# 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_SUBJECTS_CONFIG  | Configuration file path with subjects list | /config/subjects.toml  |
| MF_POSTGRES_WRITER_CONTENT_TYPE     | Message payload Content Type               | application/senml+json |

## Deployment

```yaml
  version: "3.7"
  postgres-writer:
    image: mainflux/postgres-writer:[version]
    container_name: [instance name]
    depends_on:
      - postgres
      - nats
    restart: on-failure
    environment:
      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_SUBJECTS_CONFIG: [Configuration file path with subjects list]
      MF_POSTGRES_WRITER_CONTENT_TYPE: [Message payload Content Type]
    ports:
      - 9104:9104
    networks:
      - docker_mainflux-base-net
    volume:
      - ./subjects.yaml:/config/subjects.yaml
```

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_SUBJECTS_CONFIG=[Configuration file path with subjects list] \
$GOBIN/mainflux-postgres-writer
```

## Usage

Starting service will start consuming normalized messages in SenML format.
