72 lines
2.9 KiB
Plaintext
72 lines
2.9 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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:plugin_name: discovery-file
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include::install_remove.asciidoc[]
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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. To enable, add the following in `elasticsearch.yml`:
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[source,yaml]
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----
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discovery.zen.hosts_provider: file
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----
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This plugin simply provides a facility to supply the unicast hosts list for
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zen discovery through an external 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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