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Install Milvus Cluster with Ansible

This topic introduces how to deploy a Milvus cluster with Ansible. We provide the Docker Host for creating an Ansible playbook and the Container for running the Milvus cluster. The script in this topic is only for running on Ubuntu 20.04 LTS systems. Modify the script commands and parameters if you want to run the Milvus cluster on other versions of operating systems.

Ansible can only be used in test environments. It is not recommended that you deploy Milvus distributed clusters in this way in production environments.

Prerequisites

  • Ensure that your CPU and RAM meet the requirements in Environment Checklist.
  • Hardware: Four servers including three Docker hosts, each with at least four cores of CPU and 8GB of RAM, and one Ansible controller
  • Operating system: Ubuntu 20.04 LTS
  • Software: Ansible Controller

Set up Ansible admin controller

We recommend creating a new Ansible controller on the Ubuntu operating system. Make sure system resources are sufficient for running Ansible tasks. See Installing Ansible for more information.

Download Ansible Milvus node deployment Playbook

Clone Milvus repository from GitHub to download the Ansible Milvus node deployment Playbook.

$ git clone https://github.com/milvus-io/milvus.git

Configure installation files

The inventory.ini and ansible.cfg files are used to control the environment variables and log-in verification methods in Ansible playbook. In the inventory.ini file, the dockernodes section defines all the servers of docker engines. The ansible.cfg section defines all the servers of Milvus coordinators. The node section defines all the servers of Milvus nodes.

Enter the local path to the Playbook and configure the installation files.

$ cd ./milvus/deployments/docker/cluster-distributed-deployment

inventory.ini

Configure inventory.ini to divide hosts in groups in accordance with their roles in the Milvus system.

Add host names, and define docker group and vars.

[dockernodes] #Add docker host names.
dockernode01
dockernode02
dockernode03

[admin] #Add Ansible controller name.
ansible-controller

[coords] #Add the host names of Milvus coordinators.
; Take note the IP of this host VM, and replace 10.170.0.17 with it.
dockernode01

[nodes] #Add the host names of Milvus nodes.
dockernode02

[dependencies] #Add the host names of Milvus dependencies.
; dependencies node will host etcd, minio, pulsar, these 3 roles are the foundation of Milvus. 
; Take note the IP of this host VM, and replace 10.170.0.19 with it.
dockernode03

[docker:children]
dockernodes
coords
nodes
dependencies

[docker:vars]
ansible_python_interpreter= /usr/bin/python3
StrictHostKeyChecking= no

; Setup variables to controll what type of network to use when creating containers.
dependencies_network= host
nodes_network= host

; Setup varibale to controll what version of Milvus image to use.
image= milvusdb/milvus-dev:master-20220412-4781db8a

; Setup static IP addresses of the docker hosts as variable for container environment variable config.
; Before running the playbook, below 4 IP addresses need to be replaced with the IP of your host VM
; on which the etcd, minio, pulsar, coordinators will be hosted.
etcd_ip= 10.170.0.19
minio_ip= 10.170.0.19
pulsar_ip= 10.170.0.19
coords_ip= 10.170.0.17

; Setup container environment which later will be used in container creation.
ETCD_ENDPOINTS= {{etcd_ip}}:2379 
MINIO_ADDRESS= {{minio_ip}}:9000
PULSAR_ADDRESS= pulsar://{{pulsar_ip}}:6650
QUERY_COORD_ADDRESS= {{coords_ip}}:19531
DATA_COORD_ADDRESS= {{coords_ip}}:13333
ROOT_COORD_ADDRESS= {{coords_ip}}:53100
INDEX_COORD_ADDRESS= {{coords_ip}}:31000

ansible.cfg

ansible.cfg controls the action of the playbook, for example, SSH key, etc. Do not set up passphrase via the SSH key on docker hosts. Otherwise, the Ansible SSH connection will fail. We recommend setting up the same username and SSH key on the three hosts and setting up the new user account to execute sudo without a password. Otherwise, you will receive errors that the user name does not match the password or you are not granted elevated privileges when running Ansible playbook.

[defaults]
host_key_checking = False
inventory = inventory.ini # Specify the Inventory file
private_key_file=~/.my_ssh_keys/gpc_sshkey # Specify the SSH key that Ansible uses to access Docker host

deploy-docker.yml

deploy-docker.yml defines the tasks during the installation of Docker. See the code comments in the file for details.

---
- name: setup pre-requisites # Install prerequisite
  hosts: all
  become: yes
  become_user: root
  roles:
    - install-modules
    - configure-hosts-file

- name: install docker
  become: yes
  become_user: root
  hosts: dockernodes
  roles:
    - docker-installation

Test Ansible connectivity

Test the connectivity to Ansible.

$ ansible all -m ping

Add -i in the command to specify the path to the inventory file if you did not specify it in ansible.cfg, otherwise Ansible uses /etc/ansible/hosts.

The terminal returns as follow:

dockernode01 | SUCCESS => {
"changed": false,
"ping": "pong"
}
ansible-controller | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}
dockernode03 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}
dockernode02 | SUCCESS => {
    "changed": false,
    "ping": "pong"
}

Check the Playbook Syntax

Check the syntax of the Playbook.

$ ansible-playbook deploy-docker.yml --syntax-check

Normally, the terminal returns as follow:

playbook: deploy-docker.yml

Install Docker

Install Docker with the Playbook.

$ ansible-playbook deploy-docker.yml

If Docker is successfully installed on the three hosts, the terminal returns as follow:

TASK [docker-installation : Install Docker-CE] *******************************************************************
ok: [dockernode01]
ok: [dockernode03]
ok: [dockernode02]

TASK [docker-installation : Install python3-docker] **************************************************************
ok: [dockernode01]
ok: [dockernode02]
ok: [dockernode03]

TASK [docker-installation : Install docker-compose python3 library] **********************************************
changed: [dockernode01]
changed: [dockernode03]
changed: [dockernode02]

PLAY RECAP *******************************************************************************************************
ansible-controller         : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
dockernode01               : ok=10   changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
dockernode02               : ok=10   changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
dockernode03               : ok=10   changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Verify the installation

Log in to the three hosts with the SSH key, and verify the installation on the hosts.

  • For root host:
$ docker -v
  • For non-root hosts:
$ sudo docker -v

Normally, the terminal returns as follow:

Docker version 20.10.14, build a224086

Check the running status of the containers.

$ docker ps

Check the Syntax

Check the Syntax of deploy-milvus.yml.

$ ansible-playbook deploy-milvus.yml --syntax-check

Normally, the terminal returns as follow:

playbook: deploy-milvus.yml

Create Milvus container

The tasks to create Milvus container are defined in deploy-milvus.yml.

$ ansible-playbook deploy-milvus.yml

The terminal returns:

PLAY [Create milvus-etcd, minio, pulsar] *****************************************************************

TASK [Gathering Facts] ********************************************************************************************
ok: [dockernode03]

TASK [etcd] *******************************************************************************************************
changed: [dockernode03]

TASK [pulsar] *****************************************************************************************************
changed: [dockernode03]

TASK [minio] ******************************************************************************************************
changed: [dockernode03]

PLAY [Create milvus nodes] ****************************************************************************************

TASK [Gathering Facts] ********************************************************************************************
ok: [dockernode02]

TASK [querynode] **************************************************************************************************
changed: [dockernode02]

TASK [datanode] ***************************************************************************************************
changed: [dockernode02]

TASK [indexnode] **************************************************************************************************
changed: [dockernode02]

PLAY [Create milvus coords] ***************************************************************************************

TASK [Gathering Facts] ********************************************************************************************
ok: [dockernode01]

TASK [rootcoord] **************************************************************************************************
changed: [dockernode01]

TASK [datacoord] **************************************************************************************************
changed: [dockernode01]

TASK [querycoord] *************************************************************************************************
changed: [dockernode01]

TASK [indexcoord] *************************************************************************************************
changed: [dockernode01]

TASK [proxy] ******************************************************************************************************
changed: [dockernode01]

PLAY RECAP ********************************************************************************************************
dockernode01               : ok=6    changed=5    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
dockernode02               : ok=4    changed=3    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
dockernode03               : ok=4    changed=3    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Now you have Milvus deployed on the three hosts.

Scale out Milvus nodes

If you need to scale out Milvus nodes, you can follow the steps below to add new docker hosts directly in Ansible playbook.

  1. Prepare host resources as requested in the prerequisites.
  2. Ensure connectivity to the network and host names can be resolved.
  3. Add the new host to the corresponding section in the inventory.ini file. More specifically, add the host name of the new node in the node section as shown in the example below.
[nodes] #Add host names of Milvus nodes.
dockernode02
dockernode04 #This is the host name of the new node.
The new configuration is automatically applied when running the playbook and does not affect the original host configurations. Ansible playbook records all deployments, and when a new host is introduced, a new deployment is made on the new host in order not to affect the original deployment.
  1. After deployment, run the following command to check the running status of the new host.
Docker ps -a

What's next

Having installed Milvus, you can:

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