Distributed Service Resource Allocation with Containerized Contrail

Starting with Contrail Release 4.0, the existing centralized Contrail discovery service is replaced with a distributed method of allocating service resources.

Replacement of Centralized Discovery Service

In Contrail releases prior to Release 4.0, the Contrail discovery service is a centralized service resource allocation module with high availability, used primarily to automatically load-balance service resources in the system.

In the previous centralized discovery method, new service resources are registered (published) directly to the Contrail discovery module and allocated to the requester (subscriber) of the service resource, without disrupting the running state of the subscribers.

The centralized discovery method requires using a database to:

synchronize across Contrail discovery nodes.
maintain the list of publishers, subscribers, and the health of published services across reloads.
provide a centralized view of the service allocation and health of the services.

This centralized discovery method resulted in unnecessary system churn when services were falsely marked as down, due to periodic health updates of services made to the database nodes, resulting in reallocation of healthy services.

Starting with Contrail 4.0, the Contrail discovery services centralized resource allocation manager has been removed. Its replacement is a distributed resource allocation list of service nodes, maintained in each module of the system.

New Distributed Resource Allocation Manager

Starting with Contrail Release 4.0, service resources are managed with a distributed allocation manager, with the following features:

Each system module is provisioned with a list of service nodes (publishers).
Each system module randomizes the list of service nodes and uses the resources. The randomized list is expected to be fairly load-balanced.
When currently-used services are down, the system module detects the down immediately and reacts with no downtime by selecting another service from the list. This is distinctly different from the previous model, in which the module would need to contact the discovery service to check for available services, resulting in a finite time loss for allocation, distribution, and application of a new set of services.
When service nodes are added or deleted, the system administrator updates the configuration file of all daemons using the service type of the service node added or deleted, sending a SIGHUP to the respective daemons.
Each daemon randomizes the service list independently and reallocates the resources.

Deprecation of IF-MAP

In Contrail 4.0, the Interface for Metadata Access Points (IF-MAP) methodology has been deprecated. Contrail 4.0 uses CONFIGDB sections in configuration files instead of IF-MAP sections.

Changes in Configuration Files

Table 1 lists configuration files in the Contrail system that have changes to enable the distributed service resource allocation system, starting with Contrail 4.0. In general, the changes include removing (deprecating) discovery server sections and subsections, and adding parameters needed to identify service resources in all modules.

Each daemon randomizes the published service list and uses the resources. Additionally, each daemon provides a SIGHUP handler to manage the addition or deletion of publishers.

Table 1: Contrail 4.0 Changes in Configuration Files
Configuration File	Configuration Parameter	Changes
`contrail-vrouter-agent.conf`	`[DISCOVERY]`	Section deprecated
	`[CONTROL-NODE].servers`	Provisioned list of control-node [role=control] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:5269 10.1.1.12:5269
	`[DNS].servers`	Provisioned list of DNS [role=control] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:53 10.1.1.2:5
	`[DEFAULT].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-control.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULT].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[CONFIGDB].rabbitmq_server_list`	Provisioned list of config-node [role=cfgm] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:5672 10.1.1.2:5672
	`[CONFIGDB].rabbitmq_user`	guest (default string)
	`[CONFIGDB].rabbitmq_password`	guest (default string)
	`[CONFIGDB].config_db_server_list`	Provisioned list of Config DB [role=database] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:9042 10.1.1.2:9042 NOTE: Docker uses 9041 as port
	`[CONFIGDB].certs_store`	Deprecated
	`[CONFIGDB].password`	Deprecated
	`[CONFIGDB].server_url`	Deprecated
	`[CONFIGDB].user`	Deprecated
	`[CONFIGDB].stale_entries_cleanup_timeout`	Deprecated
	`[CONFIGDB].end_of_rib_timeout`	Deprecated
`contrail-dns.conf`
	`[DISCOVERY]`	Deprecated
	`[DEFAULT].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[CONFIGDB].rabbitmq_server_list`	Provisioned list of config-node [role=cfgm] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:5672 10.1.1.2:5672
	`[CONFIGDB].rabbitmq_user`	guest (default string)
	`[CONFIGDB].rabbitmq_password`	guest (default string)
	`[CONFIGDB].config_db_server_list`	Provisioned list of Config DB [role=database] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:9042 10.1.1.2:9042 NOTE: Dockers use 9041 as port
	`[CONFIGDB].certs_store`	Deprecated
	`[CONFIGDB].password`	Deprecated
	`[CONFIGDB].server_url`	Deprecated
	`[CONFIGDB].user`	Deprecated
	`[CONFIGDB].stale_entries_cleanup_timeout`	Deprecated
	`[CONFIGDB].end_of_rib_timeout`	Deprecated
`contrail-collector.conf`	`[DISCOVERY]`	Deprecated
	`[API_SERVER].api_server_list`	Provisioned list of api-servers [role=config] in the format: ip-address:port Example: 10.1.1.1:8082 10.1.1.2:8082
`contrail-alarm-gen.conf`	`[DISCOVERY]`	Deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[API_SERVER].api_server_list`	Provisioned list of api-servers [role=config] in the format: ip-address:port Example: 10.1.1.1:8082 10.1.1.2:8082
	`[REDIS].redis_uve_list`	Provisioned list of redis instances [role=collector] Example: 192.168.0.29:6379 192.168.0.30:6379
`contrail-analytics-api.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[REDIS].redis_uve_list`	Provisioned list of redis instances [role=collector] Example: 192.168.0.29:6379 192.168.0.30:6379
`contrail-api.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-schema.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-svc-monitor.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-device-manager.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in ip-address:port ip-address2:port format Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-analytics-nodemgr.conf`	`[DISCOVERY]`	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-config-nodemgr.conf`	`[DISCOVERY]`	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-control-nodemgr.conf`	`[DISCOVERY]`	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-database-nodemgr.conf`	`[DISCOVERY]`	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-vrouter-nodemgr.conf`	`[DISCOVERY`]	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-query-engine.conf`	`[DISCOVERY]`	Section deprecated
	`[COLLECTOR].server_list`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
`contrail-snmp-collector.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[API_SERVER].api_server_list`	Provisioned list of api-servers [role=config] in the format: ip-address:port Example: 10.1.1.1:8082 10.1.1.2:8082
`contrail-topology.conf`	`[DISCOVERY]`	Section deprecated
	`[DEFAULTS].collectors`	Provisioned list of Collector [role=collector] service providers in the format: ip-address:port ip-address2:port Example: 10.1.1.1:8086 10.1.1.2:8086
	`[API_SERVER].api_server_list`	Provisioned list of api-servers [role=config] in ip-address:port Example: 10.1.1.1:8082 10.1.1.2:8082
Contrail Web UI
`config.global.js`	`config.discovery.server`	Discovery subsection deprecated
	`config.discovery.port`	Discovery subsection deprecated
	`config.cnfg.server_ip`	Provisioned list of Config [role=cfgm] service providers as list of ip-address Example: ['10.1.1.1 10.1.1.2']
	`config.cnfg.server_port`	Server port as a string Example: '8082'
	`config.analytics.server_ip`	Provisioned list of Collector [role=collector] service providers as a list of ip-address Example: ['10.1.1.1 10.1.1.2']
	`config.analytics.server_port`	Server port as a string Example: '8081'
	`config.dns.server_ip`	Provisioned list of Controller [role=control] service providers as a list of ip-address Example: ['10.1.1.1 10.1.1.2']
	`config.dns.server_port`	Server port as a string Example: '8092'

ON THIS PAGE

Distributed Service Resource Allocation with Containerized Contrail

Replacement of Centralized Discovery Service

New Distributed Resource Allocation Manager

Deprecation of IF-MAP

Changes in Configuration Files