Deploying a sharded cluster with Docker and MergeCPF
In this article, we will run an InterSystems IRIS cluster using docker and Merge CPF files - a new feature allowing you to configure servers with ease.
On UNIX® and Linux, you can modify the default iris.cpf using a declarative CPF merge file. A merge file is a partial CPF that sets the desired values for any number of parameters upon instance startup. The CPF merge operation works only once for each instance.
Our cluster architecture is very simple, it would consist of one Node1 (master node) and two Data Nodes (check all available roles). Unfortunately, docker-compose cannot deploy to several servers (although it can deploy to remote hosts), so this is useful for local development of sharding-aware data models, tests, and such. For a productive InterSystems IRIS Cluster deployment, you should use either ICM or IKO.
Let's start with docker-compose configuration:
version: '3.7' services: iris1: image: containers.intersystems.com/intersystems/iris:2020.3.0.221.0 init: true command: --key /ISC/iris.key hostname: iris1 environment: - ISC_DATA_DIRECTORY=/ISC/iris.sys.d/sys1 - ISC_CPF_MERGE_FILE=/ISC/CPF2merge-master-instance.conf volumes: - ./:/ISC:delegated ports: - 9011:1972 - 9012:52773 iris2: image: containers.intersystems.com/intersystems/iris:2020.3.0.221.0 command: --key /ISC/iris.key --before 'sleep 60' init: true hostname: iris2 environment: - ISC_DATA_DIRECTORY=/ISC/iris.sys.d/sys2 - ISC_CPF_MERGE_FILE=/ISC/CPF2merge-data-instance.conf volumes: - ./:/ISC:delegated depends_on: - iris1 ports: - 9021:1972 - 9022:52773 iris3: image: containers.intersystems.com/intersystems/iris:2020.3.0.221.0 command: --key /ISC/iris.key --before 'sleep 60' init: true hostname: iris3 environment: - ISC_DATA_DIRECTORY=/ISC/iris.sys.d/sys3 - ISC_CPF_MERGE_FILE=/ISC/CPF2merge-data-instance.conf volumes: - ./:/ISC:delegated depends_on: - iris1 ports: - 9031:1972 - 9032:52773
As you can see we're running a default intersystems/iris:2020.3.0.221.0 image, providing the license key (it must support sharding), persisting the data using Durable %SYS feature, and provide ISC_CPF_MERGE_FILE pointing at our merge files (which are different for Node1 and Data Nodes). Additionally Data Nodes are started a minute late allowing Node1 to start and that's an extremely conservative estimate, on a decent hardware startup time takes seconds tops.
Cluster configuration happens at CPF merge files, let's check them out
[Startup] PasswordHash=FBFE8593AEFA510C27FD184738D6E865A441DE98,u4ocm4qh ShardRole=node1 [config] MaxServerConn=64 MaxServers=64 globals=0,0,400,0,0,0 errlog=1000 routines=32 gmheap=256000 locksiz=1179648
What happens here?
In the [Startup] part we enable Sharding by assigning Node1 role to our cluster. And in
[config]we expand our server a bit allowing more caches and connections. That's all!
[Startup] ShardClusterURL=IRIS://iris1:1972/IRISCLUSTER ShardRole=DATA
For data nodes, we need to provide the URL of the Node1 and the node role.
Check the repository or run this code:
git clone https://github.com/intersystems-ru/iris-container-recipes.git cd iris-container-recipes cd cluster // copy iris.key in cluster folder docker-compose up -d
After starting the InterSystems IRIS cluster you can access it from the browser. User/pass is: _SYSTEM/SYS.
Merge CPF files is a great and simple tool allowing you to configure InterSystems IRIS instances.
Thank you to @Luca Ravazzolo for providing the code and answering all of my questions.