Module config

config API

object config¶

config:get([param])¶

Get a configuration applied to the current instance. Optionally, you can pass a configuration option name to get its value.

Parameters:	param (string) – a configuration option name
Return:	an instance configuration

Examples:

The example below shows how to get the full instance configuration:

app:instance001> require('config'):get()
---
- fiber:
    io_collect_interval: null
    too_long_threshold: 0.5
    top:
      enabled: false
  # other configuration values
  # ...

This example shows how to get an iproto.listen option value:

app:instance001> require('config'):get('iproto.listen')
---
- - uri: 127.0.0.1:3301
...

config.get() can also be used in application code to get the value of a custom configuration option.

config:info()¶

Get the current instance’s state in regard to configuration.

Return:	a table containing an instance’s state

The returned state includes the following sections:

• status – one of the following statuses:
  • ready – the configuration is applied successfully
  • check_warnings – the configuration is applied with warnings
  • check_errors – the configuration cannot be applied due to configuration errors
• meta – additional configuration information
• alerts – warnings or errors raised on an attempt to apply the configuration

Examples:

Below are a few examples demonstrating how the info() output might look:

• In the example below, an instance’s state is ready and no warnings are shown:

  app:instance001> require('config'):info()
  ---
  - status: ready
    meta: []
    alerts: []
  ...
  

• In the example below, the instance’s state is check_warnings. The alerts section informs that privileges to the books space for sampleuser cannot be granted because the books space has not created yet:

  app:instance001> require('config'):info()
  ---
  - status: check_warnings
    meta: []
    alerts:
    - type: warn
      message: box.schema.user.grant("sampleuser", "read,write", "space", "books") has
        failed because either the object has not been created yet, or the privilege
        write has failed (separate alert reported)
      timestamp: 2024-02-27T15:07:41.815785+0300
  ...
  

  This warning is cleared when the books space is created.

• In the example below, the instance’s state is check_errors. The alerts section informs that the log.level configuration option has an incorrect value:

  app:instance001> require('config'):info()
  ---
  - status: check_errors
    meta: []
    alerts:
    - type: error
      message: '[cluster_config] log.level: Got 8, but only the following values are
        allowed: 0, fatal, 1, syserror, 2, error, 3, crit, 4, warn, 5, info, 6, verbose,
        7, debug'
      timestamp: 2024-02-29T12:55:54.366810+0300
  ...
  

• In this example, an instance’s state includes information about a centralized storage the instance takes a configuration from:

  app:instance001> require('config'):info()
  ---
  - status: ready
    meta:
      storage:
        revision: 8
        mod_revision:
          /myapp/config/all: 8
    alerts: []
  ...
  

config:reload()¶

Reload the current instance’s configuration. Below are a few use cases when this function can be used:

• A configuration option value specific to this instance is changed in a cluster’s configuration.
• A new instance is added to a replica set.
• A centralized configuration with turned-off configuration reloading is updated. Learn more at Reloading configuration.

config.storage API

The config.storage API allows you to interact with a Tarantool-based centralized configuration storage.

config.storage.put(path, value)¶

Put a value by the specified path.

Parameters:	path (string) – a path to put the value by value (string) – a value to put
Return:	a table containing the following fields: revision: a revision after performing the operation
Rtype:	table

Example:

The example below shows how to read a configuration stored in the source.yaml file using the fio module API and put this configuration by the /myapp/config/all path:

local fio = require('fio')
local cluster_config_handle = fio.open('../../source.yaml')
local cluster_config = cluster_config_handle:read()
local response = config.storage.put('/myapp/config/all', cluster_config)
cluster_config_handle:close()

Example on GitHub: tarantool_config_storage.

config.storage.get(path)¶

Get a value stored by the specified path or prefix.

Parameters:	path (string) – a path or prefix to get a value by; prefixes end with /
Return:	a table containing the following fields: data: a table containing the information about the value: path: a path mod_revision: a last revision at which this value was modified value:: a value revision: a revision after performing the operation
Rtype:	table

Examples:

The example below shows how to get a configuration stored by the /myapp/config/all path:

local response = config.storage.get('/myapp/config/all')

This example shows how to get all configurations stored by the /myapp/ prefix:

local response = config.storage.get('/myapp/')

Example on GitHub: tarantool_config_storage.

config.storage.delete(path)¶

Delete a value stored by the specified path or prefix.

Parameters:	path (string) – a path or prefix to delete the value by; prefixes end with /
Return:	a table containing the following fields: data: a table containing the information about the value: path: a path mod_revision: a last revision at which this value was modified value:: a value revision: a revision after performing the operation
Rtype:	table

Examples:

The example below shows how to delete a configuration stored by the /myapp/config/all path:

local response = config.storage.delete('/myapp/config/all')

In this example, all configuration are deleted:

local response = config.storage.delete('/')

Example on GitHub: tarantool_config_storage.

config.storage.info()¶

Get information about an instance’s connection state.

Return:	a table containing the following fields: status: a connection status, which can be one of the following: connected: if any instance from the quorum is available to the current instance disconnected: if the current instance doesn’t have a connection with the quorum
Rtype:	table

config.storage.txn(request)¶

Make an atomic request.

Parameters:	request (table) – a table containing the following optional fields: predicates: a list of predicates to check. Each predicate is a list that contains: {target, operator, value[, path]} target – one of the following string values: revision, mod_revision, value, count operator – a string value: eq, ne, gt, lt, ge, le or its symbolic equivalent, for example, ==, !=, > value – an unsigned or string value to compare path (optional) – a string value: can be a path with the mod_revision and value target or a path/prefix with the count target on_success: a list with operations to execute if all predicates in the list evaluate to true on_failure: a list with operations to execute if any of a predicate evaluates to false
Return:	a table containing the following fields: data: a table containing response data: responses: the list of responses for all operations is_success: a boolean value indicating whether the predicate is evaluated to true revision: a revision after performing the operation
Rtype:	table

Example:

local response = config.storage.txn({
    predicates = { { 'value', '==', 'v0', '/myapp/config/all' } },
    on_success = { { 'put', '/myapp/config/all', 'v1' } },
    on_failure = { { 'get', '/myapp/config/all' } }
})

Example on GitHub: tarantool_config_storage.