def METHOD_NAME(tenant_id, vault_client_id, client_secret=None):
    """ Get the vault access token to get all the other passwords/secrets.  """
    vaulttoken = None
    if client_secret:
        vault_client_secret = client_secret if client_secret else None
        data = {
            'grant_type': 'client_credentials',
            'client_id': vault_client_id,
            'client_secret': vault_client_secret,
            'resource': 'https://vault.azure.net'
        }
        hdrs = {
            'Cache-Control': "no-cache",
            "Accept": "application/json"
        }
        if tenant_id:
            url = 'https://login.microsoftonline.com/%s/oauth2/token' % tenant_id
            status, data = http_post_request(url, data, headers=hdrs)
            if status and isinstance(status, int) and status == 200:
                vaulttoken = data['access_token']
    return vaulttoken