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Sanitizing databases: PostgreSQL and Symfony

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Databases of live websites often contain personally identifiable information (PII) such as full names, mailing addresses, and phone numbers. To ensure people reviewing code changes can’t access information they shouldn’t, sanitize your databases of any PII that they may contain.

This example goes through the process for a PostgreSQL database using Symfony.

Before you begin Anchor to this heading

You need:

  • A project with a PostgreSQL database.
  • A command interface installed:
    • If doing it manually, the Symfony CLI.
    • Otherwise, make sure pqsl is installed in your environment.

This guide is about sanitizing PostgreSQL databases.

This guide doesn’t address:

  • Sanitizing NoSQL Databases (such as MongoDB)
  • Input validation and input sanitization, which both help prevent security vulnerabilities

Sanitize the database Anchor to this heading

Make sure that you only sanitize preview environments and never the production environment. Otherwise you may lose most or even all of the relevant data stored in your database.

First, take a database dump of your preview environment. This is just a safety precaution. Production data isn’t altered. To get a database dump, run the following command: symfony db:dump -e DEVELOPMENT_ENVIRONMENT_NAME .

Assumptions:

  • users is the table where all of your PII is stored in the staging development database.
  • staging is an exact copy of your production database.
  1. Connect to the staging database by running symfony sql -e staging.

  2. Display all fields from your users table, to select which ones need to be redacted. Run the following query:

    main=> SELECT * FROM users;

    You see output like the following:

    id   |                user_email               |     display_name
    -----+-----------------------------------------+-----------------------
    3501 | daniel02@yourcompany.com                | Jason Brown
    3502 | ismith@kim.com                          | Sandra Griffin
    3503 | olee@coleman-rodriguez.com              | Miss Christine Morgan
  3. Change the fields where PII is contained with the UPDATE statement. For example, to change the display name of users with an email address not in your company’s domain to a random value, run the following query:

    UPDATE users
    SET display_name==substring(md5(display_name||'$PLATFORM_PROJECT_ENTROPY') for 8);
    WHERE email NOT LIKE '%@yourcompany%'

    Adapt and run that query for all fields that you need to sanitize. If you modify fields that you shouldn’t alter, you can restore them from the dump you took in step 1.

    You can create a script to automate the sanitization process to be run automatically on each new deployment. Once you have a working script, add your script to sanitize the database to a deploy hook:

    .platform.app.yaml
    hooks:
        deploy: |
            cd /app/public
            if [ "$PLATFORM_ENVIRONMENT_TYPE" = production ]; then
                # Do whatever you want on the production site.
            else
                # The sanitization of the database should happen here (since it's non-production)
                sanitize_the_database.sh
            fi        

Assumptions:

  • An Entity User exist and contains all of your PII (Personally Identifiable Information)
  • fakerphp/faker has been installed as a dependency on your Symfony application

Set up a script by following these steps:

  1. Create a Symfony command to sanitize data

    src/Command/SanitizeDataCommand.php
    <?php
    namespace App\Command;
    
    use App\Entity\User;
    use App\Repository\UserRepository;
    use Doctrine\ORM\EntityManagerInterface;
    use Faker;
    use Symfony\Component\Console\Command\Command;
    use Symfony\Component\Console\Input\InputInterface;
    use Symfony\Component\Console\Output\OutputInterface;
    use Symfony\Component\Console\Style\SymfonyStyle;
    
    class SanitizeDataCommand extends Command
    {
        protected static $defaultName = 'app:sanitize-data';
    
        protected static $defaultDescription = 'Sanitize user data (username and email).';
    
        public function __construct(
          private UserRepository $userRepository,
          private EntityManagerInterface $entityManager
        )
        {
            parent::__construct();
        }
    
        protected function configure()
        {
            $this->setDescription('This command allows you to sanitize user data (username and email).');
        }
    
        protected function execute(InputInterface $input, OutputInterface $output)
        {
            $io = new SymfonyStyle($input, $output);
    
            $users = $this->userRepository->findAll();
            $io->progressStart(count($users));
    
            /** @var User $user */
            foreach ($users as $user) {
                $io->progressAdvance();
    
                // initialize faker
                $faker = Faker\Factory::create();
    
                // sanitize user info
                $user->setUsername(uniqid($faker->userName()));
                $user->setEmail($faker->email());
                // adapt to your needs
    
                $this->entityManager->flush();
            }
            $io->progressFinish();
    
            return static::SUCCESS;
        }
    }
  2. Update the deploy hook to run your Symfony Command on each deploy.

    .platform.app.yaml
    hooks:
        build: ...
        deploy: |
        if [ "$PLATFORM_ENVIRONMENT_TYPE" != production ]; then
            # The sanitization of the database should happen here (since it's non-production)
            php bin/console app:sanitize-data
        fi    

    To sanitize only on the initial deploy and not all future deploys, on sanitization create a file on a mount. Then add a check for the file as in the following example:

    .platform.app.yaml
    hooks:
        build: ...
        deploy: |
        if [ "$PLATFORM_ENVIRONMENT_TYPE" != production ] && [ ! -f MOUNT_PATH/is_sanitized ]; then
            # The sanitization of the database should happen here (since it's non-production)
            php bin/console app:sanitize-data
            touch MOUNT_PATH/is_sanitized
        fi    
  3. Commit your changes by running the following command:

    git add src/Command/SanitizeDataCommand.php .platform.app.yaml && git commit -m "Add sanitization."

    Push the changes to staging and verify that environment’s database was sanitized. Once merged to production, all data from future preview environments are sanitized on environment creation.

This example show you how to sanitize data on multiple projects inside an organization, except for production environments.

Assumptions:

  • Symfony Command from previous tab Using a Symfony Command has already been pushed to all of your environments.

Set up a script by following these steps:

  1. Create an executable sanitizing script by running the following command:

    touch sanitize_fleet.sh && chmod +x sanitize_fleet.sh
  2. Make the script sanitize environments with an environment type other than production.

    The following example runs only in preview environments and sanitizes data using the Symfony Command from previous tab, already pushed to all of your environments.

    sanitize_fleet.sh
    if [ -n "$ZSH_VERSION" ]; then emulate -L ksh; fi
    ######################################################
    # fleet sanitization demo script, using the Symfony CLI.
    #
    # Enables the following workflow on a project:
    # .
    # └── main
    #     β”œβ”€β”€ staging
    #     |   └── new-feature
    #     └── auto-updates
    #
    # Usage
    # 1. source this script: `. sanitize_fleet.sh` or `source sanitize_fleet.sh` depending of your local machine
    # 2. define ORGANIZATION var: ORGANIZATION=<organizationIdentifier>
    # 3. run `sanitize_organization_data $ORGANIZATION`
    ######################################################
    
    # Utility functions.
    
    # list_org_projects: Print list of projects operation will be applied to before starting.
    #   $1: Organization, as it appears in console.platform.sh.
    list_org_projects () {
       symfony project:list -o $1 --columns="ID, Title"
    }
    
    # get_org_projects: Retrieve an array of project IDs for a given organization.
    #   Note: Makes array variable PROJECTS available to subsequent scripts.
    #   $1: Organization, as it appears in console.platform.sh.
    get_org_projects () {
      PROJECTS_LIST=$(symfony project:list -o $1 --pipe)
      PROJECTS=($PROJECTS_LIST)
    }
    
    # get_project_envs: Retrieve an array of envs IDs for a project.
    #   Note: Makes array variable ENVS available to subsequent scripts.
    #   $1: ProjectId, as it appears in console.platform.sh.
    get_project_envs () {
      ENV_LIST=$(symfony environment:list -p $1 --pipe)
      ENVS=($ENV_LIST)
    }
    
    # list_project_envs: Print list of envs operation will be applied to before starting.
    #   $1: ProjectId, as it appears in console.platform.sh.
    list_project_envs () {
      symfony environment:list -p $1
    }
    
    # add_env_var: Add environment level environment variable.
    #   $1: Variable name.
    #   $2: Variable value.
    #   $3: Target project ID.
    #   $4: Target environment ID.
    add_env_var () {
      VAR_STATUS=$(symfony project:curl -p $3 /environments/$4/variables/env:$1 | jq '.status')
      if [ "$VAR_STATUS" != "null" ]; then
        symfony variable:create \
        --name $1 \
        --value "$2" \
        --prefix env: \
        --project $3 \
        --environment $4 \
        --level environment \
        --json false \
        --sensitive false \
        --visible-build true \
        --visible-runtime true \
        --enabled true \
        --inheritable true \
        -q
      else
        printf "\nVariable $1 already exists. Skipping."
      fi
    }
    
    # Main functions.
    sanitize_organization_data () {
      list_org_projects $1
      get_org_projects $1
      for PROJECT in "${PROJECTS[@]}"
      do
        printf "\n### Project $PROJECT."
        # get environments list
        list_project_envs $PROJECT
        get_project_envs $PROJECT
        for ENVIRONMENT in "${ENVS[@]}"
        do
          unset -f ENV_CHECK
          ENV_CHECK=$(symfony project:curl -p $PROJECT /environments/$ENVIRONMENT | jq -r '.status')
          unset -f ENV_TYPE
          ENV_TYPE=$(symfony project:curl -p $PROJECT /environments/$ENVIRONMENT | jq -r '.type')
    
          if [ "$ENV_CHECK" = active -a "$ENV_TYPE" != production ]; then
            unset -f DATA_SANITIZED
            DATA_SANITIZED=$(symfony variable:get -p $PROJECT -e $ENVIRONMENT env:DATA_SANITIZED --property=value)
            if [ "$DATA_SANITIZED" != true ]; then
              printf "\nEnvironment $ENVIRONMENT exists and isn't sanitized yet. Sanitizing data."
              printf "\n"
              # do sanitization here
              symfony ssh -p $PROJECT -e $ENVIRONMENT -- php bin/console app:sanitize-data
              printf "\nSanitizing data is finished, redeploying"
              add_env_var DATA_SANITIZED true $PROJECT $ENVIRONMENT
            else
              printf "\nEnvironment $ENVIRONMENT exists and doesn't need to be sanitized. skipping."
            fi
          elif [ "$ENV_TYPE" == production ]; then
            printf "\nEnvironment $ENVIRONMENT is production one, skipping."
          else
            printf "\nEnvironment $ENVIRONMENT isn't active $ENV_CHECK, skipping."
          fi
        done
      done
    }
  3. use this shell script

    Depending on the machine you want to run this script on, adapt this to your needs.

    . sanitize_fleet.sh  # or source sanitize_fleet.sh
    ORGANIZATION=<organizationIdentifier>
    sanitize_organization_data $ORGANIZATION
  1. [Option] Commit your changes by running the following command:

    git add sanitize_fleet.sh && git commit -m "Add sanitization."

    Push the changes to staging and verify that environment’s database was sanitized. Once merged to production, all data from future preview environments are sanitized on environment creation.

What’s next Anchor to this heading

You learned how to remove sensitive data from a database.

To replace sensitive data that with other meaningful data, you can add a faker to the process. A faker is a program that generates fake data that looks real. Having meaningful PII-free data allows you to keep your current Q&A, external reviews, and other processes. To add a faker, adapt your sanitizing queries to replace each value that contains PII with a new value generated by the faker.

You might also want to make sure that you implement input validation.

If your database contains a lot of data, consider using the REINDEX statement to help improve performance.

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