Vitess on Kubernetes. followed by a demo of VReplication. Jiten Vaidya

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1 Vitess on Kubernetes followed by a demo of VReplication Jiten Vaidya jiten@planetscale.com

PlanetScale Founded in early 2018 to help operationalize Vitess Sugu Sugumaran

2 A word about me... Jiten Vaidya - Managed teams that operationalized Vitess at Youtube CEO at PlanetScale Founded in early 2018 to help operationalize Vitess Sugu Sugumaran (CTO, Vitess community leader) Offerings Open Source Vitess Support Custom Vitess Development Kubernetes Deployment Manager Cross-cloud DBaaS

3 Show of hands... How many of you know what Vitess is? How many of you are facing scaling problems? How many of you want to run mysql in Cloud?

4 What does Vitess solve? Database Scalability MySQL Guardrails Operation in Cloud

5 Vitess Architecture app server vtctld lockserver shard vttablet app server mysqld vtgate master app server vtgate big data App Vitess vttablet vttablet vttablet vttablet mysqld mysqld mysqld mysqld replicas big data replicas

6 Major users using Vitess In production Evaluating Quiz of Kings

7 Vtgate in Kubernetes Stateless proxy Accepts connections as a MySQL compatible server + over GRPC Supports an http endpoint + Web UI for status Computes target shards Sends queries to vttablets for targeted shards Receives, collates and serves response to application Vtgates can be created as load increase Start n vtgates as a Replica Set For co-located workloads start one vtgate per node and expose with a ClusterIP

8 Vtctld in Kubernetes Vitess Control Plane Serves a Web UI Operational commands Status Topology browser Serves an API over GRPC Used by vtctlclient tool Supports resharding workflows Start one or two vtctld processes per cell Start them as a Deployments Expose them behind a Service

9 lockserver (etcd) in Kubernetes Knits the Vitess cluster together Backing store for metadata Service discovery Topology VSchema Not used for query serving Needed for any change in topology Add a keyspace Add a shard to keyspace Add a tablet to a shard Change master for a shard One global cluster One cluster per cell (optional) Use etcd-operator to spin out a cluster Expose etcd cluster behind a Service

10 Tablet (vttablet + mysqld) in Kubernetes Vitess Tablet is a combination of a mysqld instance and a corresponding vttablet process Each tablet requires a unique id in Vitess cluster Tablets can be of type: master, replica, rdonly Tablets of type replica can be promoted to master and should have low replica lag 2 containers in the same pod Communicate over Unix socket Unix socket created in Shared Volume Local Persistent Volume for data One master, 2 replicas with semi-sync replication enabled for high availability Replicas should not be co-located with other members of shard ( Anti-Affinity )

11 Authentication/Secrets management What secrets are needed? Application -> Vtgate authentication Vttablet -> mysqld authentication for various roles that Vitess supports (app, dba, replication, filtered replication etc). TLS certs and keys for GRPC traffic over TLS (optional) TLS certs and keys for binary logs over TLS (optional) TLS certs and keys for client authorization and authentication over TLS (optional) Use Kubernetes Secrets and mount them in pods

12 High Availability Planned reparent Coordinated via lockserver Existing transactions are allowed to complete New transactions are buffered by vtgate New master is made writable Replicas are made slaves of the new master Query serving is resumed Unplanned reparent Orchestrator TabletExternallyReparented Resharding No interruption to query traffic during resharding

13 Supporting multiple cells Vitess cell is the equivalent of a failure domain (e.g. AWS availability zones or regions) Not necessarily the same as Kubernetes failure domain. Choice to use global lockserver cluster OR use one lockserver cluster per cell. Global lockserver cluster typically outside of Kubernetes. Expose lockserver behind a service definition. If using etcd use etcd-operator to start per cell cluster.

14 Vitess clusters spanning Kubernetes clusters Global lockserver cluster should be outside of Kubernetes While creating each cell designate which Kubernetes cluster it resides in Must have a non-overlapping ip space and all addresses must be routable. pod to pod communication Needed for mysql replication and query serving Achieved by Peering and Routing

15 Part II: Vitess in Action Vitess super power: filtered replication aka VReplication Ability to consume binary replication log, and apply sharding or other logic to it Shard splits (aka resharding) Sharded Materialized Views

16 Splitting a Shard in Vitess Step 1 - Vitess in-front of app 1 shard. app server vtgate Vttablet (Shard -) mysqld

17 Live Resharding Filtered Replication Step 2 - Split Shard Vttablet (Shard 00-80) mysqld app server vtgate Vttablet (Shard 0) mysqld Vttablet (Shard 80-FF) mysqld 17

18 Live Resharding Step 3 - Split Shard Vttablet (Shard 00-80) mysqld app server vtgate Vttablet (Shard 80-FF) mysqld

19 Hot off the presses... Sharded Materialized Views (Ability to shard using more than one sharding key using replication streams) M shards using key1 -> N shards using key2 M * N replication streams

20 Materialized view example

21 Demo lookup unsharded user sharded name_user_idx name uid user id name product Id description order id uid pid mname merchant sharded merchant name

22 Questions?

Vitess. The Complete Story. Percona Live Data Performance Conference April 20, Sugu Sougoumarane, Anthony Yeh.

Vitess. The Complete Story. Percona Live Data Performance Conference April 20, Sugu Sougoumarane, Anthony Yeh. Vitess The Complete Story Percona Live Data Performance Conference April 20, 2016 Sugu Sougoumarane, Anthony Yeh http://vitess.io What is Vitess? "Flipkart's developers might soon forget what MySQL sharding