Mainflux.mainflux/readers/postgres/README.md

# Postgres reader

Postgres reader provides message repository implementation for Postgres.

## 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_POSTGRES_READER_LOG_LEVEL        | Service log level                             | info           |
| MF_POSTGRES_READER_PORT             | Service HTTP port                             | 9009           |
| MF_POSTGRES_READER_CLIENT_TLS       | TLS mode flag                                 | false          |
| MF_POSTGRES_READER_CA_CERTS         | Path to trusted CAs in PEM format             |                |
| MF_POSTGRES_READER_DB_HOST          | Postgres DB host                              | postgres       |
| MF_POSTGRES_READER_DB_PORT          | Postgres DB port                              | 5432           |
| MF_POSTGRES_READER_DB_USER          | Postgres user                                 | mainflux       |
| MF_POSTGRES_READER_DB_PASS          | Postgres password                             | mainflux       |
| MF_POSTGRES_READER_DB               | Postgres database name                        | messages       |
| MF_POSTGRES_READER_DB_SSL_MODE      | Postgres SSL mode                             | disabled       |
| MF_POSTGRES_READER_DB_SSL_CERT      | Postgres SSL certificate path                 | ""             |
| MF_POSTGRES_READER_DB_SSL_KEY       | Postgres SSL key                              | ""             |
| MF_POSTGRES_READER_DB_SSL_ROOT_CERT | Postgres SSL root certificate path            | ""             |
| MF_JAEGER_URL                       | Jaeger server URL                             | localhost:6831 |
| MF_THINGS_AUTH_GRPC_URL             | Things service Auth gRPC URL                  | localhost:7000 |
| MF_THINGS_AUTH_GRPC_TIMEOUT         | Things service Auth gRPC timeout in seconds   | 1s             |
| MF_AUTH_GRPC_URL                    | Users service gRPC URL                        | localhost:7001 |
| MF_AUTH_GRPC_TIMEOUT                | Users service gRPC request timeout in seconds | 1s             |
| MF_SEND_TELEMETRY                   | Send telemetry to mainflux call home server   | true           |

## Deployment

The service itself is distributed as Docker container. Check the [`postgres-reader`](https://github.com/mainflux/mainflux/blob/master/docker/addons/postgres-reader/docker-compose.yml#L17-L41) service section in 
docker-compose to see how service is deployed.

To start the service, execute the following shell script:

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

cd mainflux

# compile the postgres writer
make postgres-writer

# copy binary to bin
make install

# Set the environment variables and run the service
MF_POSTGRES_READER_LOG_LEVEL=[Service log level] \
MF_POSTGRES_READER_PORT=[Service HTTP port] \
MF_POSTGRES_READER_CLIENT_TLS =[TLS mode flag] \
MF_POSTGRES_READER_CA_CERTS=[Path to trusted CAs in PEM format] \
MF_POSTGRES_READER_DB_HOST=[Postgres host] \
MF_POSTGRES_READER_DB_PORT=[Postgres port] \
MF_POSTGRES_READER_DB_USER=[Postgres user] \
MF_POSTGRES_READER_DB_PASS=[Postgres password] \
MF_POSTGRES_READER_DB=[Postgres database name] \
MF_POSTGRES_READER_DB_SSL_MODE=[Postgres SSL mode] \
MF_POSTGRES_READER_DB_SSL_CERT=[Postgres SSL cert] \
MF_POSTGRES_READER_DB_SSL_KEY=[Postgres SSL key] \
MF_POSTGRES_READER_DB_SSL_ROOT_CERT=[Postgres SSL Root cert] \
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-postgres-reader
```

## Usage

Starting service will start consuming normalized messages in SenML format.

Comparator Usage Guide:
| Comparator           | Usage                                                                       |      Example                       |  
|----------------------|-----------------------------------------------------------------------------|------------------------------------|
| eq                   | Return values that are equal to the query                                   | eq["active"] -> "active"           |  
| ge                   | Return values that are substrings of the query                              | ge["tiv"] -> "active" and "tiv"    |  
| gt                   | Return values that are substrings of the query and not equal to the query   | gt["tiv"] -> "active"              |  
| le                   | Return values that are superstrings of the query                            | le["active"] -> "tiv"              |  
| lt                   | Return values that are superstrings of the query and not equal to the query | lt["active"] -> "active" and "tiv" |  

Official docs can be found [here](https://docs.mainflux.io).