docs/loadbalancer/drivers/elb.rst - libcloud - Git at Google

 Elastic Load Balancing interface for AWS
 ========================================

 What is Elastic Load Balancing?
 -------------------------------

 Amazon Web Services (AWS) provides Elastic Load Balancing to automatically
 distribute incoming web traffic across multiple Amazon Elastic Compute Cloud
 (Amazon EC2) instances. With Elastic Load Balancing, you can add and remove
 EC2 instances as your needs change without disrupting the overall flow of
 information. If one EC2 instance fails, Elastic Load Balancing automatically
 reroutes the traffic to the remaining running EC2 instances. If the failed
 EC2 instance is restored, Elastic Load Balancing restores the traffic to
 that instance. Elastic Load Balancing offers clients a single point of
 contact, and it can also serve as the first line of defense against attacks
 on your network. You can offload the work of encryption and decryption to
 Elastic Load Balancing, so your servers can focus on their main task.


 Ok Now Tell me some advantages of using Elastic Load Balancing
 ---------------------------------------------------------------

 * Distribution of requests to Amazon EC2 instances (servers)in multiple
   vailability Zones so that the risk of overloading one single instance
   is minimized.
 * Continuous monitoring of the health of Amazon EC2 instances registered
   with the load balancer.
 * Support for end-to-end traffic encryption on those networks that use
   secure (HTTPS/SSL) connections.
 * Support for the sticky session feature, which is the ability to "stick"
   user sessions to specific Amazon EC2 instances.
 * Association of the load balancer with your domain name.
 * Supports use of both the Internet Protocol version 4 (IPv4) and
   Internet Protocol version 6 (IPv6).

 "How it works?" would be nice to share
 --------------------------------------

 Elastic Load Balancing consists of two components: the load balancers and
 the controller service. The load balancers monitor the traffic and handle
 requests that come in through the Internet. The controller service monitors
 the load balancers, adding and removing load balancers as needed and
 verifying that the load balancers are functioning properly.

 * The client sends a URL request to DNS servers to access your application.
   For example, myLB-1234567890.us-east-1.elb.amazonaws.com.
 * Then The client looks for the resolution of the DNS name sent by the
   DNS server.
 * The client then opens a connection to the machine at the provided IP address.
   The instance at this address is the load balancer you created.
 * The load balancer checks the health states of all the registered EC2 application
   instances within the selected Availability Zones
 * Then load balancer routes the client request to the healthy EC2 application
   instance identified in the previous step.

 That's not enough, you want to learn more about ELB, then Refer `AWS site
 <http://docs.aws.amazon.com/ElasticLoadBalancing/latest/APIReference/Welcome.html/>`_.


 Now lets dive into the tutorial which will focus on libcloud Elastic
 Load Balancing interface for AWS.

 1. Creating a Connection
 -------------------------

 The first step in accessing ELB is to create a connection to the service.

 So, when you instantiate an ELB driver you need to pass the following arguments
 to the driver constructor:

 * ``key`` - Your AWS API key
 * ``secret`` - Your AWS secret key
 * ``region`` - The region of your AWS instance host point
   (e.g ``us-west-2`` for ``US West (Oregon) Region``)

 Typically this will lead to:

 .. literalinclude:: /examples/loadbalancer/elb/create_lb_connection_for_aws.py
    :language: python

 if everything gone well; means if your console has not yelled any error then
 your connection has been established.

 by the way if you have difficulty in getting your 'access key' and 'secret key'
 id's, look at security credentials page of AWS management console.


 The base `libcloud` ELB API allows you to:

 * list, create, attach, detach, delete load balancer
 * list protocols related to load balancer

 Non-standard functionality and extension methods
 -------------------------------------------------

 The AWS ELB driver exposes a lot of `libcloud` non-standard
 functionalities through extension methods and arguments.

 These functionalities include:

 * list laod balancer policy
 * list load balancer policy types
 * create, delete load balancer policy
 * create listeners for load balancer
 * enable/disable policies on backend server & listeners

 2. Getting Existing Load Balancers
 -----------------------------------

 To retrieve any exiting load balancers available

 .. literalinclude:: /examples/loadbalancer/elb/list_load_balancer.py
    :language: python

 this will return you a list of load balancers
 ``[<LoadBalancer: id=balancer_id, name=balancer_name, state=balancer_state>]``

 3. Creating New Load Balancers
 -------------------------------

 To create new load balancer initialise some members for the load balancer
 first

 .. literalinclude:: /examples/loadbalancer/elb/create_load_balancer.py
    :language: python

 Ok if everything is fine; you will see this on your python shell screen
 ``[<LoadBalancer: id='MyLB', name='MyLB', state=1]``

 note: ``state`` value may differ

 4. Creating Load Balancer Policy
 --------------------------------

 To creates a new policy for a load balancer that contains the necessary
 attributes depending on the policy type

 .. literalinclude:: /examples/loadbalancer/elb/create_lb_policy.py
    :language: python

 If you get ``True``, then congratulation you have successfully created
 the load balancer policy.

 Now there are some extension methods to look on
 To get all policy associated with the load balancer

 .. literalinclude:: /examples/loadbalancer/elb/ex_list_balancer_policies.py
    :language: python

 you will get output something like this
  ``['EnableProxyProtocol']``

 To get all the policy types available

 .. literalinclude:: /examples/loadbalancer/elb/ex_list_balancer_policy_types.py
    :language: python

 It will return a list of available policy types
  ``['EnableProxyProtocolType']``

 To delete a policy associated with the load balancer

 .. literalinclude:: /examples/loadbalancer/elb/ex_delete_balancer_policy.py
    :language: python

 Will return ``True`` if it deletes the policy successfully.

 5. Enable/Disable Policy on Backend server
 -------------------------------------------

 Wait! first tell me about Policies
 ----------------------------------

 A security policy is a combination of SSL Protocols, SSL Ciphers, and
 the Server Order Preference option. For more information about
 configuring SSL connection for your load balancer

 Two Types

 * Predefined Security Policy—A list of predefined SSL negotiation
   configurations with enabled ciphers and protocols
 * Custom Security Policy—A list of ciphers and protocols that you
   specify to create a custom negotiation configuration

 To enable the policies on the server we need to call
 "SetLoadBalancerPoliciesForBackendServer" action.

 .. literalinclude:: /examples/loadbalancer/elb/ex_set_balancer_policies_backend_server.py
    :language: python

 Will return ``True`` if it sets the policies successfully on backend server.

 To disable the policy you just need to pass the policies parameter as empty
 list

 6. Enable/Diable Policy on Listeners
 -------------------------------------

 I don't have any idea about ``listeners``?
 ------------------------------------------

 A listener is a process that listens for connection requests.
 It is configured with a protocol and a port number for front-end
 (client to load balancer) and back-end (load balancer to back-end instance)
 connections.

 Elastic Load Balancing supports the load balancing of applications
 using HTTP, HTTPS (secure HTTP), TCP, and SSL (secure TCP) protocols.
 The HTTPS uses the SSL protocol to establish secure connections over
 the HTTP layer. You can also use SSL protocol to establish secure
 connections over the TCP layer.

 To create one or more listeners on a load balancer for the specified port

 .. literalinclude:: /examples/loadbalancer/elb/ex_create_balancer_listeners.py
    :language: python

 Will return ``True`` if it creates load balancer listeners successfully.

 As mentioned above for backend Server, to enable the policies on the listeners,
 need to call ``SetLoadBalancerPoliciesOfListener`` action

 .. literalinclude:: /examples/loadbalancer/elb/ex_set_balancer_policies_listener.py
    :language: python

 Will return ``True`` if it sets load balancer policies for listeners successfully.

 To disable the policy you just need to pass the policies parameter as empty
 list

 Wrapping up
 -----------

 So now we have come to the end of tutorial. This last program file implements all
 the above attributes of ELB driver that we have discussed.

 .. literalinclude:: /examples/loadbalancer/elb/complete_tut.py
    :language: python
	Elastic Load Balancing interface for AWS
	========================================

	What is Elastic Load Balancing?
	-------------------------------

	Amazon Web Services (AWS) provides Elastic Load Balancing to automatically
	distribute incoming web traffic across multiple Amazon Elastic Compute Cloud
	(Amazon EC2) instances. With Elastic Load Balancing, you can add and remove
	EC2 instances as your needs change without disrupting the overall flow of
	information. If one EC2 instance fails, Elastic Load Balancing automatically
	reroutes the traffic to the remaining running EC2 instances. If the failed
	EC2 instance is restored, Elastic Load Balancing restores the traffic to
	that instance. Elastic Load Balancing offers clients a single point of
	contact, and it can also serve as the first line of defense against attacks
	on your network. You can offload the work of encryption and decryption to
	Elastic Load Balancing, so your servers can focus on their main task.


	Ok Now Tell me some advantages of using Elastic Load Balancing
	---------------------------------------------------------------

	* Distribution of requests to Amazon EC2 instances (servers)in multiple
	vailability Zones so that the risk of overloading one single instance
	is minimized.
	* Continuous monitoring of the health of Amazon EC2 instances registered
	with the load balancer.
	* Support for end-to-end traffic encryption on those networks that use
	secure (HTTPS/SSL) connections.
	* Support for the sticky session feature, which is the ability to "stick"
	user sessions to specific Amazon EC2 instances.
	* Association of the load balancer with your domain name.
	* Supports use of both the Internet Protocol version 4 (IPv4) and
	Internet Protocol version 6 (IPv6).

	"How it works?" would be nice to share
	--------------------------------------

	Elastic Load Balancing consists of two components: the load balancers and
	the controller service. The load balancers monitor the traffic and handle
	requests that come in through the Internet. The controller service monitors
	the load balancers, adding and removing load balancers as needed and
	verifying that the load balancers are functioning properly.

	* The client sends a URL request to DNS servers to access your application.
	For example, myLB-1234567890.us-east-1.elb.amazonaws.com.
	* Then The client looks for the resolution of the DNS name sent by the
	DNS server.
	* The client then opens a connection to the machine at the provided IP address.
	The instance at this address is the load balancer you created.
	* The load balancer checks the health states of all the registered EC2 application
	instances within the selected Availability Zones
	* Then load balancer routes the client request to the healthy EC2 application
	instance identified in the previous step.

	That's not enough, you want to learn more about ELB, then Refer `AWS site
	<http://docs.aws.amazon.com/ElasticLoadBalancing/latest/APIReference/Welcome.html/>`_.


	Now lets dive into the tutorial which will focus on libcloud Elastic
	Load Balancing interface for AWS.

	1. Creating a Connection
	-------------------------

	The first step in accessing ELB is to create a connection to the service.

	So, when you instantiate an ELB driver you need to pass the following arguments
	to the driver constructor:

	* ``key`` - Your AWS API key
	* ``secret`` - Your AWS secret key
	* ``region`` - The region of your AWS instance host point
	(e.g ``us-west-2`` for ``US West (Oregon) Region``)

	Typically this will lead to:

	.. literalinclude:: /examples/loadbalancer/elb/create_lb_connection_for_aws.py
	:language: python

	if everything gone well; means if your console has not yelled any error then
	your connection has been established.

	by the way if you have difficulty in getting your 'access key' and 'secret key'
	id's, look at security credentials page of AWS management console.


	The base `libcloud` ELB API allows you to:

	* list, create, attach, detach, delete load balancer
	* list protocols related to load balancer

	Non-standard functionality and extension methods
	-------------------------------------------------

	The AWS ELB driver exposes a lot of `libcloud` non-standard
	functionalities through extension methods and arguments.

	These functionalities include:

	* list laod balancer policy
	* list load balancer policy types
	* create, delete load balancer policy
	* create listeners for load balancer
	* enable/disable policies on backend server & listeners

	2. Getting Existing Load Balancers
	-----------------------------------

	To retrieve any exiting load balancers available

	.. literalinclude:: /examples/loadbalancer/elb/list_load_balancer.py
	:language: python

	this will return you a list of load balancers
	``[<LoadBalancer: id=balancer_id, name=balancer_name, state=balancer_state>]``

	3. Creating New Load Balancers
	-------------------------------

	To create new load balancer initialise some members for the load balancer
	first

	.. literalinclude:: /examples/loadbalancer/elb/create_load_balancer.py
	:language: python

	Ok if everything is fine; you will see this on your python shell screen
	``[<LoadBalancer: id='MyLB', name='MyLB', state=1]``

	note: ``state`` value may differ

	4. Creating Load Balancer Policy
	--------------------------------

	To creates a new policy for a load balancer that contains the necessary
	attributes depending on the policy type

	.. literalinclude:: /examples/loadbalancer/elb/create_lb_policy.py
	:language: python

	If you get ``True``, then congratulation you have successfully created
	the load balancer policy.

	Now there are some extension methods to look on
	To get all policy associated with the load balancer

	.. literalinclude:: /examples/loadbalancer/elb/ex_list_balancer_policies.py
	:language: python

	you will get output something like this
	``['EnableProxyProtocol']``

	To get all the policy types available

	.. literalinclude:: /examples/loadbalancer/elb/ex_list_balancer_policy_types.py
	:language: python

	It will return a list of available policy types
	``['EnableProxyProtocolType']``

	To delete a policy associated with the load balancer

	.. literalinclude:: /examples/loadbalancer/elb/ex_delete_balancer_policy.py
	:language: python

	Will return ``True`` if it deletes the policy successfully.

	5. Enable/Disable Policy on Backend server
	-------------------------------------------

	Wait! first tell me about Policies
	----------------------------------

	A security policy is a combination of SSL Protocols, SSL Ciphers, and
	the Server Order Preference option. For more information about
	configuring SSL connection for your load balancer

	Two Types

	* Predefined Security Policy—A list of predefined SSL negotiation
	configurations with enabled ciphers and protocols
	* Custom Security Policy—A list of ciphers and protocols that you
	specify to create a custom negotiation configuration

	To enable the policies on the server we need to call
	"SetLoadBalancerPoliciesForBackendServer" action.

	.. literalinclude:: /examples/loadbalancer/elb/ex_set_balancer_policies_backend_server.py
	:language: python

	Will return ``True`` if it sets the policies successfully on backend server.

	To disable the policy you just need to pass the policies parameter as empty
	list

	6. Enable/Diable Policy on Listeners
	-------------------------------------

	I don't have any idea about ``listeners``?
	------------------------------------------

	A listener is a process that listens for connection requests.
	It is configured with a protocol and a port number for front-end
	(client to load balancer) and back-end (load balancer to back-end instance)
	connections.

	Elastic Load Balancing supports the load balancing of applications
	using HTTP, HTTPS (secure HTTP), TCP, and SSL (secure TCP) protocols.
	The HTTPS uses the SSL protocol to establish secure connections over
	the HTTP layer. You can also use SSL protocol to establish secure
	connections over the TCP layer.

	To create one or more listeners on a load balancer for the specified port

	.. literalinclude:: /examples/loadbalancer/elb/ex_create_balancer_listeners.py
	:language: python

	Will return ``True`` if it creates load balancer listeners successfully.

	As mentioned above for backend Server, to enable the policies on the listeners,
	need to call ``SetLoadBalancerPoliciesOfListener`` action

	.. literalinclude:: /examples/loadbalancer/elb/ex_set_balancer_policies_listener.py
	:language: python

	Will return ``True`` if it sets load balancer policies for listeners successfully.

	To disable the policy you just need to pass the policies parameter as empty
	list

	Wrapping up
	-----------

	So now we have come to the end of tutorial. This last program file implements all
	the above attributes of ELB driver that we have discussed.

	.. literalinclude:: /examples/loadbalancer/elb/complete_tut.py
	:language: python