Configuring the Command Router Service

The Command Router service provides an implementation of Eclipse Hono™’s Command Router API.

Protocol Adapters use the Command Router API to supply information that the Command Router service component can use to route command & control messages to the particular protocol adapter instances that the target devices are connected to.

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

The Command Router is implemented as a Quarkus application. It can be run either directly from the command line or by means of starting the corresponding Docker image created from it.

Info

The Command Router had originally been implemented as a Spring Boot application. That variant has been deprecated with Hono 1.10.0 and will be completely removed in Hono 2.0.0. The Spring Boot based Docker image will be available until then.

Service Configuration

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

OS Environment Variable
Java System Property
Mandatory Default Description
HONO_APP_MAXINSTANCES
hono.app.maxInstances
no #CPU cores The number of Verticle instances to deploy. If not set, one Verticle per processor core is deployed.
HONO_COMMANDROUTER_AMQP_BINDADDRESS
hono.commandRouter.amqp.bindAddress
no 127.0.0.1 The IP address of the network interface that the secure AMQP port should be bound to.
See Port Configuration below for details.
HONO_COMMANDROUTER_AMQP_CERTPATH
hono.commandRouter.amqp.certPath
no - The absolute path to the PEM file containing the certificate that the server should use for authenticating to clients. This option must be used in conjunction with HONO_COMMANDROUTER_AMQP_KEYPATH.
Alternatively, the HONO_COMMANDROUTER_AMQP_KEYSTOREPATH option can be used to configure a key store containing both the key as well as the certificate.
HONO_COMMANDROUTER_AMQP_INSECUREPORT
hono.commandRouter.amqp.insecurePort
no - The insecure port the server should listen on for AMQP 1.0 connections.
See Port Configuration below for details.
HONO_COMMANDROUTER_AMQP_INSECUREPORTBINDADDRESS
hono.commandRouter.amqp.insecurePortBindAddress
no 127.0.0.1 The IP address of the network interface that the insecure AMQP port should be bound to.
See Port Configuration below for details.
HONO_COMMANDROUTER_AMQP_INSECUREPORTENABLED
hono.commandRouter.amqp.insecurePortEnabled
no false If set to true the server will open an insecure port (not secured by TLS) using either the port number set via HONO_COMMANDROUTER_AMQP_INSECUREPORT or the default AMQP port number (5672) if not set explicitly.
See Port Configuration below for details.
HONO_COMMANDROUTER_AMQP_KEYPATH
hono.commandRouter.amqp.keyPath
no - The absolute path to the (PKCS8) PEM file containing the private key that the server should use for authenticating to clients. This option must be used in conjunction with HONO_COMMANDROUTER_AMQP_CERTPATH. Alternatively, the HONO_COMMANDROUTER_AMQP_KEYSTOREPATH option can be used to configure a key store containing both the key as well as the certificate.
HONO_COMMANDROUTER_AMQP_KEYSTOREPASSWORD
hono.commandRouter.amqp.keyStorePassword
no - The password required to read the contents of the key store.
HONO_COMMANDROUTER_AMQP_KEYSTOREPATH
hono.commandRouter.amqp.keyStorePath
no - The absolute path to the Java key store containing the private key and certificate that the server should use for authenticating to clients. Either this option or the HONO_COMMANDROUTER_AMQP_KEYPATH and HONO_COMMANDROUTER_AMQP_CERTPATH options need to be set in order to enable TLS secured connections with clients. The key store format can be either JKS or PKCS12 indicated by a .jks or .p12 file suffix respectively.
HONO_COMMANDROUTER_AMQP_NATIVETLSREQUIRED
hono.commandRouter.amqp.nativeTlsRequired
no false The server will probe for OpenSSL on startup if a secure port is configured. By default, the server will fall back to the JVM’s default SSL engine if not available. However, if set to true, the server will fail to start at all in this case.
HONO_COMMANDROUTER_AMQP_PORT
hono.commandRouter.amqp.port
no 5671 The secure port that the server should listen on for AMQP 1.0 connections.
See Port Configuration below for details.
HONO_COMMANDROUTER_AMQP_RECEIVERLINKCREDIT
hono.commandRouter.amqp.receiverLinkCredit
no 100 The number of credits to flow to a client connecting to the service’s AMQP endpoint.
HONO_COMMANDROUTER_AMQP_SECUREPROTOCOLS
hono.commandRouter.amqp.secureProtocols
no TLSv1.3,TLSv1.2 A (comma separated) list of secure protocols (in order of preference) that are supported when negotiating TLS sessions. Please refer to the vert.x documentation for a list of supported protocol names.
HONO_COMMANDROUTER_AMQP_SUPPORTEDCIPHERSUITES
hono.commandRouter.amqp.supportedCipherSuites
no - A (comma separated) list of names of cipher suites (in order of preference) that are supported when negotiating TLS sessions. Please refer to JSSE Cipher Suite Names for a list of supported names.
HONO_COMMANDROUTER_SVC_KUBERNETESBASEDADAPTERINSTANCESTATUSSERVICEENABLED
hono.commandRouter.svc.kubernetesBasedAdapterInstanceStatusServiceEnabled
no true If set to true and the Command Router component runs in a Kubernetes cluster, a Kubernetes based service to identify protocol adapter instances will be used to prevent sending command & control messages to already terminated adapter instances. Needs to be set to false if not all protocol adapters are part of the Kubernetes cluster and namespace that the Command Router component is in.

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:

Port Configuration

The Command Router 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_COMMANDROUTER_AMQP_KEYSTOREPATH and the HONO_COMMANDROUTER_AMQP_KEYSTOREPASSWORD variables in order to load the key & certificate from a password protected key store, or
  2. setting the HONO_COMMANDROUTER_AMQP_KEYPATH and HONO_COMMANDROUTER_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_COMMANDROUTER_AMQP_PORT variable.

The HONO_COMMANDROUTER_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_COMMANDROUTER_AMQP_INSECUREPORT to a valid port number, or by
  • implicitly configuring the default AMQP port (5672) by simply setting HONO_COMMANDROUTER_AMQP_INSECUREPORTENABLED to true.

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

The HONO_COMMANDROUTER_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_COMMANDROUTER_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 Command Router component will then use arbitrary (unused) port numbers determined by the operating system during startup.

Messaging Configuration

The Command Router component uses a connection to an AMQP 1.0 Messaging Network and/or an Apache Kafka cluster to

  • receive command & control messages sent by downstream applications and to forward these commands on a specific address/topic so that they can be received by protocol adapters,
  • send delivery failure command response messages in case no consumer exists for a received command (only with Kafka messaging),
  • receive notification messages about changes to tenant/device/credentials data sent from the device registry.

Command messages are received on each configured messaging system.

For notification messages, the Kafka connection is used by default, if configured. Otherwise the AMQP messaging network is used.

AMQP 1.0 Messaging Network Connection Configuration

The connection to the AMQP 1.0 Messaging Network is configured according to the Hono Client Configuration with HONO_COMMAND being used as ${PREFIX}. The properties for configuring response caching can be ignored.

Kafka based Messaging Configuration

The connection to an Apache Kafka cluster can be configured according to the Hono Kafka Client Configuration.

The following table provides an overview of the prefixes to be used to individually configure the Kafka clients used by the component. The individual client configuration is optional, a minimal configuration may only contain a common client configuration consisting of properties prefixed with HONO_KAFKA_COMMONCLIENTCONFIG_ and hono.kafka.commonClientConfig. respectively.

OS Environment Variable Prefix
Java System Property Prefix
Description
HONO_KAFKA_CLEANUP_ADMINCLIENTCONFIG_
hono.kafka.cleanup.adminClientConfig.
Configures the Kafka admin client that removes Hono internal topics.
HONO_KAFKA_COMMAND_CONSUMERCONFIG_
hono.kafka.command.consumerConfig.
Configures the Kafka consumer that receives command messages.
HONO_KAFKA_COMMANDINTERNAL_PRODUCERCONFIG_
hono.kafka.commandInternal.producerConfig.
Configures the Kafka producer that publishes command messages to Hono internal topics.
HONO_KAFKA_COMMANDRESPONSE_PRODUCERCONFIG_
hono.kafka.commandResponse.producerConfig.
Configures the Kafka producer that publishes command response messages.
HONO_KAFKA_NOTIFICATION_CONSUMERCONFIG_
hono.kafka.notification.consumerConfig.
Configures the Kafka consumer that receives notification messages about changes to tenant/device/credentials data.

Tenant Service Connection Configuration

The Command Router component requires a connection to an implementation of Hono’s Tenant API in order to retrieve information for a tenant.

The connection to the Tenant Service is configured according to the Hono Client Configuration where the ${PREFIX} is set to HONO_TENANT and the additional values for response caching apply.

The adapter caches the responses from the service according to the cache directive included in the response. If the response doesn’t contain a cache directive no data will be cached.

Device Registration Service Connection Configuration

The Command Router component requires a connection to an implementation of Hono’s Device Registration API in order to retrieve registration status assertions for the target devices of incoming command messages.

The connection to the Device Registration Service is configured according to the Hono Client Configuration where the ${PREFIX} is set to HONO_REGISTRATION.

The adapter caches the responses from the service according to the cache directive included in the response. If the response doesn’t contain a cache directive no data will be cached.

Note that the adapter uses a single cache for all responses from the service regardless of the tenant identifier. Consequently, the Device Registration Service client configuration’s responseCacheMinSize and responseCacheMaxSize properties determine the overall number of responses that can be cached.

Data Grid Connection Configuration

The Command Router 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 command line options for configuring the common aspects of the service:

OS Environment Variable
Java System Property
Mandatory Default Description
HONO_COMMANDROUTER_CACHE_COMMON_CACHENAME
hono.commandRouter.cache.common.cacheName
no command-router The name of the cache
HONO_COMMANDROUTER_CACHE_COMMON_CHECKKEY
hono.commandRouter.cache.common.checkKey
no KEY_CONNECTION_CHECK The key used to check the health of the cache. This is only used in case of a remote cache.
HONO_COMMANDROUTER_CACHE_COMMON_CHECKVALUE
hono.commandRouter.cache.common.checkValue
no VALUE_CONNECTION_CHECK The value used to check the health of the cache. This is only used in case of a remote cache.

The type of cache (embedded or remote) is determined during startup by means of the HONO_COMMANDROUTER_CACHE_REMOTE_SERVERLIST configuration variable. If the variable has a non empty value, a remote cache is configured. Otherwise, an embedded cache is configured.

Remote cache

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

OS Environment Variable
Java System Property
Mandatory Default Description
HONO_COMMANDROUTER_CACHE_REMOTE_SERVERLIST
hono.commandRouter.cache.remote.serverList
yes - A list of remote servers in the form: host1[:port][;host2[:port]].....
HONO_COMMANDROUTER_CACHE_REMOTE_AUTHSERVERNAME
hono.commandRouter.cache.remote.authServerName
yes - The server name to indicate in the SASL handshake when authenticating to the server.
HONO_COMMANDROUTER_CACHE_REMOTE_AUTHREALM
hono.commandRouter.cache.remote.authRealm
yes - The authentication realm for the SASL handshake when authenticating to the server.
HONO_COMMANDROUTER_CACHE_REMOTE_AUTHUSERNAME
hono.commandRouter.cache.remote.authUsername
yes - The username to use for authenticating to the server.
HONO_COMMANDROUTER_CACHE_REMOTE_AUTHPASSWORD
hono.commandRouter.cache.remote.authPassword
yes - The password to use for authenticating to the server.
HONO_COMMANDROUTER_CACHE_REMOTE_SASLMECHANISM
hono.commandRouter.cache.remote.saslMechanism
yes - The SASL mechanism to use for authenticating to the server.
HONO_COMMANDROUTER_CACHE_REMOTE_CLUSTER_[*]
hono.commandRouter.cache.remote.cluster.[*]
no - Alternate cluster definition. Example:
Property: hono.commandRouter.cache.remote.cluster.siteA, value: hostA1:11222;hostA2:11223.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_EXHAUSTEDACTION
hono.commandRouter.cache.remote.connectionPool.exhaustedAction
no WAIT Specifies what happens when asking for a connection from a server’s pool, and that pool is exhausted. Valid values are WAIT, CREATE_NEW and EXCEPTION.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_MAXACTIVE
hono.commandRouter.cache.remote.connectionPool.maxActive
no -1 (no limit) Maximum number of connections per server.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_MAXPENDINGREQUESTS
hono.commandRouter.cache.remote.connectionPool.maxPendingRequests
no -1 (no limit) Specifies the maximum number of requests sent over a single connection at one instant.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_MAXWAIT
hono.commandRouter.cache.remote.connectionPool.maxWait
no -1 (no limit) Time to wait in milliseconds for a connection to become available if exhaustedAction is WAIT.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_MINEVICTABLEIDLETIME
hono.commandRouter.cache.remote.connectionPool.minEvictableIdleTime
no -1 (no limit) Minimum amount of time that an connection may sit idle in the pool.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTIONPOOL_MINIDLE
hono.commandRouter.cache.remote.connectionPool.minIdle
no -1 (no limit) Minimum number of idle connections (per server) that should always be available.
HONO_COMMANDROUTER_CACHE_REMOTE_CONNECTTIMEOUT
hono.commandRouter.cache.remote.connectTimeout
no 60000 The timeout for connections in milliseconds.
HONO_COMMANDROUTER_CACHE_REMOTE_DEFAULTEXECUTORFACTORY_POOLSIZE
hono.commandRouter.cache.remote.defaultExecutorFactory.poolSize
no 99 Size of the thread pool.
HONO_COMMANDROUTER_CACHE_REMOTE_DEFAULTEXECUTORFACTORY_THREADNAMEPREFIX
hono.commandRouter.cache.remote.defaultExecutorFactory.threadnamePrefix
no HotRod-client-async-pool Prefix for the default executor thread names.
HONO_COMMANDROUTER_CACHE_REMOTE_DEFAULTEXECUTORFACTORY_THREADNAMESUFFIX
hono.commandRouter.cache.remote.defaultExecutorFactory.threadnameSuffix
no - Suffix for the default executor thread names.
HONO_COMMANDROUTER_CACHE_REMOTE_KEYALIAS
hono.commandRouter.cache.remote.keyAlias
no - The alias of the key to use, in case the keyStore contains multiple certificates.
HONO_COMMANDROUTER_CACHE_REMOTE_KEYSTORECERTIFICATEPASSWORD
hono.commandRouter.cache.remote.keyStoreCertificatePassword
no - The certificate password in the keystore.
HONO_COMMANDROUTER_CACHE_REMOTE_KEYSTOREFILENAME
hono.commandRouter.cache.remote.keyStoreFileName
no - The filename of a keystore to use when using client certificate authentication.
HONO_COMMANDROUTER_CACHE_REMOTE_KEYSTOREPASSWORD
hono.commandRouter.cache.remote.keyStorePassword
no - The keystore password.
HONO_COMMANDROUTER_CACHE_REMOTE_KEYSTORETYPE
hono.commandRouter.cache.remote.keyStoreType
no JKS The keystore type.
HONO_COMMANDROUTER_CACHE_REMOTE_SASLPROPERTIES_[*]
hono.commandRouter.cache.remote.saslProperties.[*]
no - A SASL property (specific to the used SASL mechanism).
HONO_COMMANDROUTER_CACHE_REMOTE_SOCKETTIMEOUT
hono.commandRouter.cache.remote.socketTimeout
no 60000 The timeout for socket read/writes in milliseconds.
HONO_COMMANDROUTER_CACHE_REMOTE_SSLCIPHERS
hono.commandRouter.cache.remote.sslCiphers
no - A list of ciphers, separated with spaces and in order of preference, that are used during the SSL handshake to negotiate a cryptographic algorithm for key encryption. By default, the SSL protocol (e.g. TLSv1.2) determines which ciphers to use. You should customize the cipher list with caution to avoid vulnerabilities from weak algorithms. For details about cipher lists and possible values, refer to the OpenSSL documentation.
HONO_COMMANDROUTER_CACHE_REMOTE_SSLPROTOCOL
hono.commandRouter.cache.remote.sslProtocol
no - The SSL protocol to use (e.g. TLSv1.2).
HONO_COMMANDROUTER_CACHE_REMOTE_TRUSTSTOREFILENAME
hono.commandRouter.cache.remote.trustStoreFileName
no - The path of the trust store.
HONO_COMMANDROUTER_CACHE_REMOTE_TRUSTSTOREPASSWORD
hono.commandRouter.cache.remote.trustStorePassword
no - The password of the trust store.
HONO_COMMANDROUTER_CACHE_REMOTE_TRUSTSTORETYPE
hono.commandRouter.cache.remote.trustStoreType
no JKS The type of the trust store. Valid values are JKS, JCEKS, PCKS12 and PEM.
HONO_COMMANDROUTER_CACHE_REMOTE_USESSL
hono.commandRouter.cache.remote.useSSL
no false Enable TLS (implicitly enabled if a trust store is set).

See also the Infinispan Hotrod client documentation.

Embedded cache

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

OS Environment Variable
Java System Property
Mandatory Default Description
HONO_COMMANDROUTER_CACHE_EMBEDDED_CONFIGURATIONFILE
hono.commandRouter.cache.embedded.configurationFile
yes - The absolute path to an Infinispan configuration file. Also see the Infinispan Configuration Schema.

Authentication Service Connection Configuration

The Command Router 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:

OS Environment Variable
Java System Property
Mandatory Default Description
HONO_AUTH_VALIDATION_CERTPATH
hono.auth.validation.certPath
no - The absolute path to the PEM file containing the public key that the service should use for validating tokens issued by the Authentication service. Alternatively, a symmetric key can be used for validating tokens by setting the HONO_AUTH_VALIDATION_SHAREDSECRET variable. If none of these variables is set, the service falls back to the key indicated by the HONO_AUTH_CERTPATH variable. If that variable is also not set, startup of the service fails.
HONO_AUTH_VALIDATION_SHAREDSECRET
hono.auth.validation.sharedSecret
no - A string to derive a symmetric key from which is used for validating tokens issued by the Authentication service. The key is derived from the string by using the bytes of the String’s UTF8 encoding. When setting the validation key using this variable, the Authentication service must be configured with the same key. Alternatively, an asymmetric key pair can be used for validating (and signing) by setting the HONO_AUTH_SIGNING_CERTPATH variable. If none of these variables is set, startup of the service fails.

Metrics Configuration

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