updated demo4 scale_out

demo2_instance_with_init_script.py

@@ -57,7 +57,6 @@ UBUNTU_IMAGE_NAME = "ubuntu-22.04-jammy-x86_64"
 #
 # id_rsa.pub should look like this (standard sshd pubkey format):
 # ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAw+J...F3w2mleybgT1w== user@HOSTNAME
-
 KEYPAIR_NAME = 'srieger-pub'
 PUB_KEY_FILE = '~/.ssh/id_rsa.pub'
 

demo3_microservice.py

@@ -1,7 +1,7 @@
 """Example for Cloud Computing Course Master AI / GSD"""
 
 # This script demonstrates how to use libcloud to start an instance in an OpenStack environment.
-# The script will create start multiple instances splitting up the faafo monolithic application into
+# The script will start multiple instances splitting up the faafo monolithic application into
 # a (minimalistic but already scalable) microservice architecture.
 # Also introduces the concept of different security groups and corresponding frontend/backend
 # separation.
@@ -55,7 +55,6 @@ UBUNTU_IMAGE_NAME = "ubuntu-22.04-jammy-x86_64"
 #
 # id_rsa.pub should look like this (standard sshd pubkey format):
 # ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAw+J...F3w2mleybgT1w== user@HOSTNAME
-
 KEYPAIR_NAME = 'srieger-pub'
 PUB_KEY_FILE = '~/.ssh/id_rsa.pub'
 

demo4-scale-out.py → demo4_scale_out.py

@@ -1,55 +1,73 @@
-# import getpass
-# import os
-# import libcloud.security
+"""Example for Cloud Computing Course Master AI / GSD"""
+
+# This script demonstrates how to use libcloud to start an instance in an OpenStack environment.
+# The script will start multiple instances splitting up the faafo monolithic application into
+# a microservice architecture with scalable api (controller) and worker instances using a
+# message queue and a database
 
+# Needed if the password should be prompted for:
+# import getpass
+import os
+import sys
 import time
+
 from libcloud.compute.providers import get_driver
 from libcloud.compute.types import Provider
 
-# reqs:
-#   services: nova, glance, neutron
-#   resources: 2 instances (m1.small), 2 floating ips (1 keypair, 2 security groups)
+# For our new Charmed OpenStack private cloud, we need to specify the path to the root
+# CA certificate
+import libcloud.security
+libcloud.security.CA_CERTS_PATH = ['./root-ca.crt']
+# Disable SSL certificate verification (not recommended for production)
+# libcloud.security.VERIFY_SSL_CERT = False
 
-# Please use 1-29 for X in the following variable to specify your group number. (will be used for the username,
-# project etc., as coordinated in the lab sessions)
+# Please use 1-29 as environment variable GROUP_NUMBER to specify your group number.
+# (will be used for the username, project etc., as coordinated in the lab sessions)
 
-group_number = 2
+group_number = os.environ.get('GROUP_NUMBER')
+if group_number is None:
+    sys.exit('Please set the GROUP_NUMBER environment variable to your group number,\n'
+             'e.g., on Windows:\n'
+             '  "$env:GROUP_NUMBER=0" or "set GROUP_NUMBER=0"\n'
+             'or on Linux/MacOS:\n'
+             '  "export GROUP_NUMBER=0" or "set GROUP_NUMBER=0"')
 
 
 # web service endpoint of the private cloud infrastructure
-auth_url = 'https://private-cloud.informatik.hs-fulda.de:5000'
+# auth_url = 'https://private-cloud.informatik.hs-fulda.de:5000'
+AUTH_URL = 'https://10.32.4.182:5000'
+# auth_url = 'https://private-cloud2.informatik.hs-fulda.de:5000'
 # your username in OpenStack
-auth_username = 'CloudComp' + str(group_number)
+AUTH_USERNAME = 'CloudComp' + str(group_number)
+print(f'Using username: {AUTH_USERNAME}\n')
 # your project in OpenStack
-project_name = 'CloudComp' + str(group_number)
+PROJECT_NAME = 'CloudComp' + str(group_number)
 # A network in the project the started instance will be attached to
-project_network = 'CloudComp' + str(group_number) + '-net'
+PROJECT_NETWORK = 'CloudComp' + str(group_number) + '-net'
 
 # The image to look for and use for the started instance
-#ubuntu_image_name = "Ubuntu 20.04 - Focal Fossa - 64-bit - Cloud Based Image"
+# ubuntu_image_name = "Ubuntu 18.04 - Bionic Beaver - 64-bit - Cloud Based Image"
 #UBUNTU_IMAGE_NAME = "auto-sync/ubuntu-jammy-22.04-amd64-server-20240319-disk1.img"
 UBUNTU_IMAGE_NAME = "ubuntu-22.04-jammy-x86_64"
 
-
-# The public key to be used for SSH connection, please make sure, that you have the corresponding private key
+# The public key to be used for SSH connection, please make sure, that you have the
+# corresponding private key
 #
 # id_rsa.pub should look like this (standard sshd pubkey format):
 # ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAw+J...F3w2mleybgT1w== user@HOSTNAME
+KEYPAIR_NAME = 'srieger-pub'
+PUB_KEY_FILE = '~/.ssh/id_rsa.pub'
 
-#keypair_name = 'CloudComp30-keypair'
-keypair_name = "srieger-pub"
-pub_key_file = '~/.ssh/id_rsa.pub'
-
-flavor_name = 'm1.small'
+FLAVOR_NAME = 'm1.small'
 
 
 # default region
-region_name = 'RegionOne'
-# domain to use, "default" for local accounts, "hsfulda" for RZ LDAP, e.g., using fdaiXXXX as auth_username
-domain_name = "default"
+REGION_NAME = 'RegionOne'
+# domain to use, "default" for local accounts, formerly "hsfulda" for LDAP accounts etc.
+# domain_name = "default"
 
 
-def main():
+def main():  # noqa: C901 pylint: disable=too-many-branches,too-many-statements,too-many-locals,missing-function-docstring
     ###########################################################################
     #
     # get credentials
@@ -68,16 +86,14 @@ def main():
     #
     ###########################################################################
 
-    # libcloud.security.VERIFY_SSL_CERT = False
-
     provider = get_driver(Provider.OPENSTACK)
-    conn = provider(auth_username,
+    conn = provider(AUTH_USERNAME,
                     auth_password,
-                    ex_force_auth_url=auth_url,
+                    ex_force_auth_url=AUTH_URL,
                     ex_force_auth_version='3.x_password',
-                    ex_tenant_name=project_name,
-                    ex_force_service_region=region_name,
-                    ex_domain_name=domain_name)
+                    ex_tenant_name=PROJECT_NAME,
+                    ex_force_service_region=REGION_NAME)
+    #               ex_domain_name=domain_name)
 
     ###########################################################################
     #
@@ -88,19 +104,19 @@ def main():
     images = conn.list_images()
     image = ''
     for img in images:
-        if img.name == ubuntu_image_name:
+        if img.name == UBUNTU_IMAGE_NAME:
             image = img
 
     flavors = conn.list_sizes()
     flavor = ''
     for flav in flavors:
-        if flav.name == flavor_name:
+        if flav.name == FLAVOR_NAME:
             flavor = conn.ex_get_size(flav.id)
 
     networks = conn.ex_list_networks()
     network = ''
     for net in networks:
-        if net.name == project_network:
+        if net.name == PROJECT_NETWORK:
             network = net
 
     ###########################################################################
@@ -112,14 +128,14 @@ def main():
     print('Checking for existing SSH key pair...')
     keypair_exists = False
     for keypair in conn.list_key_pairs():
-        if keypair.name == keypair_name:
+        if keypair.name == KEYPAIR_NAME:
             keypair_exists = True
 
     if keypair_exists:
-        print(('Keypair ' + keypair_name + ' already exists. Skipping import.'))
+        print(('Keypair ' + KEYPAIR_NAME + ' already exists. Skipping import.'))
     else:
         print('adding keypair...')
-        conn.import_key_pair_from_file(keypair_name, pub_key_file)
+        conn.import_key_pair_from_file(KEYPAIR_NAME, PUB_KEY_FILE)
 
     for keypair in conn.list_key_pairs():
         print(keypair)
@@ -132,9 +148,10 @@ def main():
 
     # destroy running demo instances
     for instance in conn.list_nodes():
-        if instance.name in ['all-in-one', 'app-worker-1', 'app-worker-2', 'app-worker-3', 'app-controller',
+        if instance.name in ['all-in-one', 'app-worker-1', 'app-worker-2',
+                             'app-worker-3', 'app-controller',
                              'app-services', 'app-api-1', 'app-api-2']:
-            print(('Destroying Instance: %s' % instance.name))
+            print(f'Destroying Instance: ${instance.name}')
             conn.destroy_node(instance)
 
     # wait until all nodes are destroyed to be able to remove depended security groups
@@ -152,7 +169,7 @@ def main():
     # delete security groups
     for group in conn.ex_list_security_groups():
         if group.name in ['control', 'worker', 'api', 'services']:
-            print(('Deleting security group: %s' % group.name))
+            print(f'Deleting security group: ${group.name}')
             conn.ex_delete_security_group(group)
 
     ###########################################################################
@@ -166,7 +183,8 @@ def main():
         print(('Checking for existing ' + security_group_name + ' security group...'))
         for security_grp in connection.ex_list_security_groups():
             if security_grp.name == security_group_name:
-                print(('Security Group ' + security_group_name + ' already exists. Skipping creation.'))
+                print(('Security Group ' + security_group_name +
+                       ' already exists. Skipping creation.'))
                 return worker_security_group
         return False
 
@@ -178,20 +196,23 @@ def main():
         api_security_group = get_security_group(conn, "api")
 
     if not get_security_group(conn, "worker"):
-        worker_security_group = conn.ex_create_security_group('worker', 'for services that run on a worker node')
+        worker_security_group = conn.ex_create_security_group(
+            'worker', 'for services that run on a worker node')
         conn.ex_create_security_group_rule(worker_security_group, 'TCP', 22, 22)
     else:
         worker_security_group = get_security_group(conn, "worker")
 
     if not get_security_group(conn, "control"):
-        controller_security_group = conn.ex_create_security_group('control', 'for services that run on a control node')
+        controller_security_group = conn.ex_create_security_group(
+            'control', 'for services that run on a control node')
         conn.ex_create_security_group_rule(controller_security_group, 'TCP', 22, 22)
         conn.ex_create_security_group_rule(controller_security_group, 'TCP', 80, 80)
         conn.ex_create_security_group_rule(controller_security_group, 'TCP', 5672, 5672,
                                            source_security_group=worker_security_group)
 
     if not get_security_group(conn, "services"):
-        services_security_group = conn.ex_create_security_group('services', 'for DB and AMQP services only')
+        services_security_group = conn.ex_create_security_group(
+            'services', 'for DB and AMQP services only')
         conn.ex_create_security_group_rule(services_security_group, 'TCP', 22, 22)
         conn.ex_create_security_group_rule(services_security_group, 'TCP', 3306, 3306,
                                            source_security_group=api_security_group)
@@ -229,24 +250,18 @@ def main():
     #
     ###########################################################################
 
-    #hsfd_faafo_cloud_init_script = 'https://gogs.informatik.hs-fulda.de/srieger/cloud-computing-msc-ai-examples/raw/master/faafo/contrib/install.sh'
-    # testing / faafo dev branch:
-    hsfd_faafo_cloud_init_script = 'https://gogs.informatik.hs-fulda.de/srieger/cloud-computing-msc-ai-examples/raw/branch/dev_faafo/faafo/contrib/install.sh'
-
-    userdata_service = '''#!/usr/bin/env bash
-    curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
-        -i database -i messaging
-    rabbitmqctl add_user faafo guest
-    rabbitmqctl set_user_tags faafo administrator
-    rabbitmqctl set_permissions -p / faafo ".*" ".*" ".*"
-    '''
+    userdata_service = '#!/usr/bin/env bash\n' \
+               'curl -L -s https://gogs.informatik.hs-fulda.de/srieger/cloud-computing-msc-ai-' \
+               'examples/raw/master/faafo/contrib/install.sh | bash -s -- ' \
+               '-i database -i messaging\n'
+    print('\nUsing cloud-init userdata for service:\n"' + userdata_service + '"\n')
 
     print('Starting new app-services instance and wait until it is running...')
     instance_services = conn.create_node(name='app-services',
                                          image=image,
                                          size=flavor,
                                          networks=[network],
-                                         ex_keyname=keypair_name,
+                                         ex_keyname=KEYPAIR_NAME,
                                          ex_userdata=userdata_service,
                                          ex_security_groups=[services_security_group])
     instance_services = conn.wait_until_running(nodes=[instance_services], timeout=120,
@@ -259,18 +274,20 @@ def main():
     #
     ###########################################################################
 
-    userdata_api = '''#!/usr/bin/env bash
-    curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
-        -i faafo -r api -m 'amqp://faafo:guest@%(services_ip)s:5672/' \
-        -d 'mysql+pymysql://faafo:password@%(services_ip)s:3306/faafo'
-    ''' % {'services_ip': services_ip}
+    userdata_api = '#!/usr/bin/env bash\n' \
+                   'curl -L -s https://gogs.informatik.hs-fulda.de/srieger/' \
+                   'cloud-computing-msc-ai-examples/raw/master/faafo/contrib/' \
+                   'install.sh | bash -s -- ' \
+                   f'-i faafo -r api -m "amqp://faafo:guest@{services_ip}:5672/" ' \
+                   f'-d "mysql+pymysql://faafo:password@{services_ip}:3306/faafo"'
+    print('\nUsing cloud-init userdata for api:\n"' + userdata_api + '"\n')
 
     print('Starting new app-api-1 instance and wait until it is running...')
     instance_api_1 = conn.create_node(name='app-api-1',
                                       image=image,
                                       size=flavor,
                                       networks=[network],
-                                      ex_keyname=keypair_name,
+                                      ex_keyname=KEYPAIR_NAME,
                                       ex_userdata=userdata_api,
                                       ex_security_groups=[api_security_group])
 
@@ -279,7 +296,7 @@ def main():
                                       image=image,
                                       size=flavor,
                                       networks=[network],
-                                      ex_keyname=keypair_name,
+                                      ex_keyname=KEYPAIR_NAME,
                                       ex_userdata=userdata_api,
                                       ex_security_groups=[api_security_group])
 
@@ -293,7 +310,8 @@ def main():
     for instance in [instance_api_1, instance_api_2]:
         floating_ip = get_floating_ip(conn)
         conn.ex_attach_floating_ip_to_node(instance, floating_ip)
-        print(('allocated %(ip)s to %(host)s' % {'ip': floating_ip.ip_address, 'host': instance.name}))
+        print(('allocated %(ip)s to %(host)s' % {'ip': floating_ip.ip_address,
+                                                 'host': instance.name}))
 
     ###########################################################################
     #
@@ -301,10 +319,14 @@ def main():
     #
     ###########################################################################
 
-    userdata_worker = '''#!/usr/bin/env bash
-    curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
-        -i faafo -r worker -e 'http://%(api_1_ip)s' -m 'amqp://faafo:guest@%(services_ip)s:5672/'
-    ''' % {'api_1_ip': api_1_ip, 'services_ip': services_ip}
+    userdata_worker = '#!/usr/bin/env bash\n' \
+                      'curl -L -s https://gogs.informatik.hs-fulda.de/srieger/' \
+                      'cloud-computing-msc-ai-examples/raw/master/faafo/contrib/' \
+                      'install.sh | bash -s -- ' \
+                      f'-i faafo -r worker -e "http://{api_1_ip}" '\
+                      f'-m "amqp://faafo:guest@{services_ip}:5672/"'
+    print('\nUsing cloud-init userdata for worker:\n"' + userdata_worker + '"\n')
+
 
     # userdata_api-api-2 = '''#!/usr/bin/env bash
     # curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
@@ -315,7 +337,7 @@ def main():
     instance_worker_1 = conn.create_node(name='app-worker-1',
                                          image=image, size=flavor,
                                          networks=[network],
-                                         ex_keyname=keypair_name,
+                                         ex_keyname=KEYPAIR_NAME,
                                          ex_userdata=userdata_worker,
                                          ex_security_groups=[worker_security_group])
 
@@ -323,12 +345,12 @@ def main():
     instance_worker_2 = conn.create_node(name='app-worker-2',
                                          image=image, size=flavor,
                                          networks=[network],
-                                         ex_keyname=keypair_name,
+                                         ex_keyname=KEYPAIR_NAME,
                                          ex_userdata=userdata_worker,
                                          ex_security_groups=[worker_security_group])
 
     # do not start worker 3 initially, can be started using scale-out-add-worker.py demo
-    
+
     #print('Starting new app-worker-3 instance and wait until it is running...')
     #instance_worker_3 = conn.create_node(name='app-worker-3',
     #                                     image=image, size=flavor,

demo4-scale-out-add-worker.py → demo4_scale_out_add_worker.py

@@ -1,54 +1,71 @@
+"""Example for Cloud Computing Course Master AI / GSD"""
+
+# This script demonstrates how to use libcloud to start an instance in an OpenStack environment.
+# The script will add an additional worker to a running faafo example application
+
+# Needed if the password should be prompted for:
 # import getpass
-# import os
-# import libcloud.security
+import os
+import sys
+# import time
 
-import time
 from libcloud.compute.providers import get_driver
 from libcloud.compute.types import Provider
 
-# reqs:
-#   services: nova, glance, neutron
-#   resources: 2 instances (m1.small), 2 floating ips (1 keypair, 2 security groups)
+# For our new Charmed OpenStack private cloud, we need to specify the path to the root
+# CA certificate
+import libcloud.security
+libcloud.security.CA_CERTS_PATH = ['./root-ca.crt']
+# Disable SSL certificate verification (not recommended for production)
+# libcloud.security.VERIFY_SSL_CERT = False
 
-# Please use 1-29 for X in the following variable to specify your group number. (will be used for the username,
-# project etc., as coordinated in the lab sessions)
+# Please use 1-29 as environment variable GROUP_NUMBER to specify your group number.
+# (will be used for the username, project etc., as coordinated in the lab sessions)
 
-group_number = X
+group_number = os.environ.get('GROUP_NUMBER')
+if group_number is None:
+    sys.exit('Please set the GROUP_NUMBER environment variable to your group number,\n'
+             'e.g., on Windows:\n'
+             '  "$env:GROUP_NUMBER=0" or "set GROUP_NUMBER=0"\n'
+             'or on Linux/MacOS:\n'
+             '  "export GROUP_NUMBER=0" or "set GROUP_NUMBER=0"')
 
 
 # web service endpoint of the private cloud infrastructure
-auth_url = 'https://private-cloud.informatik.hs-fulda.de:5000'
+# auth_url = 'https://private-cloud.informatik.hs-fulda.de:5000'
+AUTH_URL = 'https://10.32.4.182:5000'
+# auth_url = 'https://private-cloud2.informatik.hs-fulda.de:5000'
 # your username in OpenStack
-auth_username = 'CloudComp' + str(group_number)
+AUTH_USERNAME = 'CloudComp' + str(group_number)
+print(f'Using username: {AUTH_USERNAME}\n')
 # your project in OpenStack
-project_name = 'CloudComp' + str(group_number)
+PROJECT_NAME = 'CloudComp' + str(group_number)
 # A network in the project the started instance will be attached to
-project_network = 'CloudComp' + str(group_number) + '-net'
+PROJECT_NETWORK = 'CloudComp' + str(group_number) + '-net'
 
 # The image to look for and use for the started instance
-#ubuntu_image_name = "Ubuntu 20.04 - Focal Fossa - 64-bit - Cloud Based Image"
+# ubuntu_image_name = "Ubuntu 18.04 - Bionic Beaver - 64-bit - Cloud Based Image"
 #UBUNTU_IMAGE_NAME = "auto-sync/ubuntu-jammy-22.04-amd64-server-20240319-disk1.img"
 UBUNTU_IMAGE_NAME = "ubuntu-22.04-jammy-x86_64"
 
-# The public key to be used for SSH connection, please make sure, that you have the corresponding private key
+# The public key to be used for SSH connection, please make sure, that you have the
+# corresponding private key
 #
 # id_rsa.pub should look like this (standard sshd pubkey format):
 # ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAw+J...F3w2mleybgT1w== user@HOSTNAME
+KEYPAIR_NAME = 'srieger-pub'
+PUB_KEY_FILE = '~/.ssh/id_rsa.pub'
 
-#keypair_name = 'CloudComp30-keypair'
-keypair_name = "srieger-pub"
-pub_key_file = '~/.ssh/id_rsa.pub'
-
-flavor_name = 'm1.small'
+FLAVOR_NAME = 'm1.small'
 
 
 # default region
-region_name = 'RegionOne'
-# domain to use, "default" for local accounts, "hsfulda" for RZ LDAP, e.g., using fdaiXXXX as auth_username
-domain_name = "default"
+REGION_NAME = 'RegionOne'
+# domain to use, "default" for local accounts, formerly "hsfulda" for LDAP accounts etc.
+# domain_name = "default"
 
 
-def main():
+def main():  # noqa: C901 pylint: disable=too-many-branches,too-many-statements,too-many-locals,missing-function-docstring
     ###########################################################################
     #
     # get credentials
@@ -67,16 +84,14 @@ def main():
     #
     ###########################################################################
 
-    # libcloud.security.VERIFY_SSL_CERT = False
-
     provider = get_driver(Provider.OPENSTACK)
-    conn = provider(auth_username,
+    conn = provider(AUTH_USERNAME,
                     auth_password,
-                    ex_force_auth_url=auth_url,
+                    ex_force_auth_url=AUTH_URL,
                     ex_force_auth_version='3.x_password',
-                    ex_tenant_name=project_name,
-                    ex_force_service_region=region_name,
-                    ex_domain_name=domain_name)
+                    ex_tenant_name=PROJECT_NAME,
+                    ex_force_service_region=REGION_NAME)
+    #               ex_domain_name=domain_name)
 
     ###########################################################################
     #
@@ -87,25 +102,25 @@ def main():
     images = conn.list_images()
     image = ''
     for img in images:
-        if img.name == ubuntu_image_name:
+        if img.name == UBUNTU_IMAGE_NAME:
             image = img
 
     flavors = conn.list_sizes()
     flavor = ''
     for flav in flavors:
-        if flav.name == flavor_name:
+        if flav.name == FLAVOR_NAME:
             flavor = conn.ex_get_size(flav.id)
 
     networks = conn.ex_list_networks()
     network = ''
     for net in networks:
-        if net.name == project_network:
+        if net.name == PROJECT_NETWORK:
             network = net
 
     ###########################################################################
     #
     # get fixed a ip for service and api instance
-    # (better would be shared IP for the cluster etc.) 
+    # (better would be shared IP for the cluster etc.)
     #
     ###########################################################################
 
@@ -113,10 +128,11 @@ def main():
     for instance in conn.list_nodes():
         if instance.name == 'app-services':
             services_ip = instance.private_ips[0]
-            print(('Found app-services fixed IP to be: ', services_ip)) 
+            print(('Found app-services fixed IP to be: ', services_ip))
         if instance.name == 'app-api-1':
             api_1_ip = instance.private_ips[0]
-            print(('Found app-api-1 fixed IP to be: ', api_1_ip)) 
+            print(('Found app-api-1 fixed IP to be: ', api_1_ip))
+
 
     ###########################################################################
     #
@@ -127,18 +143,19 @@ def main():
     print('Checking for existing SSH key pair...')
     keypair_exists = False
     for keypair in conn.list_key_pairs():
-        if keypair.name == keypair_name:
+        if keypair.name == KEYPAIR_NAME:
             keypair_exists = True
 
     if keypair_exists:
-        print(('Keypair ' + keypair_name + ' already exists. Skipping import.'))
+        print(('Keypair ' + KEYPAIR_NAME + ' already exists. Skipping import.'))
     else:
         print('adding keypair...')
-        conn.import_key_pair_from_file(keypair_name, pub_key_file)
+        conn.import_key_pair_from_file(KEYPAIR_NAME, PUB_KEY_FILE)
 
     for keypair in conn.list_key_pairs():
         print(keypair)
-    
+
+
     ###########################################################################
     #
     # create security group dependency
@@ -150,33 +167,35 @@ def main():
         print(('Checking for existing ' + security_group_name + ' security group...'))
         for security_grp in connection.ex_list_security_groups():
             if security_grp.name == security_group_name:
-                print(('Security Group ' + security_group_name + ' already exists. Skipping creation.'))
+                print(('Security Group ' + security_group_name +
+                       ' already exists. Skipping creation.'))
                 return security_grp
         return False
 
     if not get_security_group(conn, "worker"):
-        worker_security_group = conn.ex_create_security_group('worker', 'for services that run on a worker node')
+        worker_security_group = conn.ex_create_security_group(
+            'worker', 'for services that run on a worker node')
         conn.ex_create_security_group_rule(worker_security_group, 'TCP', 22, 22)
     else:
         worker_security_group = get_security_group(conn, "worker")
 
     for security_group in conn.ex_list_security_groups():
         print(security_group)
-        
+
+
     ###########################################################################
     #
     # create worker instances
     #
     ###########################################################################
 
-    #hsfd_faafo_cloud_init_script = 'https://gogs.informatik.hs-fulda.de/srieger/cloud-computing-msc-ai-examples/raw/master/faafo/contrib/install.sh'
-    # testing / faafo dev branch:
-    hsfd_faafo_cloud_init_script = 'https://gogs.informatik.hs-fulda.de/srieger/cloud-computing-msc-ai-examples/raw/branch/dev_faafo/faafo/contrib/install.sh'
-
-    userdata_worker = '''#!/usr/bin/env bash
-    curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
-        -i faafo -r worker -e 'http://%(api_1_ip)s' -m 'amqp://faafo:guest@%(services_ip)s:5672/'
-    ''' % {'api_1_ip': api_1_ip, 'services_ip': services_ip}
+    userdata_worker = '#!/usr/bin/env bash\n' \
+                      'curl -L -s https://gogs.informatik.hs-fulda.de/srieger/' \
+                      'cloud-computing-msc-ai-examples/raw/master/faafo/contrib/' \
+                      'install.sh | bash -s -- ' \
+                      f'-i faafo -r worker -e "http://{api_1_ip}" '\
+                      f'-m "amqp://faafo:guest@{services_ip}:5672/"'
+    print('\nUsing cloud-init userdata for worker:\n"' + userdata_worker + '"\n')
 
     # userdata-api-2 = '''#!/usr/bin/env bash
     # curl -L -s ''' + hsfd_faafo_cloud_init_script + ''' | bash -s -- \
@@ -187,7 +206,7 @@ def main():
     instance_worker_3 = conn.create_node(name='app-worker-3',
                                          image=image, size=flavor,
                                          networks=[network],
-                                         ex_keyname=keypair_name,
+                                         ex_keyname=KEYPAIR_NAME,
                                          ex_userdata=userdata_worker,
                                          ex_security_groups=[worker_security_group])