CERN IT Department CH-1211 Genève 23 Switzerland PES 1 Ermis service for DNS Load Balancer configuration HEPiX Fall 2014 Aris Angelogiannopoulos, CERN IT-PES/PS Ignacio Reguero, CERN IT-PES/PS

CERN IT Department CH-1211 Genève 23 Switzerland PES 2 Outline Core concepts DNS Load Balancing at CERN Motivation and Purpose Ermis Gateway Ermis Gateway Architecture Miscellaneous

CERN IT Department CH-1211 Genève 23 Switzerland PES 3 Core Concepts (Just in case) Load Balancing ● Scale a single service by spreading it to multiple back-end nodes High Availability ● The end user must always “see” the service as functional ● Service should be up even if some front or back-end nodes fail

CERN IT Department CH-1211 Genève 23 Switzerland PES 4 Core Concepts (2/2) Service Manager's concerns: ● Implement High Availability at the application Layer  No single point of failure  Replicate physical nodes among independent subnets  Replicate VM s among different availability zones ● Service components are expected to fail  Hardware failures ( HDD, Switches, NIC's, Electricity etc )  Software failures ( Bugs )  Human Errors

CERN IT Department CH-1211 Genève 23 Switzerland PES 5 DNS Load Balancing at CERN (1/4)

CERN IT Department CH-1211 Genève 23 Switzerland PES 6 DNS Load Balancing at CERN (2/4)  We use a client server architecture:  LBD Master: Server reports to DNS service  LB Client: Runs in the hosts, triggered by SNMP request

CERN IT Department CH-1211 Genève 23 Switzerland PES 7 DNS Load Balancing at CERN (3/4) 1.LB Clients in the host provide LBD Master(through SNMP) with: load metrics availability checks 2. The LBD Master decides which IP should be pointed by an LB Alias 3. The LBD Master sends dynamic DNS requests to update the IP address pointed by the LB Alias ● The LBD Master uses a fail-over slave server for high availability

CERN IT Department CH-1211 Genève 23 Switzerland PES 8 DNS Load Balancing at CERN (4/4) Service is provided for 258 (and rising) different aliases

CERN IT Department CH-1211 Genève 23 Switzerland PES 9 Motivation and Purpose Motivation  Creating new DNS Aliases in the cloud is time-consuming  Ticket to Config team -> Ticket to Network Ops  Lots of verbal and time-consuming communication  Waiting time for both can be high Purpose  Goal is to provide LBaaS to the end users of the cloud  Fast CRUD of LB Aliases in the CERN cloud  No more tickets to the Network Group  Simplifies the procedure of creating LB Aliases

CERN IT Department CH-1211 Genève 23 Switzerland PES 10 Ermis Gateway What is it? RESTful service that manages the configuration of DNS LB ● Django-Tastypie ● SOAP interface to Network Group ● CRUD of LB Aliases ● Aim is to provide LBaaS to the cloud end users ● Developed and tested using Agile techniques

CERN IT Department CH-1211 Genève 23 Switzerland PES 11 Ermis Gateway Architecture (1/2) ● Design ● Model includes information about an Alias ● Alias associated with a hostgroup or tenant ● CRUD on model data ● Authentication ● Kerberos ticket

CERN IT Department CH-1211 Genève 23 Switzerland PES 12 Ermis Gateway Architecture (1/2) ● Authorization  Egroups (CERN interface for managing groups of people)  Openstack  Use of the Openstack identity service (keystone)  Foreman (under development)  Alias creation for machines on the same hostgroup

CERN IT Department CH-1211 Genève 23 Switzerland PES 13 Ermis Gateway Architecture (2/2)

CERN IT Department CH-1211 Genève 23 Switzerland PES 14 LBD configuration ● LBD configuration  Config file is created via the Ermis data

CERN IT Department CH-1211 Genève 23 Switzerland PES 15 Miscellaneous ● Miscellaneous  API endpoint ● REST calls to the service available  CLI available  Web Front available ● (Internal only)

CERN IT Department CH-1211 Genève 23 Switzerland PES 16 Thank you! Questions?