custom-hashicorp-vault/setup-scripts/app-role-access.py

#!/usr/bin/env python3

# |*******************************************************************|
# | Setup script                                                      |
# |                                                                   |
# | Author: Alan Bridgeman                                            |
# | Created: 2024-03-30                                               |
# |                                                                   |
# | COPYRIGHT © 2024 Bridgeman Accessible/Alan Bridgeman.             |
# |                                                                   |
# | This work is presented AS IS, with no warranty of any kind.       |
# | Any modification or use of this script is at the user's own risk. |
# |*******************************************************************|

import os, sys, subprocess, json, logging

from CommandRunner import CommandRunner

#def run_command(command):
#    try:
#        result = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, check=True)
#        return result.stdout.decode('utf-8').strip()
#    except subprocess.CalledProcessError as e:
#        # Log the error and re-raise or handle as appropriate
#        raise RuntimeError(f"Command '{' '.join(command)}' failed with error: {e.stderr}") from e

def check_app_role_enabled():
    """Check if the AppRole auth method is enabled in vault

    Returns:
        bool: True if AppRole is enabled, False otherwise
    """

    # List the enabled auth methods
    auth_return_code, auth_output, auth_err = CommandRunner.run_command('vault auth list -format=json')

    # If non-zero return code, raise an error
    if auth_return_code != 0:
        logging.error('Failed to list auth methods')
        logging.error('Auth Output: ' + auth_output)
        logging.error('Auth Error: ' + auth_err)
        raise RuntimeError('Failed to list auth methods')
    
    # Parse the output
    auth_methods = json.loads(auth_output)

    # Use the existence of the 'approle/' key to determine if AppRole is enabled
    return 'approle/' in auth_methods

def check_policy_exists(policy_name: str) -> bool:
    """Check if a policy exists in vault

    Args:
        policy_name (str): The name of the policy to check
    Returns:
        bool: True if the policy exists, False otherwise
    """
    
    # List the policies
    policy_return_code, policy_output, policy_err = CommandRunner.run_command('vault policy list -format=json')

    # If non-zero return code, raise an error
    if policy_return_code != 0:
        logging.error('Failed to list policies')
        logging.error('Policy Output: ' + policy_output)
        logging.error('Policy Error: ' + policy_err)
        raise RuntimeError('Failed to list policies')
    
    # Parse the output
    policies = json.loads(policy_output)

    # Check if the policy name exists in the returned list
    return policy_name in policies

def create_policy(policy_name: str, policy_capabilities: list[str], policy_path: str = 'secret/*'):
    """Create a policy in vault

    Args:
        policy_name (str): The name of the policy to create
        policy_capabilities (list[str]): The capabilities of the policy (ex. read, write, etc...)
        policy_path (str, optional): The path the policy should apply to. Defaults to all secrets (`secret/*`).
    """

    # Create the "policy file" that is specified on the command line
    policy_caps = '["' + '","'.join(policy_capabilities) + '"]'
    policy_content = 'path "' + policy_path + '" {\n  capabilities = ' + policy_caps + '\n}'
    policy = '<<EOF\n' + policy_content + '\nEOF'

    # Write the policy to vault
    policy_return_code, policy_output, policy_err = CommandRunner.run_command('vault policy write ' + policy_name + ' - ' + policy, False)
    
    # If non-zero return code, raise an error
    if policy_return_code != 0:
        logging.error('Failed to create the policy')
        logging.error('Policy Output: ' + policy_output)
        logging.error('Policy Error: ' + policy_err)
        raise RuntimeError('Failed to create the policy')

def check_app_role_exists(role_name: str) -> bool:
    """Check if an AppRole role exists in vault

    Args:
        role_name (str): The name of the role to check
    Returns:
        bool: True if the role exists, False otherwise
    """
    
    # To use `vault list`, we need to specify the "path" (which is a slash separated string dictating the hierarchy to the thing we want to list)
    role_list_path = '/' + '/'.join(['auth', 'approle', 'role'])
    
    # List the roles
    role_return_code, role_output, role_err = CommandRunner.run_command(f'vault list --format=json {role_list_path}', False)

    # If non-zero return code, raise an error
    if role_return_code != 0:
        logging.error('Failed to list AppRole roles')
        logging.error('Role Output: ' + role_output)
        logging.error('Role Error: ' + role_err)
        #raise RuntimeError('Failed to list AppRole roles')
    
    # Parse the output
    roles = json.loads(role_output)

    # Check if the role name exists in the returned list
    return role_name in roles

def get_role_id(role_name: str) -> str:
    """Get the `role_id` for a given role

    Args:
        role_name (str): The name of the role to get the `role_id` for

    Returns:
        str: The `role_id` for the given role
    """

    # The read path for the role_id of the given role (path being a slash separated string dictating the hierarchy to the thing we want to read)
    role_read_path = '/'.join(['auth', 'approle', 'role', role_name, 'role-id'])
    
    # Get the role_id from vault
    # Note, check is enabled so any non-zero return code will raise an error
    role_return_code, role_id_output, role_id_err = CommandRunner.run_command('vault read --format=json ' + role_read_path)
    
    # Parse the role_id from the output
    role_id_json = json.loads(role_id_output)
    role_id = role_id_json['data']['role_id']

    logging.debug('Role ID: ' + role_id)

    return role_id

def get_secret_id(role_name: str) -> str:
    """Get a/the `secret_id` for a given role

    Args:
        role_name (str): The name of the role to get the `secret_id` for

    Returns:
        str: The `secret_id` for the given role
    """

    # The write path for the secret_id of the given role (path being a slash separated string dictating the hierarchy to the thing we want to write)
    secret_write_path = '/'.join(['auth', 'approle', 'role', role_name, 'secret-id'])
    
    # Get the secret_id from vault (by writing to the secret-id endpoint)
    # Note, check is enabled so any non-zero return code will raise an error
    secret_return_code, secret_id_output, secret_id_err = CommandRunner.run_command('vault write --format=json -f ' + secret_write_path)

    # Parse the secret_id from the output
    secret_id_json = json.loads(secret_id_output)
    secret_id = secret_id_json['data']['secret_id']

    logging.debug('Secret ID: ' + secret_id)

    return secret_id

def create_app_role(role_name: str, policy_name: str) -> tuple[str, str]:
    """Create an approle role and return the role_id and secret_id

    Args:
        role_name (str): The name of the role to create
        policy_name (str): The name of the policy to associate with the role

    Returns:
        tuple[str, str]: The `role_id` and `secret_id` of the newly created role
    """

    # The write path for creating the role (path being a slash separated string dictating the hierarchy to the thing we want to write)
    role_write_path = '/'.join(['auth', 'approle', 'role', role_name])

    # Create a role
    # Note, check is enabled so any non-zero return code will raise an error
    role_write_return_code, role_write_output, role_write_err = CommandRunner.run_command('vault write ' + role_write_path + ' token_policies="' + policy_name + '"')

    logging.debug(role_write_output)

    # Get the role_id
    role_id = get_role_id(role_name)
    
    # Get the secret_id
    secret_id = get_secret_id(role_name)
    
    return role_id, secret_id

def save_role_vars_to_backup_file(role_name: str, role_id: str, secret_id: str):
    """Save the role_id and secret_id to a backup file (in the `/vault/creds` directory which is mounted to the host)

    This is used as a sort of backup in rare case where the `/role_vars/.env` doesn't persist across restarts/instances.

    Args:
        role_name (str): The name of the role (used as the filename inside of the `/vault/creds` directory)
        role_id (str): The `role_id` to save
        secret_id (str): The `secret_id` to save
    """
    
    file_name = f'/vault/creds/{role_name}'
    
    logging.debug('File Name: ' + file_name)
    
    # Create the file if it doesn't exist
    if not os.path.isfile(file_name):
        CommandRunner.run_command('touch "' + file_name + '"')
    
    # Write the role_id and secret_id to the file
    with open(file_name, 'w+') as f:
        f.write('='.join([os.environ['ROLE_ID_SECRET_NAME'], role_id]) + '\n')
        f.write('='.join([os.environ['SECRET_ID_SECRET_NAME'], secret_id]))

def save_role_vars_to_file(role_id: str, secret_id: str):
    """Save the role_id and secret_id to a file (`/role_vars/.env`)

    This file can then be loaded/mounted/etc... into other containers or by other scripts to load the values so that the app can load it

    Args:
        role_id (str): The `role_id` to save
        secret_id (str): The `secret_id` to save
    """

    # Create the directory if it doesn't exist
    if not os.path.isdir('/role_vars'):
        os.mkdir('/role_vars')
    
    file_name = '/role_vars/.env'
    
    logging.debug('File Name: ' + file_name)
    
    # Create the file if it doesn't exist
    if not os.path.isfile(file_name):
        CommandRunner.run_command('touch "' + file_name + '"')
    
    # Write the role_id and secret_id to the file
    with open(file_name, 'w+') as f:
        f.write('='.join([os.environ['ROLE_ID_SECRET_NAME'], role_id]) + '\n')
        f.write('='.join([os.environ['SECRET_ID_SECRET_NAME'], secret_id]))

def main(token: str):
    #logging.basicConfig(
    #    filename='/var/log/entrypoint.log',
    #    level=logging.DEBUG,
    #    format='%(asctime)s - %(levelname)s - %(message)s'
    #)

    # Login to vault
    CommandRunner.run_command(f'vault login {token}')

    if not check_app_role_enabled():
        # Enable approle auth method
        CommandRunner.run_command('vault auth enable approle')
    
    # -- Create a policy for the app --
    
    # The policy name can be set via the `POLICY_NAME` environment variable
    # Or defaults to `node-app-policy` if not set
    if 'POLICY_NAME' in os.environ:
        policy_name = os.environ['POLICY_NAME']
    else:
        policy_name = 'node-app-policy'

    logging.debug(f'Policy Name: {policy_name}')
    
    if not check_policy_exists(policy_name):
        # The policy capabilities can be set via the `POLICY_CAPABILITIES` environment variable
        # Or defaults to `['read', 'create', 'update']` if not set
        if 'POLICY_CAPABILITIES' in os.environ:
            policy_capabilities = [cap.strip() for cap in os.environ['POLICY_CAPABILITIES'].split(',')] 
        else:
            policy_capabilities = ['read', 'create', 'update']

        logging.debug(f'Policy Capabilities: {', '.join(policy_capabilities)}')

        create_policy(policy_name, policy_capabilities)

    # -- create an approle role --

    # The role name can be set via the `ROLE_NAME` environment variable
    # Or defaults to `node-app` if not set
    if 'ROLE_NAME' in os.environ:
        role_name = os.environ['ROLE_NAME']
    else:
        role_name = 'node-app'
    
    if not check_app_role_exists(role_name):
        # Create a role
        role_id, secret_id = create_app_role(role_name, policy_name)

        # Save the role_id and secret_id to a backup file
        save_role_vars_to_backup_file(role_name, role_id, secret_id)

        # Save the role_id and secret_id to a file
        save_role_vars_to_file(role_id, secret_id)
    else:
        # Get the existing role_id and secret_id
        role_id = get_role_id(role_name)
        secret_id = get_secret_id(role_name)

        # Save the role_id and secret_id to a file
        # QUESTION: Should this be conditional on if the file already exists or not?
        save_role_vars_to_file(role_id, secret_id)
    
    logging.info('AppRole setup complete')

if __name__ == '__main__':
    # Parse the root token (used to login) from the command line arguments
    token = sys.argv[1]

    # Run the script's main function
    main(token)