Deprecation in Elasticsearch

What it is:

Deprecation refers to processes and functions that are in the process of being eliminated and (possibly) replaced by newer ones.

Typically, a function will not disappear from one version to the next without warning. Normally this will happen across a number of versions. When you use a deprecated function in intermediate versions, it will continue to work as before, but you will receive warnings that the function in question is intended to disappear in the future.

How it works:

There are a number of ways you can find out which functions have been deprecated, including: deprecation logs, reading the breaking pages documentation and paying attention to warnings.

In a deprecation log:

{"type": "deprecation", "timestamp": "2020-01-16T12:50:11,263+0000", "level": "WARN", "component": "o.e.d.r.a.d.RestDeleteAction", "cluster.name": "docker-cluster", "node.name": "es01", "cluster.uuid": "VGTYFgunQ_STTKVz6YHAGg", "node.id": "wh5J7TJ-RD-pJE4JOUjVpw",  "message": "[types removal] Specifying types in document index requests is deprecated, use the typeless endpoints instead (/{index}/_doc/{id}, /{index}/_doc, or /{index}/_create/{id})."  }

Reading the breaking changes documentation for each version:

https://www.elastic.co/guide/en/elasticsearch/reference/7.5/breaking-changes-7.0.html

In kibana you may also see a warning if you run a deprecated command in the development panel:

#! Deprecation: [types removal] Specifying types in document index requests is deprecated, use the typeless endpoints instead (/{index}/_doc/{id}, /{index}/_doc, or /{index}/_create/{id}).

It is important to act upon these warnings. Although your application still works, ignoring the warnings will almost certainly cause things to malfunction in a future upgrade.

Deprecation API:

There is a depreciation API, which can help point you to deprecated functions on your cluster:

However, you should never depend on the deprecation API alone. Just because the API returns with no issues, it does not mean that everything in your setup will work out of the box when migrating!  This is to be used in addition to looking through the deprecation log and breaking changes documentation.

Examples:

• The removal of document types (“_type”) . Various document types were allowed in a single index in version 6, but this functionality has been removed. You will get warnings if you use document types in queries, and only 1 document type is allowed per index in version 7.  The functionality is expected to be completely removed in version 8.
• The discovery.zen.minimum_master_nodes setting is permitted, but ignored, on 7.x nodes.

There are many more examples to be found in the breaking changes documentation.

Notes and good things to know:

It is important to visit ALL the breaking changes for each minor version between the version you are using and the version you want to upgrade to.

https://www.elastic.co/guide/en/elasticsearch/reference/7.3/breaking-changes-7.3.html

Contains information that is not mentioned on the next page.

https://www.elastic.co/guide/en/elasticsearch/reference/7.5/breaking-changes-7.4.html

The best way is to go to the “breaking changes” page of the version you want to upgrade to, and then use the links to page look through all of the minor version pages down to the one you want to upgrade from, paying particular attention to the major version change (eg. 7.0 )

Opster supports all Elasticsearch versions so If you need help reach out

Overview

A plugin is used to enhance the core functionalities of Elasticsearch. Elasticsearch provides some core plugins as a part of their release installation. In addition to those core plugins, it is possible to write your own custom plugins as well. There are several community plugins available on GitHub for various use cases.

Examples

Get all the instructions for the plugin

sudo bin/elasticsearch-plugin -h

Installing the S3 plugin for storing Elasticsearch snapshots on S3

sudo bin/elasticsearch-plugin install repository-s3

Removing a plugin

sudo bin/elasticsearch-plugin remove repository-s3

Installing a plugin using the file’s path

sudo bin/elasticsearch-plugin install file:///path/to/plugin.zip

Notes and good things to know

• Plugins are installed and removed using the elasticsearch-plugin script, which ships as a part of the Elasticsearch installation and can be found inside the bin/ directory of the Elasticsearch installation path.
• A plugin has to be installed on every node of the cluster and each of the nodes has to be restarted to make the plugin visible.
• You can also download the plugin manually and then install it using the elasticsearch-plugin install command, providing the file name/path of the plugin’s source file.
• When a plugin is removed, you will need to restart every elasticsearch node in order to complete the removal process.

Common issues

• Managing permission issues during and after plugin installation is the most common problem. If Elasticsearch was installed using the deb or rpm package then the plugin has to be installed using the root user, or else you can install the plugin as the user that owns all of the Elasticsearch files.
• In case of deb or rpm package installation, it is important to check the permission of the plugins directory after plugin installation and update the permission if it has been modified using the following command:

chown -R elasticsearch:elasticsearch path_to_plugin_directory 

• If your Elasticsearch nodes are running in a private subnet without internet access, you cannot install a plugin directly. In this case, you can simply download the plugins at once and copy the files inside the plugins directory of the Elasticsearch installation path on every node. The node has to be restarted in this case as well.