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Plugins: Remove pluggability of ZenPing ZenPing is the part of zen discovery which knows how to ping nodes. There is only one alternative implementation, which is just for testing. This change removes the ability to add custom zen pings, and instead hooks in the MockZenPing for tests through an overridden method in MockNode. This also folds in the ZenPingService (which was really just a single method) into ZenDiscovery, and removes the idea of having multiple ZenPing instances. Finally, this was the last usage of the ExtensionPoint classes, so that is also removed here.
94 lines
3.8 KiB
Plaintext
94 lines
3.8 KiB
Plaintext
[[discovery-file]]
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=== File-Based Discovery Plugin
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The file-based discovery plugin uses a list of hosts/ports in a `unicast_hosts.txt` file
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in the `config/discovery-file` directory for unicast discovery.
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[[discovery-file-install]]
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[float]
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==== Installation
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This plugin can be installed using the plugin manager:
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[source,sh]
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----------------------------------------------------------------
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sudo bin/elasticsearch-plugin install discovery-file
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----------------------------------------------------------------
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The plugin must be installed on every node in the cluster, and each node must
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be restarted after installation. Note that installing the plugin will add a
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`discovery-file` directory to the `config` folder, and a default `unicast_hosts.txt`
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file that must be edited with the correct unicast hosts list before starting the node.
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[[discovery-file-remove]]
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[float]
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==== Removal
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The plugin can be removed with the following command:
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[source,sh]
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----------------------------------------------------------------
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sudo bin/elasticsearch-plugin remove discovery-file
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----------------------------------------------------------------
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The node must be stopped before removing the plugin.
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[[discovery-file-usage]]
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[float]
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==== Using the file-based discovery plugin
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The file-based discovery plugin provides the ability to specify the
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unicast hosts list through a simple `unicast_hosts.txt` file that can
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be dynamically updated at any time. The discovery type for this plugin
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is still the default `zen` plugin, so no changes are required to the
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`elasticsearch.yml` config file. This plugin simply provides a facility
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to supply the unicast hosts list for zen discovery through an external
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file that can be updated at any time by a side process.
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For example, this gives a convenient mechanism for an Elasticsearch instance
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that is run in docker containers to be dynamically supplied a list of IP
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addresses to connect to for zen discovery when those IP addresses may not be
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known at node startup.
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Note that the file-based discovery plugin is meant to augment the unicast
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hosts list in `elasticsearch.yml` (if specified), not replace it. Therefore,
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if there are valid unicast host entries in `discovery.zen.ping.unicast.hosts`,
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they will be used in addition to those supplied in `unicast_hosts.txt`.
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Anytime a change is made to the `unicast_hosts.txt` file, even as Elasticsearch
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continues to run, the new changes will be picked up by the plugin and the
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new hosts list will be used for the next pinging round for master election.
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Upon installation of the plugin, a default `unicast_hosts.txt` file will
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be found in the `$CONFIG_DIR/discovery-file` directory. This default file
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will contain some comments about what the file should contain. All comments
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for this file must appear on their lines starting with `#` (i.e. comments
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cannot start in the middle of a line).
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[[discovery-file-format]]
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[float]
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==== unicast_hosts.txt file format
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The format of the file is to specify one unicast host entry per line.
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Each unicast host entry consists of the host (host name or IP address) and
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an optional transport port number. If the port number is specified, is must
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come immediately after the host (on the same line) separated by a `:`.
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If the port number is not specified, a default value of 9300 is used.
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For example, this is an example of `unicast_hosts.txt` for a cluster with
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four nodes that participate in unicast discovery, some of which are not
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running on the default port:
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[source,txt]
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----------------------------------------------------------------
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10.10.10.5
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10.10.10.6:9305
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10.10.10.5:10005
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# an IPv6 address
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[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:9301
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----------------------------------------------------------------
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Host names are allowed instead of IP addresses (similar to
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`discovery.zen.ping.unicast.hosts`), and IPv6 addresses must be
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specified in brackets with the port coming after the brackets.
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