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Merge pull request #63813 from ClickHouse/keeper-cluster-doc

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Improve documentation for from_env and from_zk
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Mikhail f. Shiryaev 2024-05-16 08:57:53 +00:00 committed by GitHub
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docs/en/operations/configuration-files.md
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@ -67,6 +67,8 @@ generates merged configuration file:
</clickhouse> </clickhouse>
``` ```
### Using from_env and from_zk
To specify that a value of an element should be replaced by the value of an environment variable, you can use attribute `from_env`. To specify that a value of an element should be replaced by the value of an environment variable, you can use attribute `from_env`.
Example with `$MAX_QUERY_SIZE = 150000`: Example with `$MAX_QUERY_SIZE = 150000`:
@ -93,6 +95,59 @@ which is equal to
</clickhouse> </clickhouse>
``` ```
The same is possible using `from_zk`:
``` xml
<clickhouse>
<postgresql_port from_zk="/zk_configs/postgresql_port"/>
</clickhouse>
```
```
# clickhouse-keeper-client
/ :) touch /zk_configs
/ :) create /zk_configs/postgresql_port "9005"
/ :) get /zk_configs/postgresql_port
9005
```
which is equal to
``` xml
<clickhouse>
<postgresql_port>9005</postgresql_port>
</clickhouse>
```
#### Default values for from_env and from_zk attributes
It's possible to set the default value and substitute it only if the environment variable or zookeeper node is set using `replace="1"`.
With previous example, but `MAX_QUERY_SIZE` is unset:
``` xml
<clickhouse>
<profiles>
<default>
<max_query_size from_env="MAX_QUERY_SIZE" replace="1">150000</max_query_size>
</default>
</profiles>
</clickhouse>
```
will take the default value
``` xml
<clickhouse>
<profiles>
<default>
<max_query_size>150000</max_query_size>
</default>
</profiles>
</clickhouse>
```
## Substituting Configuration {#substitution} ## Substituting Configuration {#substitution}
The config can define substitutions. There are two types of substitutions: The config can define substitutions. There are two types of substitutions: