Install Elasticsearch, Kibana & Cerebro

Install Kibana

yum remove kibana (This will remove the kibana and kibana config which exist earlier)

Download Kibana RPM from the below link
https://www.elastic.co/guide/en/kibana/5.4/rpm.html
> touch /var/log/kibana.log
> chown -R kibana:kibana /var/log/kibana.log
> vi /etc/kibana/kibana.yml
server.port: 5601
server.host: "HOST_NAME"
server.name: "SERVER_NAME"
elasticsearch.url: "http://ES_URL:9200"

logging.dest: /var/log/kibana.log

Start Kibana & Status on CentOS 7
> systemctl start kibana
> systemctl status kibana

Check the log
> journalctl -u kibana

Check the Kibana port open
nc -z localhost  5601

Install Cerebro
> wget https://github.com/lmenezes/cerebro/releases/download/v0.8.3/cerebro-0.8.3.tgz
> tar -xvf cerebro-0.8.3.tgz

Edit cerebro service file in centOS 7 and update the location where cerebro is extracted
> vim /etc/systemd/system/cerebro.service

Edit cerebro configuration and update the Elasticsearch config which it needs to have lookup
>  vim cerebro-0.8.3/conf/application.conf
      Update the ES host server, port and ES Cluster name by enabling

>  systemctl start cerebro
> systemctl status cerebro

Or manually start
> ./bin/cerebro -Dhttp.port=1234 -Dhttp.address=127.0.0.1

   
Check the log
> journalctl -u cerebro

Check the Cerebro port open
nc -z localhost  9000

Install Elasticsearch
     Download from the link: 
          https://www.elastic.co/guide/en/elasticsearch/reference/5.4/gs-installation.html
     Increase the file max in your linux 
        > sysctl -w fs.file-max=500000
     Linux Scheduler (Cron) to purge the ES logs based on the cluster name
       > 0 * * * * /bin/bash -c "/bin/find /var/log/elasticsearch -type f | /bin/grep -Pi '(ent\-stage1\-es)(\d{1,4}\-?){1,3}' | /bin/xargs rm -f"
 
    Increase the JVM for ES (Min and Max memory)
     > vim /etc/elasticsearch/jvm.options
         -Xms8GB
         -Xmx8GB

   Modify the ES Configuration
    > vim /etc/elasticsearch/elasticsearch.yml
         cluster.name: ent-stage1-es
          node.master: true
          node.data: false (For Data Nodes keep this flag to true)
          node.ingest: false (For Ingest Nodes keep this flag to true)
          path.data: /mnt/elasticsearch-data
          path.logs: /var/log/elasticsearch
          network.host: 0.0.0.0
          http.port: 9200
          transport.tcp.port: 9300
       
          Configure only the master, datanodes will be linked based on the cluster name we keep across the servers
         discovery.zen.ping.unicast.hosts: ["ES_MASTER_NODE_IP1", "ES_MASTER_NODE_IP2", "ES_MASTER_NODE_IP3"]
         Configure  1 or 3 or 5 Master nodes in Odd numbers to avoid split brain
         discovery.zen.minimum_master_nodes: 1

   Note : a) Cluster name should be same in Master Node, DataNodes and other nodes. Keep master true for master node and others false. Keep the master either 1 or 3 to avoid split brain. Refer ES documentation to know more about it.

Master Node: Keep only node.master: true if you want master node
Data Node:  Keep only node.data: true if you want data node
Ingest Node: Keep only node.ingest: true if you want ingest node
Co-ordinate Node: Keep node.master: false, node.data: false and node.ingest: false and dedicated node will be available for co-ordination as co-ordinate node.
   
>  systemctl start elasticsearch
> systemctl status elasticsearch
   
Check the log
> journalctl -u elasticsearch

Check the ElasticSearch port open
nc -z localhost 9200

Add or Remove x-pack in ES
> cd /usr/share/elasticsearch/bin/
./elasticsearch-plugin <install|remove> x-pack

Exclude / Decommission a node
First run the below query in kibana. Once the shards gets moved to other data nodes than shutdown the elasticsearch on that node. You can use cerebro overview to click the node and see the docs availability in the instance if any.

PUT _cluster/settings
{
  "transient" :{
      "cluster.routing.allocation.exclude._ip" : "<IP_ADDRESS>"
   }

}

Note: If master and data been the same node still you can run the above settings to move the shards from master node to data node.

Adding a node (Data)
Install ES with the same version on the node same as other nodes in the cluster and keep the cluster.name in the elasticsearch.yml file same as other nodes, other fields node.data: true and bring the ES up in new node. So, based on the cluster name new node attach to the existing cluster.

Adding a node (Master):
Install ES with the same version on the node same as other nodes in the cluster and keep the cluster.name in the elasticsearch.yml file same as other nodes, other fields node.master: true and bring the ES up in new node. So, based on the cluster name new node attach to the existing cluster.

You may need to edit the elasticsearch.yml file add the new node (master) ip in the discovery.zen.ping.unicast.hosts and increment the discovery.zen.minimum_master_nodes.

System Configuration Suggestion
1) Try to have r5 instance types for Master nodes and i3 for data nodes. As master node need more memory and i3 for data has more IOPS.

Git Bash

Git Bash
----------
- Git Clone project (Get the project into your local)
  git clone <git_url>
 
- Command will show the git master (origin)
    git branch

- Command will fetch everything from the master
    git fetch

- Checkout the branch / switch to existing branch
    git checkout <branch_name>

- Revert a single file (Complete revert like SVN)
   git checkout <file_name_includes_path>

 - Creating a new branch 'branch_name'
    git checkout -b <branch_name>   

- Merge specific commit id (Advantage it pushes the same commit version over new branch)
   git cherry-pick <218c4e40654a2d53fdaf3f1b47a58867f432b8ed>

- Changes which is in local and not in remote
   git log --branches --not --remotes

- Pull the changes into local from git
  git pull origin <branch_name>

- Hard reset from local cahanges
  git reset --hard HEAD^

- Unstagged a staged file
  git reset HEAD .

- Add .gitignore file
  touch .gitignore

- Push local changes file into staged
  git add <FileName>

- Commit the file into git (From unstagged to stagged)
  git commit -m 'commit message' <filename>

  - Push the changes into remote branch from local
  git push -u origin <branch_name>

- Show the differences in local
   git diff .

- Git stash of switching between branches (store the files temperoarty storage and switch to branch (new)). It will help you to store and switch between branches
  git stash

- Stashing untracked files (save)
$ git stash -u or $ git stash --include-untracked

- save specific file file specific messages. -u untracked files to push untracked files.
git stash push -u -m "<your message>" <filename_includes_path> [<filename_includes_path>]

- Git show the stash files
git stash show stash@{1}

- Git stash show the stash files diff
git stash show -p stash@{1}

- see the `git stash list` once you see choose and apply specific. --index will stage the file in the same location where you kept earlier
git stash apply stash@{1} --index 

- Popping your stash removes the changes from your stash and reapplies the last saved state
git stash pop

- Delete from git stash (storage) the latest
git stash drop [stash_id]

- Remove all from stash
git stash clear

How to Merge:
--------------
git checkout <working_branch>
git pull origin <working_branch>
git checkout <master_branch_source_branch>
git pull origin <master_branch_source_branch>
git merge <working_branch_which_you_want_to_merge_in_source>
    (Resolve the conflicts if any)
    vi <file_name>
git add <resolved_conflict_files>
git commit -m "" <resolved_conflict_files>
git push -u origin <master_branch_source_branch>