# HTTP adapter

HTTP adapter provides an HTTP 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               |
| --------------------------- | --------------------------------------------------- | --------------------- |
| MF_HTTP_ADAPTER_LOG_LEVEL   | Log level for the HTTP Adapter                      | error                 |
| MF_HTTP_ADAPTER_PORT        | Service HTTP port                                   | 8180                  |
| MF_NATS_URL                 | NATS instance URL                                   | nats://localhost:4222 |
| MF_HTTP_ADAPTER_CLIENT_TLS  | Flag that indicates if TLS should be turned on      | false                 |
| MF_HTTP_ADAPTER_CA_CERTS    | Path to trusted CAs in PEM format                   |                       |
| MF_JAEGER_URL               | Jaeger server URL                                   | localhost:6831        |
| MF_THINGS_AUTH_GRPC_URL     | Things service Auth gRPC URL                        | localhost:8181        |
| MF_THINGS_AUTH_GRPC_TIMEOUT | Things service Auth gRPC request timeout in seconds | 1s                    |

## Deployment

The service itself is distributed as Docker container. Check the [`http-adapter`](https://github.com/mainflux/mainflux/blob/master/docker/docker-compose.yml#L245-L262) service section in 
docker-compose to see how service is deployed.

To start the service outside of the container, execute the following shell script:

```bash
# download the latest version of the service
git clone https://github.com/mainflux/mainflux

cd mainflux

# compile the http
make http

# copy binary to bin
make install

# set the environment variables and run the service
MF_NATS_URL=[NATS instance URL] \
MF_HTTP_ADAPTER_LOG_LEVEL=[HTTP Adapter Log Level] \
MF_HTTP_ADAPTER_PORT=[Service HTTP port] \
MF_HTTP_ADAPTER_CA_CERTS=[Path to trusted CAs in PEM format] \
MF_JAEGER_URL=[Jaeger server URL] \
MF_THINGS_AUTH_GRPC_URL=[Things service Auth gRPC URL] \
MF_THINGS_AUTH_GRPC_TIMEOUT=[Things service Auth gRPC request timeout in seconds] \
$GOBIN/mainflux-http
```

Setting `MF_HTTP_ADAPTER_CA_CERTS` expects a file in PEM format of trusted CAs. This will enable TLS against the Things gRPC endpoint trusting only those CAs that are provided.

## Usage

HTTP Authorization request header contains the credentials to authenticate a Thing. The authorization header can be a plain Thing key
or a Thing key encoded as a password for Basic Authentication. In case the Basic Authentication schema is used, the username is ignored.
For more information about service capabilities and its usage, please check out
the [API documentation](https://api.mainflux.io/?urls.primaryName=http.yml).

[doc]: https://docs.mainflux.io