coap

README

Magistrala CoAP Adapter

Magistrala CoAP adapter provides an CoAP API for sending messages through the platform.

Configuration

The service is configured using the environment variables presented in the following table. Note that any unset variables will be replaced with their default values.

Variable	Description	Default
MG_COAP_ADAPTER_LOG_LEVEL	Log level for the CoAP Adapter (debug, info, warn, error)	info
MG_COAP_ADAPTER_HOST	CoAP service listening host	""
MG_COAP_ADAPTER_PORT	CoAP service listening port	5683
MG_COAP_ADAPTER_SERVER_CERT	CoAP service server certificate	""
MG_COAP_ADAPTER_SERVER_KEY	CoAP service server key	""
MG_COAP_ADAPTER_HTTP_HOST	Service HTTP listening host	""
MG_COAP_ADAPTER_HTTP_PORT	Service listening port	5683
MG_COAP_ADAPTER_HTTP_SERVER_CERT	Service server certificate	""
MG_COAP_ADAPTER_HTTP_SERVER_KEY	Service server key	""
MG_THINGS_AUTH_GRPC_URL	Things service Auth gRPC URL	localhost:7000
MG_THINGS_AUTH_GRPC_TIMEOUT	Things service Auth gRPC request timeout in seconds	1s
MG_THINGS_AUTH_GRPC_CLIENT_CERT	Path to the PEM encoded things service Auth gRPC client certificate file	""
MG_THINGS_AUTH_GRPC_CLIENT_KEY	Path to the PEM encoded things service Auth gRPC client key file	""
MG_THINGS_AUTH_GRPC_SERVER_CERTS	Path to the PEM encoded things server Auth gRPC server trusted CA certificate file	""
MG_MESSAGE_BROKER_URL	Message broker instance URL	nats://localhost:4222
MG_JAEGER_URL	Jaeger server URL	http://localhost:14268/api/traces
MG_JAEGER_TRACE_RATIO	Jaeger sampling ratio	1.0
MG_SEND_TELEMETRY	Send telemetry to magistrala call home server	true
MG_COAP_ADAPTER_INSTANCE_ID	CoAP adapter instance ID	""

Deployment

The service itself is distributed as Docker container. Check the coap-adapter service section in docker-compose to see how service is deployed.

Running this service outside of container requires working instance of the message broker service, things service and Jaeger server. To start the service outside of the container, execute the following shell script:

# download the latest version of the service
git clone https://github.com/absmach/magistrala

cd magistrala

# compile the http
make coap

# copy binary to bin
make install

# set the environment variables and run the service
MG_COAP_ADAPTER_LOG_LEVEL=info \
MG_COAP_ADAPTER_HOST=localhost \
MG_COAP_ADAPTER_PORT=5683 \
MG_COAP_ADAPTER_SERVER_CERT="" \
MG_COAP_ADAPTER_SERVER_KEY="" \
MG_COAP_ADAPTER_HTTP_HOST=localhost \
MG_COAP_ADAPTER_HTTP_PORT=5683 \
MG_COAP_ADAPTER_HTTP_SERVER_CERT="" \
MG_COAP_ADAPTER_HTTP_SERVER_KEY="" \
MG_THINGS_AUTH_GRPC_URL=localhost:7000 \
MG_THINGS_AUTH_GRPC_TIMEOUT=1s \
MG_THINGS_AUTH_GRPC_CLIENT_CERT="" \
MG_THINGS_AUTH_GRPC_CLIENT_KEY="" \
MG_THINGS_AUTH_GRPC_SERVER_CERTS="" \
MG_MESSAGE_BROKER_URL=nats://localhost:4222 \
MG_JAEGER_URL=http://localhost:14268/api/traces \
MG_JAEGER_TRACE_RATIO=1.0 \
MG_SEND_TELEMETRY=true \
MG_COAP_ADAPTER_INSTANCE_ID="" \
$GOBIN/magistrala-coap

Setting MG_COAP_ADAPTER_SERVER_CERT and MG_COAP_ADAPTER_SERVER_KEY will enable TLS against the service. The service expects a file in PEM format for both the certificate and the key. Setting MG_COAP_ADAPTER_HTTP_SERVER_CERT and MG_COAP_ADAPTER_HTTP_SERVER_KEY will enable TLS against the service. The service expects a file in PEM format for both the certificate and the key.

Setting MG_THINGS_AUTH_GRPC_CLIENT_CERT and MG_THINGS_AUTH_GRPC_CLIENT_KEY will enable TLS against the things service. The service expects a file in PEM format for both the certificate and the key. Setting MG_THINGS_AUTH_GRPC_SERVER_CERTS will enable TLS against the things service trusting only those CAs that are provided. The service expects a file in PEM format of trusted CAs.

Usage

If CoAP adapter is running locally (on default 5683 port), a valid URL would be: coap://localhost/channels/<channel_id>/messages?auth=<thing_auth_key>. Since CoAP protocol does not support Authorization header (option) and options have limited size, in order to send CoAP messages, valid auth value (a valid Thing key) must be present in Uri-Query option.

Documentation

Overview

Package coap contains the domain concept definitions needed to support Magistrala CoAP adapter service functionality. All constant values are taken from RFC, and could be adjusted based on specific use case.

Index

• Variables
• type Client
  • func NewClient(c mux.Client, tkn message.Token, l *slog.Logger) Client
• type Service
  • func New(authClient magistrala.AuthzServiceClient, pubsub messaging.PubSub) Service

Variables

var ErrOption = errors.New("unable to set option")

ErrOption indicates an error when adding an option.

var ErrUnsubscribe = errors.New("unable to unsubscribe")

ErrUnsubscribe indicates an error to unsubscribe.

Types

type Client

type Client interface {
	// In CoAP terminology, Token similar to the Session ID.
	Token() string

	// Handle handles incoming messages.
	Handle(m *messaging.Message) error

	// Cancel cancels the client.
	Cancel() error

	// Done returns a channel that's closed when the client is done.
	Done() <-chan struct{}
}

Client wraps CoAP client.

func NewClient

func NewClient(c mux.Client, tkn message.Token, l *slog.Logger) Client

NewClient instantiates a new Observer.

type Service

type Service interface {
	// Publish publishes message to specified channel.
	// Key is used to authorize publisher.
	Publish(ctx context.Context, key string, msg *messaging.Message) error

	// Subscribes to channel with specified id, subtopic and adds subscription to
	// service map of subscriptions under given ID.
	Subscribe(ctx context.Context, key, chanID, subtopic string, c Client) error

	// Unsubscribe method is used to stop observing resource.
	Unsubscribe(ctx context.Context, key, chanID, subptopic, token string) error
}

Service specifies CoAP service API.

func New

func New(authClient magistrala.AuthzServiceClient, pubsub messaging.PubSub) Service

New instantiates the CoAP adapter implementation.