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This project is a Redis adapter forYggdrasil publisher/subscriber.

The following example uses Redis adapter to distribute messages:

iex(1)>channel=%Yggdrasil.Channel{name:"some_channel",adapter::redis}iex(2)>Yggdrasil.subscribe(channel)iex(3)>flush(){:Y_CONNECTED,%Yggdrasil.Channel{(...)}}

and to publish a message for the subscribers:

iex(4)>Yggdrasil.publish(channel,"message")iex(5)>flush(){:Y_EVENT,%Yggdrasil.Channel{(...)},"message"}

When the subscriber wants to stop receiving messages, then it can unsubscribefrom the channel:

iex(6)>Yggdrasil.unsubscribe(channel)iex(7)>flush(){:Y_DISCONNECTED,%Yggdrasil.Channel{(...)}}

The Redis adapter has the following rules:

• Theadapter name is identified by the atom:redis.
• The channelname must be a string.
• Thetransformer must encode to a string. From thetransformers providedit defaults to:default, but:json can also be used.
• Anybackend can be used (by default is:default).

The following is an example of a valid channel for both publishers andsubscribers:

%Yggdrasil.Channel{name:"redis_channel_name",adapter::redis,transformer::json}

It will expect valid JSONs from Redis and it will write valid JSONs in Redis.

Uses the list of options forRedix, but the more relevant optuons are shownbelow:

• hostname - Redis hostname (defaults to"localhost").
• port - Redis port (defaults to6379).
• password - Redis password (defaults to"").

The following shows a configuration with and without namespace:

# Without namespaceconfig:yggdrasil,redis:[hostname:"redis.zero"]# With namespaceconfig:yggdrasil,RedisOne,redis:[hostname:"redis.one",port:1234]

Also the options can be provided as OS environment variables. The availablevariables are:

• YGGDRASIL_REDIS_HOSTNAME or<NAMESPACE>_YGGDRASIL_REDIS_HOSTNAME.
• YGGDRASIL_REDIS_PORT or<NAMESPACE>_YGGDRASIL_REDIS_PORT.
• YGGDRASIL_REDIS_PASSWORD or<NAMESPACE>_YGGDRASIL_REDIS_PASSWORD.
• YGGDRASIL_REDIS_DATABASE or<NAMESPACE>_YGGDRASIL_REDIS_DATABASE.

where<NAMESPACE> is the snakecase of the namespace chosen e.g. for thenamespaceRedisTwo, you would useREDIS_TWO as namespace in the OSenvironment variable.

Using this Redis adapter withYggdrasil is a matter of adding the availablehex package to yourmix.exs file e.g:

defdepsdo[{:yggdrasil_redis,"~> 4.1"}]end

Adocker-compose.yml file is provided with the project. If you don't have aRedis database, but you do have Docker installed, then just do:

$ docker-compose up --build

And in another shell run:

$ mix deps.get$ mix test

• Redix.PubSub: Redis pubsub.

Alexander de Sousa.

Yggdrasil is released under the MIT License. See the LICENSE file for furtherdetails.