# Postgres writer

Postgres writer 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_NATS_URL                         | NATS instance URL                                                       | nats://localhost:4222  |
| MF_POSTGRES_WRITER_LOG_LEVEL        | Service log level                                                       | error                  |
| MF_POSTGRES_WRITER_PORT             | Service HTTP port                                                       | 9104                   |
| MF_POSTGRES_WRITER_DB_HOST          | Postgres DB host                                                        | postgres               |
| MF_POSTGRES_WRITER_DB_PORT          | Postgres DB port                                                        | 5432                   |
| MF_POSTGRES_WRITER_DB_USER          | Postgres user                                                           | mainflux               |
| MF_POSTGRES_WRITER_DB_PASS          | Postgres password                                                       | mainflux               |
| MF_POSTGRES_WRITER_DB               | Postgres database name                                                  | messages               |
| MF_POSTGRES_WRITER_DB_SSL_MODE      | Postgres SSL mode                                                       | disabled               |
| MF_POSTGRES_WRITER_DB_SSL_CERT      | Postgres SSL certificate path                                           | ""                     |
| MF_POSTGRES_WRITER_DB_SSL_KEY       | Postgres SSL key                                                        | ""                     |
| MF_POSTGRES_WRITER_DB_SSL_ROOT_CERT | Postgres SSL root certificate path                                      | ""                     |
| MF_POSTGRES_WRITER_CONFIG_PATH      | Config file path with NATS subjects list, payload type and content-type | /config.toml           |

## Deployment

The service itself is distributed as Docker container. Check the [`postgres-writer`](https://github.com/mainflux/mainflux/blob/master/docker/addons/postgres-writer/docker-compose.yml#L34-L59) 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_NATS_URL=[NATS instance URL] \
MF_POSTGRES_WRITER_LOG_LEVEL=[Service log level] \
MF_POSTGRES_WRITER_PORT=[Service HTTP port] \
MF_POSTGRES_WRITER_DB_HOST=[Postgres host] \
MF_POSTGRES_WRITER_DB_PORT=[Postgres port] \
MF_POSTGRES_WRITER_DB_USER=[Postgres user] \
MF_POSTGRES_WRITER_DB_PASS=[Postgres password] \
MF_POSTGRES_WRITER_DB=[Postgres database name] \
MF_POSTGRES_WRITER_DB_SSL_MODE=[Postgres SSL mode] \
MF_POSTGRES_WRITER_DB_SSL_CERT=[Postgres SSL cert] \
MF_POSTGRES_WRITER_DB_SSL_KEY=[Postgres SSL key] \
MF_POSTGRES_WRITER_DB_SSL_ROOT_CERT=[Postgres SSL Root cert] \
MF_POSTGRES_WRITER_CONFIG_PATH=[Config file path with NATS subjects list, payload type and content-type] \
$GOBIN/mainflux-postgres-writer
```

## Usage

Starting service will start consuming normalized messages in SenML format.