Possible improvement on Docker support

[lextm]

Currently the steps documented for Docker support do not quite match real world setup,

• It's not quite common to use a Node image for production deployment.
• yarn start clearly is using the debug build.

To support a commonly used base image such as nginx, which does not have Node installed, the challenge is how to generate __ENV.js on the fly without Node.

I attached a shell script below that works in a similar way,

#!/bin/sh

# react-env.sh

scriptname="./__ENV.js"
sourcename="$1"

if [ -z "$sourcename" ]; then
  current=$(eval "echo \"\$ENVIRONMENT\"")
  if [ -z "$current" ]; then
    sourcename=".env"
  else
    sourcename=".env.$current"
  fi
fi

# Recreate config file
rm -rf "$scriptname"
touch "$scriptname"

# Add assignment 
echo "window.__ENV = {" >> "$scriptname"

# Read each line in .env file
# Each line represents key=value pairs
while read -r line || [ -n "$line" ];
do
  if printf '%s\n' "$line" | grep -q -e '^#.*'; then
    continue
  fi

  [ -z "$line" ] && continue

  # Split env variables by character `=`
  if printf '%s\n' "$line" | grep -q -e '='; then
    varname=$(printf '%s\n' "$line" | sed -e 's/=.*//')
    varvalue=$(printf '%s\n' "$line" | sed -e 's/^[^=]*=//')
  fi

  # Read value of current variable if exists as Environment variable
  env=$(eval "echo \"\$$varname\"")
  value=$(printf '%s\n' "$env")
  # Otherwise use value from .env file
  [ -z "$value" ] && value=${varvalue}
  
  # Append configuration property to JS file
  echo "  $varname: \"$value\"," >> "$scriptname"
done < "$sourcename"

echo "}" >> "$scriptname"

It is written in POSIX sh syntax, as many base images don't have bash.

[christian-draeger]

would be really nice to see this as a build in feature of react-env