-on for a user using access tokens from a Keycloak server instance can be enabled using environment variables found in .env.template.

• Git (to install non-registered dependencies)
• Node.js

Perform the following steps before deployment:

1. Clone the repo
2. Navigate to the project directory
3. Run npm install --ignore-scripts --production to install dependencies
4. Make a copy of .env.template in the root directory and rename it to .env
5. Configure the application using the environment variables in .env

Note: Set the following environment variables in .env to meet NHS Digital's recommendation to retain 6 months' worth of logs:

• LOG_ROTATION_DATE_FORMAT="YYYY-MM-DD"
• LOG_ROTATION_FREQUENCY="daily"
• LOG_ROTATION_MAX_LOGS="180"

1. Run npm start

The service should now be up and running on the port set in the config. You should see the following output in stdout or the log file specified using the LOG_ROTATION_FILENAME environment variable:

{
	"level": "info",
	"time": "2021-08-11T10:48:36.471Z",
	"pid": 3572,
	"hostname": "MYCOMPUTER",
	"msg": "Server listening at https://0.0.0.0:8204"
}

To quickly test it open a browser of your choice or, if using a request builder (i.e. Insomnia or Postman) create a new GET request, and input the following URL:

https://0.0.0.0:8204/redirect?patient=https://fhir.nhs.uk/Id/nhs-number|9449304513&birthdate=1934-10-23&location=https://fhir.nhs.uk/Id/ods-organization-code|RA4&practitioner=https://sider.nhs.uk/auth|[email protected]

Alternatively, you can navigate to https://0.0.0.0:8204/docs (if NODE_ENV is not set to 'production') and generate a request through the example input there.

Replace the organization code and email address in the location and practitioner query string parameters respectively with your own if you have already been set up with an account in SIDeR.

In stdout, or the log file, you will see something similar to the following returned:

{
	"level": "info",
	"time": "2021-08-11T10:49:15.608Z",
	"pid": 3572,
	"hostname": "MYCOMPUTER",
	"reqId": "req-1",
	"req": {
		"id": "req-1",
		"method": "GET",
		"url": "/redirect?patient=https%3A%2F%2Ffhir.nhs.uk%2FId%2Fnhs-number%7C9449304513&birthdate=1934-10-23&location=https%3A%2F%2Ffhir.nhs.uk%2FId%2Fods-organization-code%7CRA4&practitioner=https%3A%2F%2Fsider.nhs.uk%2Fauth%7Cfrazer.smith%40ydh.nhs.uk",
		"headers": {
			"host": "localhost:8204",
			"user-agent": "insomnia/2021.4.1",
			"accept": "text/html",
			"accept-encoding": "br, gzip, deflate"
		},
		"remoteAddress": "127.0.0.1",
		"remotePort": 52790
	},
	"msg": "incoming request"
}

{
	"level": "info",
	"time": "2021-08-11T10:49:15.628Z",
	"pid": 3572,
	"hostname": "MYCOMPUTER",
	"reqId": "req-1",
	"res": {
		"statusCode": 302,
		"headers": {
			"content-security-policy": "default-src 'self';base-uri 'self';img-src 'self' data:;object-src 'none';child-src 'self';frame-ancestors 'none';form-action 'self';upgrade-insecure-requests;block-all-mixed-content",
			"x-dns-prefetch-control": "off",
			"expect-ct": "max-age=0",
			"x-frame-options": "SAMEORIGIN",
			"strict-transport-security": "max-age=31536000; includeSubDomains",
			"x-download-options": "noopen",
			"x-content-type-options": "nosniff",
			"x-permitted-cross-domain-policies": "none",
			"referrer-policy": "no-referrer",
			"x-xss-protection": "0",
			"surrogate-control": "no-store",
			"cache-control": "no-store, max-age=0, must-revalidate",
			"pragma": "no-cache",
			"expires": "0",
			"permissions-policy": "interest-cohort=()",
			"vary": "Origin",
			"x-ratelimit-limit": 2500,
			"x-ratelimit-remaining": 2499,
			"x-ratelimit-reset": 60,
			"location": "https://pyrusapps.blackpear.com/esp/#!/launch?location=https%3A%2F%2Ffhir.nhs.uk%2FId%2Fods-organization-code%7CRA4&practitioner=https%3A%2F%2Fsider.nhs.uk%2Fauth%7Cfrazer.smith%40ydh.nhs.uk&enc=k01%7Ca6c12e7c5969ab5829a3f91ba02c302a0b4f598ad6c03709fbeeb52686a007c99f8b13add1472176b06f1471a0343f2d904d6f41c5776fa6d340834c8ebef92d41dcc164c6c8273854f404fd24b1ec8d4e6829c4a9b76aa08d8a5b63d806fb01",
			"content-length": "0"
		}
	},
	"responseTime": 19.167999982833862,
	"msg": "request completed"
}

Both the patient and birthdate query string parameters of the URL have been obfuscated in the generated redirect URL in res.headers.location.

The web browser or request builder used should be redirected to Black Pear's ESP site, and once logged in will provide the patient notes for the test patient with NHS Number 9449304513, success!

If the patient, birthdate, location or practitioner query string parameters are removed from the original URL the obfuscation process and redirect will not occur, and a 400 HTTP status code will be returned with the message similar to the following:

{
	"statusCode": 400,
	"error": "Bad Request",
	"message": "querystring should have required property 'practitioner'"
}

Likewise, if the previously mentioned query string parameters do not adhere to the types expected, an error will also be returned.

As an example, providing birthdate in an invalid date format will return the following:

{
	"statusCode": 400,
	"error": "Bad Request",
	"message": "querystring.birthdate should match format \"date\""
}

This requires Docker installed.

1. Run docker compose up (or docker compose up -d to run in background)

If you are unable to deploy this into production using Docker, it is recommended that you use a process manager such as PM2.

1. Run npm install -g pm2 to install pm2 globally
2. Launch application with pm2 start .pm2.config.js
3. Check the application has been deployed using pm2 list or pm2 monit

If using a Microsoft Windows OS utilise pm2-installer to install PM2 as a Windows service.

Note: PM2 will automatically restart the application if .env is modified.

This section is for members of the Solutions Development and Application Support teams at Yeovil District Hospital NHSFT, or other NHS Trusts that use InterSystems TrakCare as their PAS.

The SIDeR contextual link's icon profile values in TrakCare should be set to the following:

Link URL: <obfuscation service path>/redirect

Link expression: "&"_##class(Custom.ENYH.Integration.ContextualLink.GenericPatientLink).BuildURLVars("patient=https://fhir.nhs.uk/Id/nhs-number|{NHSNumber}&birthdate={DateOfBirthISO8601}&location=https://fhir.nhs.uk/Id/ods-organization-code|RA4&practitioner=https://sider.nhs.uk/auth|{UserName}@ydh.nhs.uk")

The icon itself can be found in the root of the images folder.

Contributions are welcome, and any help is greatly appreciated!

See CONTRIBUTING.md for details on how to get started. Please adhere to this project's Code of Conduct when contributing.

• Anthony Smith - Contextual link logo design
• David Suckling - Contextual link implementation and testing
• Mark Hunt - Keycloak single sign-on access tokens integration and testing
• Will Jehring - Query string obfuscation, redirect testing, and Keycloak testing

ydh-sider-obfuscation-service is licensed under the MIT license.