salt.cache.redis_cache¶

Redis¶

Redis plugin for the Salt caching subsystem.

To enable this cache plugin, the master will need the python client for redis installed. This can be easily installed with pip:

salt \* pip.install redis

As Redis provides a simple mechanism for very fast key-value store, in order to provide the necessary features for the Salt caching subsystem, the following conventions are used:

• A Redis key consists of the bank name and the cache key separated by /, e.g.: $KEY_minions/alpha/stuff where minions/alpha is the bank name and 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 $BANK_.

• In addition, each key name is stored in a separate SET of all the keys within a bank. By default, these SETs begin with $BANKEYS_.

For example, to store the key my-key under the bank root-bank/sub-bank/leaf-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 four 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.

• $TSTAMP_* stores the last updated timestamp of the key.

These prefixes and the separator can be adjusted using the configuration options:

bank_prefix: $BANK

The prefix used for the name of the Redis key storing the list of sub-banks.

bank_keys_prefix: $BANKEYS

The prefix used for the name of the Redis key storing the list of keys under a certain bank.

key_prefix: $KEY

The prefix of the Redis keys having the value of the keys to be cached under a certain bank.

timestamp_prefix: $TSTAMP

The prefix for the last modified timestamp for keys.

New in version 3005.

separator: _

The separator between the prefix and the key body.

The connection details can be specified using:

host: localhost

The hostname of the Redis server.

port: 6379

The Redis server port.

cluster_mode: False

Whether cluster_mode is enabled or not

cluster.startup_nodes:

A list of host, port dictionaries pointing to cluster members. At least one is required but multiple nodes are better

cache.redis.cluster.startup_nodes
  - host: redis-member-1
    port: 6379
  - host: redis-member-2
    port: 6379

cluster.skip_full_coverage_check: False

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.

Note

Most cloud hosted redis clusters will require this to be set to True

db: '0'

The database index.

Note

The database index must be specified as string not as integer value!

password:

Redis connection password.

unix_socket_path:

New in version 2018.3.1.

Path to a UNIX socket for access. Overrides host / port.

Configuration Example:

cache.redis.host: localhost
cache.redis.port: 6379
cache.redis.db: '0'
cache.redis.password: my pass
cache.redis.bank_prefix: #BANK
cache.redis.bank_keys_prefix: #BANKEYS
cache.redis.key_prefix: #KEY
cache.redis.timestamp_prefix: #TICKS
cache.redis.separator: '@'

Cluster Configuration Example:

cache.redis.cluster_mode: true
cache.redis.cluster.skip_full_coverage_check: true
cache.redis.cluster.startup_nodes:
  - host: redis-member-1
    port: 6379
  - host: redis-member-2
    port: 6379
cache.redis.db: '0'
cache.redis.password: my pass
cache.redis.bank_prefix: #BANK
cache.redis.bank_keys_prefix: #BANKEYS
cache.redis.key_prefix: #KEY
cache.redis.separator: '@'