Redis plugin for the Salt caching subsystem.
New in version 2017.7.0.
As Redis provides a simple mechanism for very fast key-value store, in order to privde the necessary features for the Salt caching subsystem, the following conventions are used:
minions/alpha is the bank name
stuff is the key name.
- as the caching subsystem is organised as a tree, we need to store the
caching path and identify the bank and its offspring.
At the same time, Redis is linear
and we need to avoid doing
keys <pattern> which is very inefficient
as it goes through all the keys on the remote Redis server.
Instead, each bank hierarchy has a Redis SET associated
which stores the list of sub-banks. By default, these keys begin with
- in addition, each key name is stored in a separate SET
of all the keys within a bank. By default, these SETs begin with
For example, to store the key
my-key under the bank
the following hierarchy will be built:
127.0.0.1:6379> SMEMBERS $BANK_root-bank 1) "sub-bank" 127.0.0.1:6379> SMEMBERS $BANK_root-bank/sub-bank 1) "leaf-bank" 127.0.0.1:6379> SMEMBERS $BANKEYS_root-bank/sub-bank/leaf-bank 1) "my-key" 127.0.0.1:6379> GET $KEY_root-bank/sub-bank/leaf-bank/my-key "my-value"
There are three types of keys stored:
$BANK_*is a Redis SET containing the list of banks under the current bank
$BANKEYS_*is a Redis SET containing the list of keys under the current bank
$KEY_*keeps the value of the key
These prefixes and the separator can be adjusted using the configuration options:
The connection details can be specified using:
Some cluster providers restrict certain redis commands such as CONFIG for enhanced security. Set this option to true to skip checks that required advanced privileges.
Most cloud hosted redis clusters will require this to be set to
The database index.
The database index must be specified as string not as integer value!
Cluster Configuration Example:
Checks if the specified bank contains the specified key.
Fetch data from the Redis cache.
Remove the key from the cache bank with all the key content. If no key is specified, remove the entire bank with all keys and sub-banks inside. This function is using the Redis pipelining for best performance. However, when removing a whole bank, in order to re-create the tree, there are a couple of requests made. In total:
This is not quite optimal, as if we need to flush a bank having a very long list of sub-banks, the number of requests to build the sub-tree may grow quite big.
An improvement for this would be loading a custom Lua script in the Redis instance of the user
register_script feature) and call it whenever we flush.
This script would only need to build this sub-tree causing problems. It can be added later and the behaviour
should not change as the user needs to explicitely allow Salt inject scripts in their Redis instance.
Lists entries stored in the specified bank.
store(bank, key, data)¶
Store the data in a Redis key.