### Start Database Pool in OTP Supervisor

Source: https://github.com/lpil/pog/blob/main/README.md

Configure and start a Pog database connection pool as a child process in an OTP supervision tree. Ensure the pool is started before any processes that will use it.

```gleam
import gleam/otp/static_supervisor as supervisor
import gleam/erlang/process
import pog

pub fn start_application_supervisor(pool_name: process.Name(pog.Message)) {
  let pool_child = 
    pog.default_config(pool_name)
    |> pog.host("localhost")
    |> pog.database("my_database")
    |> pog.pool_size(15)
    |> pog.supervised

  supervisor.new(supervisor.RestForOne)
  |> supervisor.add(pool_child)
  // |> supervisor.add(other)
  // |> supervisor.add(application)
  // |> supervisor.add(children)
  |> supervisor.start
}
```

--------------------------------

### Dockerfile for Adding CA Certificates

Source: https://github.com/lpil/pog/blob/main/docs/solving-ssl-issues.md

This Dockerfile example demonstrates how to update package managers, install CA certificates, and add custom certificates (like AWS RDS certificates) to the system's trusted certificate store. This is useful for Alpine-based images or when dealing with self-signed CAs.

```dockerfile
# Update your package manager.
RUN apt update
# Add the main CA certificates.
RUN apt install -y ca-certificates inotify-tools curl
# Get the latest CA certificates.
RUN update-ca-certificates
# Get the certificate form AWS.
RUN mkdir -p /aws-certificates
RUN curl -o /aws-certificates/rds.pem https://truststore.pki.rds.amazonaws.com/global/global-bundle.pem
# Provide the CA certificate in the OS directly.
RUN cat /aws-certificates/rds.pem >> /etc/ssl/certs/ca-certificates.crt
```

--------------------------------

### Execute a Query with Parameters and Decode Results

Source: https://github.com/lpil/pog/blob/main/README.md

Execute a SQL query with parameters and decode the returned rows into a specific Gleam structure. This example demonstrates fetching cat data by ID and asserting the results.

```gleam
import pog
import gleam/dynamic/decode

pub fn run(db: pog.Connection) {
  // An SQL statement to run. It takes one int as a parameter
  let sql_query = "
  select
    name, age, colour, friends
  from
    cats
  where
    id = $1"

  // This is the decoder for the value returned by the query
  let row_decoder = {
    use name <- decode.field(0, decode.string)
    use age <- decode.field(1, decode.int)
    use colour <- decode.field(2, decode.string)
    use friends <- decode.field(3, decode.list(decode.string))
    decode.success(#(name, age, colour, friends))
  }

  // Run the query against the PostgreSQL database
  // The int `1` is given as a parameter
  let assert Ok(data) = 
    pog.query(sql_query)
    |> pog.parameter(pog.int(1))
    |> pog.returning(row_decoder)
    |> pog.execute(db)

  // And then do something with the returned results
  assert data.count == 2
  assert data.rows == [#("Nubi", 3, "black", ["Al", "Cutlass"])]
}
```

--------------------------------

### PEM Certificate Structure Example

Source: https://github.com/lpil/pog/blob/main/docs/solving-ssl-issues.md

This is an example of the structure of a PEM certificate, commonly used for SSL/TLS communication. It includes the BEGIN and END markers and the base64 encoded certificate data.

```text
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
```

--------------------------------

### Set Postgres Environment Variables

Source: https://github.com/lpil/pog/blob/main/test/README.md

Configure these environment variables before running tests to connect to the Postgres database.

```sh
export PGUSER="postgres"
export PGHOST="localhost"
export PGPASSWORD="postgres"
export PGUSER="postgres"
export PGPORT=5432
```

--------------------------------

### Read Connection URI from Environment

Source: https://github.com/lpil/pog/blob/main/README.md

Configure a Pog database connection using a connection URI string read from the DATABASE_URL environment variable. This function returns a Result, handling potential errors during environment variable retrieval or URI parsing.

```gleam
import envoy
import gleam/erlang/process.{type Name}
import pog

/// Read the DATABASE_URL environment variable and then
/// build the pog.Config from that database URL.
pub fn read_connection_uri(name: Name(pog.Message)) -> Result(pog.Config, Nil) {
  use database_url <- result.try(envoy.get("DATABASE_URL"))
  pog.url_config(name, database_url)
}
```

--------------------------------

### Add Pog Dependency

Source: https://github.com/lpil/pog/blob/main/README.md

Add the Pog package to your Gleam project using the Gleam package manager.

```gleam
gleam add pog@4
```

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