Policy Composition

Principles and Practice

Jason M. Coposky

@jason_coposky

Executive Director, iRODS Consortium

Policy Composition

Principles and Practice

February 19, 2020

Renaissance Computing Institute

UNC-Chapel Hill

Our Membership

Consortium

Member

Consortium

Member

What is Data Management

A Definition of Data Management

 

 

"The development, execution and supervision of plans, policies, programs, and practices that control, protect, deliver, and enhance the value of data and information assets."

 

 

Organizations need a future-proof solution to managing data and its surrounding infrastructure

What is a Policy

A Definition of Policy

 

 

A set of ideas or a plan of what to do in particular situations that has been agreed to officially by a group of people...

 

 

So how does iRODS do this?

The iRODS Data Management Model

Core Competencies

Policy

Capabilities

Patterns

Starting at the bottom :: Core Competencies

The underlying iRODS technology in four areas:

iRODS Policies

The reflection of real world data management decisions in computer actionable code.

 

(a plan of what to do in particular situations)

Possible Policies

  • Data Movement
  • Data Verification
  • Data Retention
  • Data Replication
  • Data Placement
  • Checksum Validation
  • Metadata Extraction
  • Metadata Application
  • Metadata Conformance
  • Replica Verification
  • Vault to Catalog Verification
  • Catalog to Vault Verification
  • ...

Policy Composition

Consider policy as building blocks towards capabilities

Follow proven software engineering principles:

    Favor composition over monolithic implementations

Rules and Dynamic Policy Enforcement Points can be overloaded and fall through

Implement or configure several rule bases or rule engine plugins to achieve complex use cases

The Original Approach

Assuming there was a policy enforcement point for the desired event...

acPostProcForPut() { 
  if($rescName == "demoResc") {
      # extract and apply metadata
  }
  else if($rescName == "cacheResc") {
      # async replication to archive
  }
  else if($objPath like "/tempZone/home/alice/*" &&
          $rescName == "indexResc") {
      # launch an indexing job
  }
  else if(xyz) {
      # compute checksums ...        
  }
  
  # and so on ...
}

In /etc/irods/core.re ...

Policy Composition across rule bases

For example: pep_data_obj_put_post(...)

  • Metadata extraction and application
  • Asynchronous Replication
  • Initiate Indexing
  • Apply access time metadata
  • Asynchronous checksum computation

Rather than one monolithic implementation, separate the implementations into individual rule bases, or plugins, and allow the rule(s) to fall through

Policy Composition across rule bases

Separate the implementation into several rule bases:

pep_api_data_obj_put_post(*INSTANCE_NAME, *COMM, *DATAOBJINP, *BUFFER, *PORTAL_OPR_OUT) {
  # metadata extraction and application code
  
  RULE_ENGINE_CONTINUE
}

/etc/irods/metadata.re

pep_api_data_obj_put_post(*INSTANCE_NAME, *COMM, *DATAOBJINP, *BUFFER, *PORTAL_OPR_OUT) {
  # checksum code
  
  RULE_ENGINE_CONTINUE
}

/etc/irods/checksum.re

pep_api_data_obj_put_post(*INSTANCE_NAME, *COMM, *DATAOBJINP, *BUFFER, *PORTAL_OPR_OUT) {
  # access time application code
  
  RULE_ENGINE_CONTINUE
}

/etc/irods/access_time.re

Policy Composition across rule bases

Within the Rule Engine Plugin Framework, order matters

        "rule_engines": [
            {
                "instance_name": "irods_rule_engine_plugin-irods_rule_language-instance",
                "plugin_name": "irods_rule_engine_plugin-irods_rule_language",
                "plugin_specific_configuration": {
                        ...
                        "re_rulebase_set": [
                            "metadata",
                            "checksum",
                            "access_time",
                            "core"
                        ],
                        ...
                },
                "shared_memory_instance" : "irods_rule_language_rule_engine"
            },
            {
                "instance_name": "irods_rule_engine_plugin-cpp_default_policy-instance",
                "plugin_name": "irods_rule_engine_plugin-cpp_default_policy",
                "plugin_specific_configuration": {
                }
            }
       ]

Policy Composition and Capabilities

For example - Storage Tiering

  • Data Access Time
  • Identifying Violating Objects
  • Data Replication
  • Data Verification
  • Data Retention

The storage tiering capability - implemented as a composition which delegates each requirement out to separate policies.

The Initial Approach

Policies composed by a monolithic framework plugin

delegated policy by naming convention:

  • irods_policy_access_time
  • irods_policy_data_movement
  • irods_policy_data_replication
  • irods_policy_data_verification
  • irods_policy_data_retention

Each policy may be overridden by another rule engine, or rule base to customize to future use cases or technologies

Each policy may also be reused and combined into new Capabilities

The New Approach

Continue to separate the concerns:

  • When : Which policy enforcement points
  • What  : The policy to be invoked
  • How   : Synchronous or Asynchronous

Write simple policy implementations

Each policy may now be reused in a generic fashion, favoring configuration over code.

  • Not tied to a Policy Enforcement Point
  • Do one thing well
  • How it is invoked is of no concern

The When

When - The Event Handler

When - The Event Handler

A Rule Engine Plugin for a specific Class of events

The Events are specific to the class of the handler

The handler then invokes policy based on its configuration

  • Data Object
  • Collection
  • Metadata
  • User
  • Resource

When - event_handler-data_object_modified

A Rule Engine Plugin for data creation and modification events

Policy invocation is configured as an array of json objects for any given combination of events

Unifies the POSIX and Object behaviors into a single place to configure policy

  • Create
  • Read
  • Replication
  • Unlink
  • Rename
  • Register

When - event_handler-data_object_modified

Example : Synchronous Invocation

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy"    : "irods_policy_access_time",
                        "configuration" : {
                        }
                    },
                    {   "pre_or_post_invocation" : ["pre"],
                        "events" : ["replication"],
                        "policy"    : "irods_policy_example_policy",
                        "configuration" : {
                        }
                    }                  
                ]
            }
        }

The What

What - Simple policy implementations

  • irods_policy_access_time
  • irods_policy_query_processor
  • irods_policy_data_movement
  • irods_policy_data_replication
  • irods_policy_data_verification
  • irods_policy_data_retention

The library will continue to grow, with a cookbook of usages

Basic policies that are leveraged across many deployments and capabilities:

What - Simple policy implementations

Standardized JSON interface : parameters, and configuration

irods_policy_example_policy_implementation(*parameters, *configuration) {
  
}

iRODS Rule Language

def irods_policy_example_policy_implementation(rule_args, callback, rei):
# Parameters    rule_args[1]
# Configuration rule_args[2]

Python Rule Language

Policy can also be implemented as fast and light C++ rule engine plugins

What - Simple policy implementations

Policy may be invoked using one of three different conventions:

Provided parameters will vary based on the class of event handler

Each policy defines its interface by contract

  • Direct Invocation : a JSON object
  • Query Processor  : an array of parameters
  • Event Handler      : a JSON object

What - Simple policy implementations

Direct Invocation : Parameters passed as a JSON object regardless of how it is invoked

my_rule() {
        irods_policy_access_time( "{\"object_path\" : \"/tempZone/home/rods/file0.txt\"}", "");
}
{
    "policy" : "irods_policy_execute_rule",
    "payload" : {
        "policy_to_invoke" : "irods_policy_storage_tiering",
        "parameters" : {
            "object_path" : "/tempZone/home/rods/file0.txt"
         },
         "configuration" : {
         }
    }
}

Parameters may also be configured statically

What - Simple policy implementations

Query Processor Invocation

{
        "policy" : "irods_policy_enqueue_rule",
        "delay_conditions" : "<PLUSET>1s</PLUSET>",
        "payload" : {
            "policy" : "irods_policy_execute_rule",
            "payload" : {
                "policy_to_invoke" : "irods_policy_query_processor",
                "parameters" : {
                    "query_string" : "SELECT COLL_NAME, DATA_NAME, RESC_NAME WHERE COLL_NAME like '/tempZone/home/rods%'",
                    "query_limit" : 10,
                    "query_type" : "general",
                    "number_of_threads" : 4,
                    "policy_to_invoke" : "irods_policy_engine_example"
                 }
             }
        }
}

For example the invoked policy would receive a row:

['/tempZone/home/rods/', 'file0.txt', 'demoResc']

Serializes results to JSON array and passed to the policy as the parameter string

What - Simple policy implementations

Event Handler Invocation

Serializes dataObjInp_t and rsComm_t to a JSON object

{
"comm":{
    "auth_scheme":"native","client_addr":"152.54.8.141","proxy_auth_info_auth_flag":"5","proxy_auth_info_auth_scheme":"",
    "proxy_auth_info_auth_str":"","proxy_auth_info_flag":"0","proxy_auth_info_host":"","proxy_auth_info_ppid":"0",
    "proxy_rods_zone":"tempZone","proxy_sys_uid":"0","proxy_user_name":"rods","proxy_user_other_info_user_comments":"",
    "proxy_user_other_info_user_create":"","proxy_user_other_info_user_info":"","proxy_user_other_info_user_modify":"",
    "proxy_user_type":"","user_auth_info_auth_flag":"5","user_auth_info_auth_scheme":"","user_auth_info_auth_str":"",
    "user_auth_info_flag":"0","user_auth_info_host":"","user_auth_info_ppid":"0","user_rods_zone":"tempZone",
    "user_sys_uid":"0","user_user_name":"rods","user_user_other_info_user_comments":"","user_user_other_info_user_create":"",
    "user_user_other_info_user_info":"","user_user_other_info_user_modify":"","user_user_type":""
    },
"cond_input":{
    "dataIncluded":"","dataType":"generic","destRescName":"ufs0","noOpenFlag":"","openType":"1",
    "recursiveOpr":"1", "resc_hier":"ufs0","selObjType":"dataObj","translatedPath":""
    },
"create_mode":"33204","data_size":"1","event":"CREATE","num_threads":"0",
"obj_path":"/tempZone/home/rods/test_put_gt_max_sql_rows/junk0083",
"offset":"0","open_flags":"2","opr_type":"1",
"policy_enforcement_point":"pep_api_data_obj_put_post"
}

Which is also passed in as the parameter string

What - Simple policy implementations

Configuration

{
    "policy" : "irods_policy_access_time",
    "configuration" : {
        "attribute" : "irods::access_time"
    }
}

Any additional statically set context passed into the policy

May be "plugin_specific_configuration" from a rule engine plugin or "configuration" from within the event framework

The How

How - Asynchronous Execution

{
    "policy" : "irods_policy_enqueue_rule",
    "delay_conditions" : "<EF>REPEAT FOR EVER</EF>",
    "payload" : {
        "policy" : "irods_policy_example",
        "configuration" : {
        }
    }
}
INPUT null
OUTPUT ruleExecOut

The cpp_default rule engine plugin in 4.2.8 will now

support two new policies:

  • irods_policy_enqueue_rule
  • irods_policy_execute_rule

The enqueue rule policy will push a job onto the delayed execution queue.  The "payload" object holds the rule which is to be executed.

How - Asynchronous Execution

The execute rule policy will invoke a policy engine either from the delayed execute queue or as a direct invocation

{
   "policy" : "irods_policy_execute_rule",
       "payload" : {
           "policy_to_invoke" : "irods_policy_example"
           "parameters" : {      
           },
           "configuration" : {           
           }
        }
    }
}
INPUT null
OUTPUT ruleExecOut

How - Asynchronous Execution

Sample Delayed Rule for Asynchronous Execution

{
        "policy" : "irods_policy_enqueue_rule",
        "delay_conditions" : "<EF>REPEAT FOR EVER</EF>",
        "payload" : {
            "policy" : "irods_policy_execute_rule",
            "payload" : {
                "policy_to_invoke" : "irods_policy_example"
                "parameters" : {
              
                 },
                 "configuration" : {
                   
                 }
             }
        }
}
INPUT null
OUTPUT ruleExecOut

Examples

Synchronous Access Time

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy"    : "irods_policy_access_time",
                        "configuration" : {
                        }
                    }                  
                ]
            }
        }

Synchronous Replication

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy"    : "irods_policy_data_replication",
                        "configuration" : {
                            "source_to_destination_map" : {
                                "source_resource_0" : ["destination_resource_0a", "destination_resource_0b"],
                                "source_resource_1" : ["destination_resource_1a"],
                            }
                        }
                    },
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy"    : "irods_policy_data_replication",
                        "configuration" : {
                            "destination_resource" : "destination_resource_3"
                            }
                        }
                    },                  
                ]
            }
        }

Asynchronous Replication

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy" : "irods_policy_enqueue_rule",
                        "delay_conditions" : "<ET>PLUSET 1</ET>",
                        "payload" : {
                            "policy" : "irods_policy_execute_rule",
                            "payload" : {
                                "policy_to_invoke" : "irods_policy_data_replication",
                                "configuration" : {
                                    "source_to_destination_map" : {
                                        "source_resource_0" : ["destination_resource_0a", "destination_resource_0b"],
                                        "source_resource_1" : ["destination_resource_1a"],
                                    }
                                }
                            }
                        }
                    }                  
                ]
            }
        }

Synchronous Retention

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["replication"],
                        "policy" : "irods_policy_data_retention",
                        "configuration" : {
                            "mode" : "trim_single_replica",
                            "source_resource_list" : ["source_resource_1", "source_resource_2"]
                        }
                    }                  
                ]
            }
        }

Query Driven Asynchronous Retention

        {
            "policy" : "irods_policy_enqueue_rule",
            "delay_conditions" : "<EF>REPEAT FOR EVER</EF>",
            "payload" : {
                "policy" : "irods_policy_execute_rule",
                "payload" : {
                    "policy_to_invoke" : "irods_policy_query_processor",
                    "parameters" : {
                        "query_string" : "SELECT USER_NAME, COLL_NAME, DATA_NAME, RESC_NAME WHERE
                                          COLL_NAME like '/tempZone/home/rods%' AND
                                          RESC_NAME IN ('source_resource_1', 'source_resource_2')",
                        "query_limit" : 10,
                        "query_type" : "general",
                        "number_of_threads" : 4,
                        "policy_to_invoke" : "irods_policy_data_retention",
                        "configuration" : {
                            "mode" : "trim_single_replica",
                            "source_resource_list" : ["source_resource_1", "source_resource_2"]
                        }
                    }
                }
            }
        }

Synchronous Verification

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registation"],
                        "policy" : "irods_policy_data_verification",
                        "configuration" : {
                            "attribute" : "irods::verification::type"
                        }
                    }                  
                ]
            }
        }

The type of verification to perform is stored as metadata on the resource:

  • catalog
  • filesystem
  • checksum

Asynchronous Verification

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy" : "irods_policy_enqueue_rule",
                        "delay_conditions" : "<ET>PLUSET 1</ET>",
                        "payload" : {
                            "policy" : "irods_policy_execute_rule",
                            "payload" : {
                                "policy" : "irods_policy_data_verification",
                                "configuration" : {
                                    "attribute" : "irods::verification::type"
                                }
                            }
                        }
                    }                  
                ]
            }
        }

The type of verification to perform is stored as metadata on the resource:

  • catalog
  • filesystem
  • checksum

Policy Composed Capabilities

Storage Tiering Overview

Policy Composed Capability

Storage Tiering

  • Asynchronous Discovery
  • Asynchronous Replication
  • Synchronous Retention
  • Resource associated metadata
  • Identified by 'tiering groups'
{
        "policy" : "irods_policy_enqueue_rule",
        "delay_conditions" : "<EF>REPEAT FOR EVER</EF>",
        "payload" : {
            "policy" : "irods_policy_execute_rule",
            "payload" : {
                "policy_to_invoke" : "irods_policy_storage_tiering",
                "parameters" : {
                    "tier_groups" : ["example_group" ]
                 },
                 "configuration" : {
                 }
             }
        }
}
INPUT null
OUTPUT ruleExecOut

Policy Composed Capability

Asynchronous Configuration for Storage Tiering

Policy Composed Capability

Synchronous Configuration for Storage Tiering

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "read", "write", "rename", "registration", "replication"],
                        "policy"    : "irods_policy_access_time",
                        "configuration" : {
                        }
                    },

                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["read", "write", "get"],
                        "policy"    : "irods_policy_data_restage",
                        "configuration" : {
                        }
                    },

                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["replication"],
                        "policy"    : "irods_policy_tier_group_metadata",
                        "configuration" : {
                        }

                    }
                ]
            }
        }

Policy Composed Capability

Possible Metadata Driven Restage for Storage Tiering

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-metadata_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-metadata_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["set", "add"],
                        "attribute" : "irods::storage_tiering::restage",
                        "value"     : "*.*",
                        "policy"    : "irods_policy_data_restage",
                        "configuration" : {
                        }
                    }
                ]
            }
        }

Data Transfer Nodes Pattern

Policy Composed Capability

Ingress and Egress

  • Asynchronous Discovery
  • Asynchronous Retention
  • Synchronous Replication
  • Resource associated metadata
  • Identified by 'replication groups'
        {
            "policy" : "irods_policy_enqueue_rule",
            "delay_conditions" : "<EF>REPEAT FOR EVER</EF>",
            "payload" : {
                "policy" : "irods_policy_execute_rule",
                "payload" : {
                    "policy_to_invoke" : "irods_policy_query_processor",
                    "parameters" : {
                        "query_string" : "SELECT USER_NAME, COLL_NAME, DATA_NAME, RESC_NAME WHERE COLL_NAME like '/tempZone/home/rods%' AND RESC_NAME IN ('edge_resource_1', 'edge_resource_2')",
                        "query_limit" : 10,
                        "query_type" : "general",
                        "number_of_threads" : 4,
                        "policy_to_invoke" : "irods_policy_data_retention",
                        "configuration" : {
                            "mode" : "trim_single_replica",
                            "source_resource_list" : ["edge_resource_1", "edge_resource_2"]
                        }
                    }
                }
            }
        }

Policy Composed Capability

Asynchronous Retention on Edge Resources

Synchronous Replication from edge to Long Term Storage

        {
            "instance_name": "irods_rule_engine_plugin-event_handler-data_object_modified-instance",
            "plugin_name": "irods_rule_engine_plugin-event_handler-data_object_modified",
            "plugin_specific_configuration": {
                "policies_to_invoke" : [
                    {   "pre_or_post_invocation" : ["post"],
                        "events" : ["create", "write", "registration"],
                        "policy"    : "irods_policy_data_replication",
                        "configuration" : {
                            "source_to_destination_map" : {
                                "edge_resource_0" : ["long_term_resource_0"],
                                "edge_resource_1" : ["long_term_resource_1"],
                            }
                        }
                    }               
                ]
            }
        }

Policy Composed Capability

  • Capabilities become recipes which are easily configured

 

  • A Policy GUI can now become a possibility with the simple manipulation of server JSON

  • Continue to build a library of supported policy engines, driven by the community

  • Data Integrity Capability will now be a collection of engines

Summary - Configuration not Code

Questions?

TRiRODS - Policy Composition

By jason coposky

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