redis

Redis is the implementation of the key-value Data Broker client API for the Redis key-value data store. See cn-infra/db/keyval for the definition of the key-value Data Broker client API.

The entity BytesConnectionRedis provides access to CRUD as well as event subscription API's.

   +-----+   (Broker)   +------------------------+ -->  CRUD      +-------+ -->
   | app |                   |  BytesConnectionRedis  |                 | Redis |
   +-----+    <-- (KeyValProtoWatcher)  +------------------------+  <--  events    +-------+

How to use Redis

The code snippets below provide examples to help you get started. For simplicity, error handling is omitted.

Need to import following dependencies

    import "github.com/ligato/cn-infra/db/keyval/kvproto"
    import "github.com/ligato/cn-infra/db/keyval/redis"
    import "github.com/ligato/cn-infra/utils/config"
    import "github.com/ligato/cn-infra/logging/logrus"

Define client configuration based on your Redis installation.

• Single Node var cfg redis.NodeConfig
• Sentinel Enabled Cluster var cfg redis.SentinelConfig
• Redis Cluster var cfg redis.ClusterConfig
• See sample YAML configurations (*.yaml files)

You can initialize any of the above configuration instances in memory, or load the settings from file using

   err = config.ParseConfigFromYamlFile(configFile, &cfg)

You can also load any of the three configuration files using

   var cfg interface{}
   cfg, err := redis.LoadConfig(configFile)

Create connection from configuration

   client, err := redis.CreateClient(cfg)
   db, err := redis.NewBytesConnection(client, logrus.DefaultLogger())

Create Brokers / Watchers from connection

   //create broker/watcher that share the same connection pools.
   bytesBroker := db.NewBroker("some-prefix")
   bytesWatcher := db.NewWatcher("some-prefix")

   // create broker/watcher that share the same connection pools,
   // capable of processing protocol-buffer generated data.
   wrapper := kvproto.NewProtoWrapper(db)
   protoBroker := wrapper.NewBroker("some-prefix")
   protoWatcher := wrapper.NewWatcher("some-prefix")

Perform CRUD operations

   // put
   err = db.Put("some-key", []byte("some-value"))
   err = db.Put("some-temp-key", []byte("valid for 20 seconds"),
                 datasync.WithTTL(20*time.Second))

   // get
   value, found, revision, err := db.GetValue("some-key")
   if found {
       ...
   }

   // Note: flight.Info implements proto.Message.
   f := flight.Info{
           Airline:  "UA",
           Number:   1573,
           Priority: 1,
        }
   err = protoBroker.Put("some-key-prefix", &f)
   f2 := flight.Info{}
   found, revision, err = protoBroker.GetValue("some-key-prefix", &f2)

   // list
   keyPrefix := "some"
   kv, err := db.ListValues(keyPrefix)
   for {
       kv, done := kv.GetNext()
       if done {
           break
       }
        key := kv.GetKey()
       value := kv.GetValue()
   }

   // delete
   found, err := db.Delete("some-key")
   // or, delete all keys matching the prefix "some-key".
   found, err := db.Delete("some-key", datasync.WithPrefix())

   // transaction
   var txn keyval.BytesTxn = db.NewTxn()
   txn.Put("key101", []byte("val 101")).Put("key102", []byte("val 102"))
   txn.Put("key103", []byte("val 103")).Put("key104", []byte("val 104"))
   err := txn.Commit()

Subscribe to key space events

   watchChan := make(chan keyval.BytesWatchResp, 10)
   err = db.Watch(watchChan, "some-key")
   for {
       select {
        case r := <-watchChan:
           switch r.GetChangeType() {
           case datasync.Put:
               log.Infof("KeyValProtoWatcher received %v: %s=%s", r.GetChangeType(),
                         r.GetKey(), string(r.GetValue()))
           case datasync.Delete:
               ...
           }
       ...
       }
  }

NOTE: You must configure Redis for it to publish key space events.

   config SET notify-keyspace-events KA

See EVENT NOTIFICATION for more details.

You can find detailed examples in

• simple
• airport

Resiliency

Connection/read/write time-outs, failover, reconnection and recovery are validated by running the airport example against a Redis Sentinel Cluster. Redis nodes are paused selectively to simulate server down:

$ docker-compose ps

Name	Command	State	Ports
dockerredissentinel_master_1	docker-entrypoint.sh redis ...	Paused	6379/tcp
dockerredissentinel_slave_1	docker-entrypoint.sh redis ...	Up	6379/tcp
dockerredissentinel_slave_2	docker-entrypoint.sh redis ...	Up	6379/tcp
dockerredissentinel_sentinel_1	sentinel-entrypoint.sh	Up	26379/tcp, 6379/tcp
dockerredissentinel_sentinel_2	sentinel-entrypoint.sh	Up	26379/tcp, 6379/tcp
dockerredissentinel_sentinel_3	sentinel-entrypoint.sh	Up	26379/tcp, 6379/tcp