Installing Elasticsearch

This is an overview of the Elasticsearch (ES) installation process. For upgrading Elasticsearch, see Upgrading Elasticsearch. For adding nodes to an existing Elasticsearch cluster, see Adding Nodes to an ES Cluster.

Prepare for installation.
1. From the Swarm bundle download, get the latest Elasticsearch RPM and Swarm Search RPM, which installs plugins and support utilities.
```
elasticsearch-VERSION.rpm
caringo-elasticsearch-search-VERSION.noarch.rpm
```
2. Install the Caringo RPM public key that is included with the distribution bundle by running the following command:
```
rpm --import RPM-GPG-KEY
rpm --import GPG-KEY-elasticsearch
```
On each ES server, install and configure the Elasticsearch components.
1. Install the RPMs. Do not attempt to install with rpm – it does not install dependencies like python3.
```
yum install elasticsearch-VERSION.rpm
yum install caringo-elasticsearch-search-VERSION.noarch.rpm
```
2. Complete configuration of Elasticsearch and its environment. See Configuring Elasticsearch.
  After configuring ES nodes, choose either option to perform:
  1. Start the service on each node.
    systemctl start elasticsearch
  2. Reboot each nodes to start automatically.
    Single-node ES cluster
    
    If you are implementing a single-node ES cluster, you need to set the number of replicas to zero to avoid yellow status from having too few nodes. See Scaling Elasticsearch.
3. Verify the mlockall setting is true. Contact DataCore Support if it is not.
```
curl -XGET "ES_HOST:9200/_nodes/process?pretty"
```
4. Verify the HTTP_PROXY and http_proxy environment variables are not set if cURL requests do not send an expected response. Implementing a proxy for root users commands causes communication issues between ES nodes if implemented by an IT organization or security policy.
5. Proceed to the next server.
At this point, all ES servers should be installed and started. Use one of these methods to verify Elasticsearch is running (the status is yellow or green):
```
curl -XGET ES_HOST:9200/_cluster/health
```
```
systemctl status elasticsearch
```
1. Verify the HTTP_PROXY and http_proxy environment variables are not set if cURL requests do not send an expected response. Implementing a proxy for root users commands causes communication issues between ES nodes if implemented by an IT organization or security policy.
Tip

When troubleshooting Elasticsearch issues, run the status command (systemctl status elasticsearch) and then look at the log entries:
/var/log/elasticsearch/CLUSTERNAME.log
In the Swarm UI, create a new search feed. (See Managing Feeds.)
1. Verify the [storage cluster] managementPassword is set properly in the gateway.cfg file if errors are encountered during feed creation. Correct the value and restart the gateway service if a change is needed.
  Best practice
  
  Do not skip creating a search feed if you have an available Elasticsearch cluster with enough resources. A search feed simplifies enumerating your buckets/domains/clusters and making use of your valuable metadata.
  Indexing is performed when the feed shows 0 "pending evaluation".

Tip

To set up the ability to restore search data on demand, see Snapshot and Restore Search Data.