Unified Quota (unified-quota) Plugin

Unified quota plugin is a combined count and dict plugin, which uses quota:count to keep tabs of local quota and dict lookups to maintain external usage. When quota usage is looked up, it will count local quota usage and increment that with the other product(s) in dict.

Note

Unified Quota requires Cassandra.

Cassandra Schema

The unified quota schema:

CREATE KEYSPACE IF NOT EXISTS quota
  WITH REPLICATION = { 'class': 'SimpleStrategy', 'replication_factor': '1' } 
  AND durable_writes = true;

USE quota;
CREATE TABLE quota.quota_usage (
    ox_id text,
    type text,
    count bigint,
    usage bigint,
    PRIMARY KEY (ox_id, type)
  ) WITH CLUSTERING ORDER BY (type ASC)
  AND bloom_filter_fp_chance = 0.01
  AND caching = { 'keys':'ALL', 'rows_per_partition':'NONE' }
  AND comment = ''
  AND compaction = { 'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy' }
  AND compression = { 'sstable_compression': 'org.apache.cassandra.io.compress.LZ4Compressor' }
  AND dclocal_read_repair_chance = 0.1
  AND default_time_to_live = 0
  AND gc_grace_seconds = 864000
  AND max_index_interval = 2048
  AND memtable_flush_period_in_ms = 0
  AND min_index_interval = 128
  AND read_repair_chance = 0.0
  AND speculative_retry = '99.0PERCENTILE';

Create the unified quota schema in Cassandra:

cqlsh < unified_quota_scheme.cql

Create a dovecot-dict-cql.conf.ext file and change the host= to your Cassandra hosts address. If you named the keyspace differently also configure it via dbname=.

connect = host=1.2.3.4 dbname=quota

map {
  pattern = priv/quota/messages/$product
  table = quota_usage
  username_field = ox_id
  value_field = count
  value_type = uint
  fields {
    type = $product
  }
}

map {
  pattern = priv/quota/storage/$product
  table = quota_usage
  username_field = ox_id
  value_field = usage
  value_type = uint
  fields {
    type = $product
  }
}

In your dovecot.conf you must enable the quota_unified plugin and configure the dict service with the dovecot-dict-cql.conf.ext path:

# Add dict-async socket which provides access to cassandra
service dict-async {
  unix_listener dict-async {
    user = vmail
  }
  vsz_limit = 0
}

# Add "service dict" for dovecot-dict-cql.conf.ext integration
service dict {
  unix_listener dict {
    mode = 0600
    user = vmail
  }
  vsz_limit = 0
}

# Add the Cassandra mappings
dict {
  cassandra = cassandra:/etc/dovecot/dovecot-dict-cql.conf.ext
}

# Add "quota_unified" to your mail_plugins
mail_plugins = $mail_plugins quota_unified

# Add the unified quota plugin (configured to use Cassandra "dict" driver)
plugin {
  quota = unified:User quota::no-unset:proxy:dict-async:cassandra
}