docker-pdns/pdns-recursor/docker-entrypoint.sh

#!/bin/sh

set -eu

#### Function definitions
function deriveConfigValuesFromEnvrionement {
  # Configure base vars
  : "${PDNS_local_port:=53}"
  : "${PDNS_local_address:=0.0.0.0}"
  : "${PDNS_allow_from:=0.0.0.0/0}"
  
  export PDNS_local_port PDNS_local_address PDNS_allow_from
}

### end of function definitions

if [ -f /etc/fedora-release ]; then
  config_file=/etc/pdns-recursor/recursor.conf
  pdns_user=pdns-recursor
elif [ -f /etc/alpine-release ]; then
  config_file=/etc/pdns/recursor.conf
  pdns_user=recursor
fi

if [ ${USE_EXISTING_CONFIG_FILE:-false} = 'false' ]; then 
    deriveConfigValuesFromEnvrionement
    echo "generating config file from environment"
    subvars --prefix 'PDNS_' < '/recursor.conf.tpl' > "${config_file}"
    chown "${pdns_user}:" "${config_file}"
  else
    echo "using existing config file ${config_file}"
fi    

# Create config file from template

# Fix config file ownership


exec "$@"