Download - Cisco: Application clustering with Couchbase – Couchbase Connect 2016

Clint Ricker

Couchbase Application Clustering

2© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential

• Solutions Architect, Office of the CTO

• SP Video

Me


• Shipping Couchbase in service provider grade software since 2012

• Running in mission critical, very large scale on-prem and AAS offerings around the world

• Datasets of billions of records

Cisco / Couchbase


• Creating a clustered application glued together by Couchbase

• Use Couchbase / lightweight code snippets instead of common datacenter technologies

• Replacing Zookeeper, Eureka, Consul, Rabbit/HornetMQ, etc…

What


What

App Instance

App Instance

App Instance

Couchbase

App Instance

App Instance

App Instance

Couchbase Shared Storage

Dependent Databases

Zookeeper

Consul

RabbitMQ

Load Balancer Load Balancer


• Complexity kills • Lower machine count• Organizational needs• Application needs• Love of roll your own• Very minimal feature set

Why


• More application code to maintain• Schema changes are difficult• Existing platform stack • Less sensitivity to deployment

footprint• Very minimal feature set

Why not


Global Distributed Lock



• Used to ensure certain activities are globally serialized

• Typically provided by Consul / Zookeeper / etc


Global Distributed Lockuint64_t CBGetLock(char *lockKey, int objectLockTimeout) {

if (status == CBSTATUS_SUCCESS) { for (i = 0; i < retries; i++) { status = CBObjGet(buf, &cas, lockKey,objectLockTimeout); if (status >= 0) { return cas; } } } return CBSTATUS_FAILURE;}


Leader Election


Leader Election

• Used to have a dynamically dedicated master instance for ongoing activity

• Common for frequent maintenance needs

• Typically provided by Consul, Zookeeper, etc…


Leader Election


Leader Electionuint64_t CBElectMasterPrivate(char *masterKey, int ttl, uint64_t masterKeyCas) {

if (masterKeyCas > 0) { status = CBObjReplace(masterKey, "master", masterKeyCas, ttl); } else { status = CBObjSet(masterKey, "master", masterKeyCas, ttl); }

if (status == CBSTATUS_SUCCESS) { for (i = 0; i < retries; i++) { status = CBObjGet(buf, &cas, masterKey, NOLOCK); if (status >= 0) { return cas; } } CBObjDeleteCas(masterKey, cas); return CBSTATUS_FAILURE; } return CBSTATUS_FAILURE;}


Discovery Service


Discovery Service

• Used to discover endpoints for specific services or the total set of nodes in the cluster

• Supports basic load balancing and health check

• Often provided by Consul, Eureka, DNS, etc…


Advertise


<NodeList><Node>

<NodeName>appInstance1</NodeName><Updated>2016-10-24T12:23:42Z</Updated><Address>172.31.31.15:80</Address>

</Node></NodeList><NodeList>

<Node><NodeName>appInstance2</NodeName><Updated>2016-10-24T12:23:41Z</Updated><Address>172.17.126.2:80</Address>

</Node></NodeList>

Example


Discovery


Discovery

Couchbase

App2 Service Instance




Advertise “foo”, “instance ip address”

Lookup “foo”, choose instance Send request to address of selected instance


Shared Queues


Shared Queues

• Create shared queues that are polled by set of nodes

• Typically provided by HornetQ, RabbitMQ, etc…


Shared Queue Add


Shared Queue Read


Transactions


Transactions

• Create a generic globally shared transaction system with rollback

• Typically provided by HornetQ, RabbitMQ, etc…


Transactions

App1 Service InstanceIncoming request



App1 Service InstanceApp1 Service Instance

LB

Service requestw/callback URL

Service requestw/callback URL

Callback

Callback


If transaction failed or timed out

1

2

Create Transaction

Transaction State Record w/state=active and time=currentTime

Transaction Log Record

1

2

4

Close Transaction

Delete Transaction State Record

Delete Transaction Log

1

2

3

RollbackEither synchronously with failure or discovered through query of transaction state records

Pull transaction log

Iterate through transaction log in reverse

Undo each activity

1

2

3

Transactions

Update Transaction state record with state=active and time=currentTime

Append Activity to Transaction Log Record

1

2

Execute Activity

Download - Cisco: Application clustering with Couchbase – Couchbase Connect 2016

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