Set runtime configuration via pgagroal-cli
#329
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fluca1978
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Mar 30, 2023
This commit introduces the `config-set` in `pgagroal-cli` to allow the
user to ask the pooler to change a configuration setting.
As a simple usage example:
pgagroal-cli config-set log_level debug
The idea is to write over the communication socket the parameter name
and the parameter value, so that the system can understand what has to
do.
In order to achieve the capability to dynamically set a single
parameter, a new utility function named
'pgagroal_appy_main_configuration' has been created. Such
function is now the backbone of the configuration reading process.
Other internal functions have been added to easily manage the dynamic
changes of pieces of structures, e.g., `struct hba` and alike.
The code that loads the initial configuration out of the configuration
files has been refactored in order to use these new utility functions
so to keep the whole system coherent.
When a request to dynamically change a single parameter arrives, the
system creates a clone of the currently running configuration, than
try to apply on such a clone the new setting, and in the case of
success, swaps the cloned configuration with the currently running
one, so that the currently running one becomes the (changed) cloned.
In the case of failure, e.g., if the configuration change cannot be
applied because it requires a restart, the cloned configuration is
destroyed and the system keeps running with the previous one.
The answer of a `config-set` command is a `config-get` for the same
setting, that is the system sends over the communication socket the
value of the setting requested to be changed. If the final value has
changed, the `pgagroal-cli` will receive the new value, otherwise if
the old value is kept, the old value will be sent. This allows
for automation of `pgagroal-cli config-set` usage, so that it becomes
easy to test back when a parameter have been applied.
The `pgagroal-cli` is responsible to understand if the change did take
effect, so it does compare the sent value with the received answer,
and if they are the same it assumes there was an error. In case of
failure, a return error code is returned, otherwise zero on success.
If the `pgagroal-cli` is used with the verbose flag, the ending result
will print out the status of the command and the value of the setting
as done by `config-get`.
This commit also changed some management debug levels to `debug`
consistently between `config-get` and `config-set` implementations.
Documentation updated.
Shell completions updated.
Close agroal#329
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Related to #328 :
pgagroal-clishould provide a capability to set some run-time configuration parameters while the system is running.I imagine a command line like the following one:
The workflow should be pretty much the following one:
In the case the parameter cannot be changed on the fly, at step 2, then step 3 will report back the current setting, otherwise the new setting.
I see the need for refactoring of the function
pgagroal_read_configurationhttps://github.com/agroal/pgagroal/blob/master/src/libpgagroal/configuration.c#L169 because this time the configuration does not arrive from a file, rather from a single setting, so the bits that parse a single argument (e.g., https://github.com/agroal/pgagroal/blob/master/src/libpgagroal/configuration.c#L363) should be indepdentt and shared among a file based configuration and a dynamic one.Moreover, not all parameters can be changed at runtime without a restart. My proposal is to use a similar approach at that of a
reloadaction:pgagroal_transfer_configuration(after validation steps).This means that also
pgagrla_reloadfunction https://github.com/agroal/pgagroal/blob/master/src/libpgagroal/configuration.c#L1814 requires refactoring to handle not only a reload driven by a file, but also driven by a single change in the parameters.The text was updated successfully, but these errors were encountered: