# Problem
Some redis modules need to call `CONFIG GET/SET` commands. Server may be
ran with `rename-command CONFIG ""`(or something similar) which leads to
the module being unable to access the config.
# Solution
Added new API functions for use by modules
```
RedisModuleConfigIterator* RedisModule_GetConfigIterator(RedisModuleCtx *ctx, const char *pattern);
void RedisModule_ReleaseConfigIterator(RedisModuleCtx *ctx, RedisModuleConfigIterator *iter);
const char *RedisModule_ConfigIteratorNext(RedisModuleConfigIterator *iter);
int RedisModule_GetConfigType(const char *name, RedisModuleConfigType *res);
int RedisModule_GetBoolConfig(RedisModuleCtx *ctx, const char *name, int *res);
int RedisModule_GetConfig(RedisModuleCtx *ctx, const char *name, RedisModuleString **res);
int RedisModule_GetEnumConfig(RedisModuleCtx *ctx, const char *name, RedisModuleString **res);
int RedisModule_GetNumericConfig(RedisModuleCtx *ctx, const char *name, long long *res);
int RedisModule_SetBoolConfig(RedisModuleCtx *ctx, const char *name, int value, RedisModuleString **err);
int RedisModule_SetConfig(RedisModuleCtx *ctx, const char *name, RedisModuleString *value, RedisModuleString **err);
int RedisModule_SetEnumConfig(RedisModuleCtx *ctx, const char *name, RedisModuleString *value, RedisModuleString **err);
int RedisModule_SetNumericConfig(RedisModuleCtx *ctx, const char *name, long long value, RedisModuleString **err);
```
## Implementation
The work is mostly done inside `config.c` as I didn't want to expose the
config dict outside of it. That means each of these module functions has
a corresponding method in `config.c` that actually does the job. F.e
`RedisModule_SetEnumConfig` calls `moduleSetEnumConfig` which is
implemented in `config.c`
## Notes
Also, refactored `configSetCommand` and `restoreBackupConfig` functions
for the following reasons:
- code and logic is now way more clear in `configSetCommand`. Only
caveat here is removal of an optimization that skipped running apply
functions that already have ran in favour of code clarity.
- Both functions needlessly separated logic for module configs and
normal configs whereas no such separation is needed. This also had the
side effect of removing some allocations.
- `restoreBackupConfig` now has clearer interface and can be reused with
ease. One of the places I reused it is for the individual
`moduleSet*Config` functions, each of which needs the restoration
functionality but for a single config only.
## Future
Additionally, a couple considerations were made for potentially
extending the API in the future
- if need be an API for atomically setting multiple config values can be
added - `RedisModule_SetConfigsTranscationStart/End` or similar that can
be put around `RedisModule_Set*Config` calls.
- if performance is an issue an API
`RedisModule_GetConfigIteratorNextWithTypehint` or similar may be added
in order not to incur the additional cost of calling
`RedisModule_GetConfigType`.
---------
Co-authored-by: Oran Agra <oran@redislabs.com>
Mincho Paskalev