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README.md

README.md

reponame layout page title tags date
elasticsearch-cluster
repo
ElasticSearch Cluster on Docker 1.12 Swarm
elasticsearch, docker
2016-11-19

Machines

For this example configuration, set up 3 Ubuntu virtual machines running in AWS:

  • manager1
  • worker1
  • worker2

Security Group:

  • Create a security group with port 22 (ssh) inbound
  • Note down the created security group ID
  • Edit the security group and add rules to allow required open ports between Docker nodes
    • Source address for all rules is the created security group ID
    • TCP inbound: 2377, 4789, 7946
    • UDP inbound: 2377, 4789

OS Setup

Install Docker

Install Docker according to install instructions

sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
echo "deb https://apt.dockerproject.org/repo ubuntu-xenial main" | sudo tee /etc/apt/sources.list.d/docker.list
sudo apt-get update
sudo apt-get install -y docker-engine

Set required params

ElasticSearch will fail to start if max_map_count is set too low

# set for current session
sysctl -w vm.max_map_count=262144

# set at boot
sed -i '/vm.max_map_count/d' /etc/sysctl.conf
echo "vm.max_map_count = 262144" >> /etc/sysctl.conf

Docker Swarm

Create a cluster according to the new (v1.12) instructions

On manager1

docker swarm init --advertise-addr <MANAGER-IP>

Replace <MANAGER-IP> with reachable address. For nodes in the same VPC this can (and should) be the private IP listed in AWS. If testing across regions then this may need to be the AWS public IP.

swarm init output will include the swarm join command which must be run on worker1 and worker2

docker swarm join \
    --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
    192.168.99.100:2377

Check swarm status

On manager1 run commands and verify output is sane

docker info
docker node ls

Docker Network

Docker networkng overlay-security-model

Create an overlay network with encryption enabled for secure communication between nodes.

docker network create \
  --driver overlay \
  --subnet 10.0.9.0/24 \
  --opt encrypted \
  enc-net

ElasticSearch service

On a Docker master node.

Create the docker service in global mode. This will run one instance on each available node

docker service create \
  --mode global \
  --name elasticsearch \
  --network enc-net \
  --publish 9200:9200 \
  elasticsearch bash -c 'ip addr && IP=$(ip addr | awk -F"[ /]*" "/inet .*\/24/{print \$3}") && \
      echo publish_host=$IP && \
      exec /docker-entrypoint.sh -Enetwork.bind_host=0.0.0.0 -Enetwork.publish_host=$IP -Ediscovery.zen.minimum_master_nodes=2 -Ediscovery.zen.ping.unicast.hosts=tasks.elasticsearch'

Notes:

  • The argument --publish 9200:9200 exposes port 9200 on each host.
    • This argument can (and should) be removed in non-test environments where elasticsearch will be used with linked services
    • Use with caution. ElasticSearch warns "Never expose an unprotected node to the public internet"
  • The publish_host discovery is scripted above to find the 10.0.9.X address of the node (in the encrypted overlay network). Auto-discovery settings don't work correctly here to figure out the right address
  • tasks.elasticsearch is a special DNS address for the elasticsearch cluster which lists out each of the node addresses
  • Docs for Zen Discovery are available here
  • Docs for ElasticSearch network options are available here

Docker Service Status

Verify service status on master node

docker service ps elasticsearch

Example output:

ID                         NAME               IMAGE          NODE      DESIRED STATE  CURRENT STATE           ERROR
8dhouf08d48t38vh94aqfw7wu  elasticsearch      elasticsearch  manager1  Running        Running 34 seconds ago
2wcm231uzcrcmvd1se3sakhtk   \_ elasticsearch  elasticsearch  worker1   Running        Running 34 seconds ago
cjw8npstwi1zqythx1rhr75fj   \_ elasticsearch  elasticsearch  worker2   Running        Running 34 seconds ago

Check logs for cluster status on each Docker node

docker logs $(docker ps -aq) | grep o.e.c.s.ClusterService
[2016-11-18T18:44:05,813][INFO ][o.e.c.s.ClusterService   ] [epbWb8a] new_master {epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300}, added {k9P08mI}{k9P08mIURR6eJNjSFbJc4w}{SOjMEOu5QhWXgRq0nsRYkA}{10.0.9.5}{10.0.9.5:9300},{knSkfDC}{knSkfDCnRA2i0-caESm2JA}{XgSMoGUnRdeYAsxWn7QzmQ}{10.0.9.4}{10.0.9.4:9300},}, reason: zen-disco-elected-as-master ([2] nodes joined)[{k9P08mI}{k9P08mIURR6eJNjSFbJc4w}{SOjMEOu5QhWXgRq0nsRYkA}{10.0.9.5}{10.0.9.5:9300}, {knSkfDC}{knSkfDCnRA2i0-caESm2JA}{XgSMoGUnRdeYAsxWn7QzmQ}{10.0.9.4}{10.0.9.4:9300}]
[2016-11-18T18:44:05,832][INFO ][o.e.c.s.ClusterService   ] [knSkfDC] detected_master {epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300}, added {k9P08mI}{k9P08mIURR6eJNjSFbJc4w}{SOjMEOu5QhWXgRq0nsRYkA}{10.0.9.5}{10.0.9.5:9300},{epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300},}, reason: zen-disco-receive(from master [master {epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300} committed version [1]])
[2016-11-18T18:44:05,832][INFO ][o.e.c.s.ClusterService   ] [k9P08mI] detected_master {epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300}, added {knSkfDC}{knSkfDCnRA2i0-caESm2JA}{XgSMoGUnRdeYAsxWn7QzmQ}{10.0.9.4}{10.0.9.4:9300},{epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300},}, reason: zen-disco-receive(from master [master {epbWb8a}{epbWb8a-RE2lbXcLn8bN1Q}{thuHs3dBQWKcldQDG4_ijg}{10.0.9.3}{10.0.9.3:9300} committed version [1]])

Note that all 3 nodes have detected epbWb8a as the master

ElasticSearch Cluster

Initial Health

On any node run the following

curl 'localhost:9200/_cluster/health?pretty'

Ensure that the cluster status is green, and that number of nodes is as expected

{
  "cluster_name" : "elasticsearch",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 3,
...

Test an Index

Add an index with shard and replica settings

curl -XPUT 'localhost:9200/blogs?pretty' -d'
{
   "settings" : {
      "number_of_shards" : 10,
      "number_of_replicas" : 1
   }
}'
To modify replica config later
curl -XPUT 'localhost:9200/blogs/_settings?pretty' -d'
{
   "settings" : {
      "number_of_replicas" : 2
   }
}'

Add some data

curl -XPUT 'localhost:9200/blogs/entry/123?pretty' -d'
{
  "title": "My first blog entry",
  "text":  "Just trying this out...",
  "date":  "2016/11/18"
}'
curl -XPUT 'localhost:9200/blogs/entry/456?pretty' -d'
{
  "title": "My second blog entry",
  "text":  "Still trying this out...",
  "date":  "2016/11/19"
}'

Verify replication

Check cluster health again, this time specifically for the blogs index

curl 'localhost:9200/_cluster/health/blogs?pretty'
{
  "cluster_name" : "elasticsearch",
  "status" : "green",
  "timed_out" : false,
  "number_of_nodes" : 3,
  "number_of_data_nodes" : 3,
  "active_primary_shards" : 10,
  "active_shards" : 20,

Kibana service

Create a service for kibana linked to the elasticsearch service

docker service create \
  --mode global \
  --name kibana \
  --network enc-net \
  --publish 5601:5601 \
  kibana

Note that no --link is required (or possible) for services. Instead all services are exposed on their network with their service name. Because we used the name elasticsearch which kibana expects by default, no additional config options are required.

For further config options see the docker hub: kibana page

Connect to Kibana

Use ssh to forward port 5601 to one of your nodes

ssh -NL 5601:localhost:5601 manager1

Open http://localhost:5601 in your web browser

When prompted for the default index enter blogs

Note that the Kibana searches default to only last 15 minutes. This is changed with the date picker in the top right corner.