Configuring the Device Connection Service

The Device Connection service provides an implementation of Eclipse Hono™’s Device Connection API.

Protocol adapters use this API to store and retrieve information about the gateway that a device is using to connect to Hono’s protocol adapters. This information is necessary for routing commands to the particular protocol adapter instance that the gateway used by the device is connected to.

The Device Connection component provides a production grade implementation of the Device Connection API which uses a remote data grid for storing information about device connections. The data grid can be scaled out independently from the Device Connection service components to meet the storage demands at hand.

The Device Connection component is implemented as a Spring Boot application. It can be run either directly from the command line or by means of starting the corresponding Docker image created from it.

Service Configuration

The following table provides an overview of the configuration variables and corresponding system properties for configuring the Device Connection component.

The variables only need to be set if the default value does not match your environment.

In addition to the options described in the table above, this component supports the following standard configuration options:

• Common Java VM Options
• Common vert.x Options
• Monitoring Options

Port Configuration

The Device Connection component supports configuration of an AMQP based endpoint that can be configured to listen for connections on

• a secure port only (default) or
• an insecure port only or
• both a secure and an insecure port (dual port configuration)

The server will fail to start if none of the ports is configured properly.

Secure Port Only

The server needs to be configured with a private key and certificate in order to open a TLS secured port.

There are two alternative ways for doing so:

1. Setting the HONO_DEVICECONNECTION_AMQP_KEYSTOREPATH and the HONO_DEVICECONNECTION_AMQP_KEYSTOREPASSWORD variables in order to load the key & certificate from a password protected key store, or
2. setting the HONO_DEVICECONNECTION_AMQP_KEYPATH and HONO_DEVICECONNECTION_AMQP_CERTPATH variables in order to load the key and certificate from two separate PEM files in PKCS8 format.

When starting up, the server will bind a TLS secured socket to the default secure AMQP port 5671. The port number can also be set explicitly using the HONO_DEVICECONNECTION_AMQP_PORT variable.

The HONO_DEVICECONNECTION_AMQP_BINDADDRESS variable can be used to specify the network interface that the port should be exposed on. By default the port is bound to the loopback device only, i.e. the port will only be accessible from the local host. Setting this variable to 0.0.0.0 will let the port being bound to all network interfaces (be careful not to expose the port unintentionally to the outside world).

Insecure Port Only

The secure port will mostly be required for production scenarios. However, it might be desirable to expose a non-TLS secured port instead, e.g. for testing purposes. In any case, the non-secure port needs to be explicitly enabled either by

• explicitly setting HONO_DEVICECONNECTION_AMQP_INSECUREPORT to a valid port number, or by
• implicitly configuring the default AMQP port (5672) by simply setting HONO_DEVICECONNECTION_AMQP_INSECUREPORTENABLED to true.

The server issues a warning on the console if HONO_DEVICECONNECTION_AMQP_INSECUREPORT is set to the default secure AMQP port (5671).

The HONO_DEVICECONNECTION_AMQP_INSECUREPORTBINDADDRESS variable can be used to specify the network interface that the port should be exposed on. By default the port is bound to the loopback device only, i.e. the port will only be accessible from the local host. This variable might be used to e.g. expose the non-TLS secured port on a local interface only, thus providing easy access from within the local network, while still requiring encrypted communication when accessed from the outside over public network infrastructure.

Setting this variable to 0.0.0.0 will let the port being bound to all network interfaces (be careful not to expose the port unintentionally to the outside world).

Dual Port

In test setups and some production scenarios Hono server may be configured to open one secure and one insecure port at the same time.

This is achieved by configuring both ports correctly (see above). The server will fail to start if both ports are configured to use the same port number.

Since the secure port may need different visibility in the network setup compared to the secure port, it has its own binding address HONO_DEVICECONNECTION_AMQP_INSECUREPORTBINDADDRESS. This can be used to narrow the visibility of the insecure port to a local network e.g., while the secure port may be visible worldwide.

Ephemeral Ports

Both the secure as well as the insecure port numbers may be explicitly set to 0. The Device Connection component will then use arbitrary (unused) port numbers determined by the operating system during startup.

Data Grid Connection Configuration

The Device Connection component requires either an embedded cache or a remote data grid, using the Infinispan Hotrod protocol to store device information.

The following table provides an overview of the configuration variables and corresponding system properties for configuring the common aspects of the service:

The type of the cache is selected on startup by enabling or disabling the profile embedded-cache. If the profile is enabled the embedded cache is used, otherwise the remote cache is being used. The remote cache is the default.

Remote cache

The following table provides an overview of the configuration variables and corresponding system properties for configuring the connection to the data grid:

In general, the service supports all configuration properties of the Infinispan Hotrod client using hono.deviceConnection.remote instead of the infinispan.client.hotrod prefix.

Embedded cache

The following table provides an overview of the configuration variables and corresponding system properties for configuring the embedded cache:

Authentication Service Connection Configuration

The Device Connection component requires a connection to an implementation of Hono’s Authentication API in order to authenticate and authorize client requests.

The connection is configured according to the Hono Client Configuration where the ${PREFIX} is set to HONO_AUTH. Since Hono’s Authentication Service does not allow caching of the responses, the cache properties can be ignored.

In addition to the standard client configuration properties, following properties need to be set for the connection:

Metrics Configuration

See Monitoring & Tracing Admin Guide for details on how to configure the reporting of metrics.