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Options are functions of type Option passed as variadic arguments to Dial or DialWithContext. They configure encryption, connection metadata, keepalive behaviour, automatic reconnection, and logging. 
type Option func(*Client)

​
Connection

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WithEncryptionKey

Enables Noise protocol encryption using a base64-encoded 32-byte pre-shared key. The key is the encryption.key value from the api: block of your ESPHome device YAML. 
func WithEncryptionKey(key string) Option
​
key
string
required
Base64-encoded 32-byte Noise PSK from the ESPHome device config.
When this option is set, the client dials a Noise-encrypted transport instead of a plain TCP connection. Omit this option for devices without API encryption enabled. 
client, err := esphome.Dial("mydevice.local:6053", 5*time.Second,
    esphome.WithEncryptionKey("base64encodedkeyhere="),
)

​
WithExpectedName

Sets the device name to validate during the Noise handshake. If the connected device reports a different name, the handshake fails. If empty (the default), no name validation is performed. 
func WithExpectedName(name string) Option
​
name
string
required
The expected device name from the esphome.name field of the device YAML.
client, err := esphome.Dial("mydevice.local:6053", 5*time.Second,
    esphome.WithEncryptionKey("base64encodedkeyhere="),
    esphome.WithExpectedName("living-room-sensor"),
)

​
WithClientInfo

Sets the client_info string sent in the HelloRequest. Useful for identifying your application in ESPHome device logs. 
func WithClientInfo(info string) Option
​
info
string
required
Arbitrary string identifying the client application.
Default: "esphome-apiclient-go" 
esphome.WithClientInfo("my-home-automation-app")

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Keepalive

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WithKeepalive

Configures the interval at which the client sends PingRequest messages to detect stale connections. Set to 0 to disable keepalive entirely. 
func WithKeepalive(interval time.Duration) Option
​
interval
time.Duration
required
Interval between keepalive pings. Set to 0 to disable.
Default: 20 * time.Second 
esphome.WithKeepalive(30 * time.Second)

​
WithKeepaliveTimeout

Configures how long the client waits for a PingResponse before treating the connection as dead. 
func WithKeepaliveTimeout(timeout time.Duration) Option
​
timeout
time.Duration
required
Maximum time to wait for a PingResponse.
Default: 10 * time.Second 
esphome.WithKeepaliveTimeout(5 * time.Second)

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Reconnection

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WithReconnect

Enables automatic reconnection with the given base interval. When the connection drops unexpectedly, the client waits for interval, then attempts to reconnect. If the attempt fails, the delay doubles on each retry (exponential backoff) up to a maximum of 5 minutes. Set to 0 to disable automatic reconnection. After a successful reconnect the client automatically:
  1. Re-discovers entities with ListEntities.
  2. Re-subscribes to state updates if SubscribeStates was called before the drop.
  3. Fires the WithOnConnect callback.
func WithReconnect(interval time.Duration) Option
​
interval
time.Duration
required
Base reconnect interval. The effective delay doubles on each failed attempt, up to 5 minutes.
esphome.WithReconnect(10 * time.Second)

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Callbacks

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WithOnConnect

Registers a callback that fires after the initial connection and after every successful reconnect. 
func WithOnConnect(fn func()) Option
​
fn
func()
required
Called after connection (or reconnection) is established.
esphome.WithOnConnect(func() {
    fmt.Println("device connected")
})

​
WithOnDisconnect

Registers a callback that fires when an unexpected disconnection is detected by the read loop. It does not fire when Close or Disconnect is called intentionally. 
func WithOnDisconnect(fn func()) Option
​
fn
func()
required
Called on unexpected disconnection, before any reconnect attempt.
esphome.WithOnDisconnect(func() {
    fmt.Println("device disconnected unexpectedly")
})

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Logging

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WithLogger

Attaches a custom *log.Logger used by the client to emit diagnostic messages for keepalive failures and reconnect attempts. Without this option, no internal messages are logged. 
func WithLogger(l *log.Logger) Option
​
l
*log.Logger
required
A standard library logger. The client writes keepalive and reconnect messages to it.
logger := log.New(os.Stderr, "[esphome] ", log.LstdFlags)

client, err := esphome.Dial("mydevice.local:6053", 5*time.Second,
    esphome.WithLogger(logger),
    esphome.WithReconnect(10*time.Second),
)

​
Full example

client, err := esphome.DialWithContext(ctx, "mydevice.local:6053", 5*time.Second,
    esphome.WithEncryptionKey("base64encodedkeyhere="),
    esphome.WithExpectedName("mydevice"),
    esphome.WithClientInfo("my-app/1.0"),
    esphome.WithKeepalive(20*time.Second),
    esphome.WithKeepaliveTimeout(10*time.Second),
    esphome.WithReconnect(10*time.Second),
    esphome.WithOnConnect(func() {
        fmt.Println("connected")
    }),
    esphome.WithOnDisconnect(func() {
        fmt.Println("disconnected")
    }),
    esphome.WithLogger(log.New(os.Stderr, "[esphome] ", log.LstdFlags)),
)