Set an environment variable without restarting the container

[MurzNN]

Is there any way to set or change an env (environment variable) value without the full restart of the web container?

I know that I can temporarily set it for the current terminal, but need to set it for other processes (including the php-fpm) too.

And it's ok that it will be dropped or reset after the restart.

[MurzNN]

I've invented a workaround to set the ENV variable to the php-fpm process and current term via a simple one-liner:

printf "\nenv[BOTVA] = botven\n" >> /etc/php/$DDEV_PHP_VERSION/fpm/pool.d/www.conf; supervisorctl restart php-fpm

Maybe it's a good idea to move this to a utility script inside ddev? Do we have them already?

[MurzNN]

And here is a more detailed script, that applies the ENV value to the new terminals, and also to the current (if ran with source prefix):
cat /usr/local/bin/ddev-setenv:

#!/bin/bash

if [[ "$1" == *"="* ]]; then
  ENV=$(echo "$1" | cut -d '=' -f 1)
  VALUE=$(echo "$1" | cut -d '=' -f 2)
else
  ENV=$1
  VALUE=$2
fi

FILE_TERMINAL1=~/.profile
FILE_TERMINAL2=~/.bashrc
FILE_FPM=/etc/php/$DDEV_PHP_VERSION/fpm/pool.d/www.conf

# If arguments are empty.
if [ -z "$ENV" ]; then
  echo "Usage format:
$0 ENV value
or
$0 ENV=value
"
  exit
fi

# Removing the line if the value is empty, because php-fpm doesn't support empty values.
if [ -z "$VALUE" ]; then
  sed -i "s/^env\[$ENV\] = .*//" $FILE_FPM
else
  sed -i "/^env\[$ENV\] = /{h;s/ = .*/ = $VALUE/};\${x;/^$/{s//env\[$ENV\] = $VALUE/;H};x}" $FILE_FPM
fi

sed -i "/^export $ENV=/{h;s/=.*/=$VALUE/};\${x;/^$/{s//export $ENV=$VALUE/;H};x}" $FILE_TERMINAL1
sed -i "/^export $ENV=/{h;s/=.*/=$VALUE/};\${x;/^$/{s//export $ENV=$VALUE/;H};x}" $FILE_TERMINAL2

supervisorctl restart php-fpm

# This will not work if ran as a subshell
# The solution is to run the script with `source` prefix
# source /usr/local/bin/setenv NAME VALUE
export $ENV="$VALUE"
if [ "$0" = "$BASH_SOURCE" ]; then
  echo "Warning: To apply the ENV variable also to the current terminal, execute it via this command:"
  echo "source $0 $1 $2"
fi

echo "Environment variable successfully set: $ENV=\"$VALUE\""

Usage example:

$ source ddev-setenv MY_COOL_VARIABLE "My cool value"
php-fpm: stopped
php-fpm: started
Environment variable successfully set: MY_COOL_VARIABLE=My cool value

Can we include it into DDEV web container?

[MurzNN]

To get your script into the container, just add it to your project and use it there. For example, put it in the project's bin directory, which is automatically added to $PATH.

Yes, I know how to mount it manually, but I'm asking about including it (or something similar) into the DDEV package, because I think it's a pretty common task to change an ENV variable value quickly, without a full slow restart of the container. What do you think about it?

For me, this script is very useful to test feature flags in the app, so via a couple of seconds I can switch it on and off, and test the behavior of the app.

And not all apps read use .env file to read values, most of them just take it from the environment directly, so writing to .env file is not a solution.

[rfay]

You're the first to ask this in all these years, probably because most apps don't depend on env variables being defined in php-fpm, they use their own techniques to get the environment. What CMS or framework are you working with ? Maybe if I understand more clearly the problem you're trying to solve I can be more helpful.

[MurzNN]

I'm working with Drupal, but "feature flags" is a common practice for many projects. So, when you're developing and releasing a new feature to production, you put a dependency on an env variable, eg ENABLE_ROUTING_V2=1 to enable it, so if the brand new feature works not such good as expected, you can quickly disable it, and revert the previous behavior via ENABLE_ROUTING_V2=0.

So to test this locally - developers need a way to quickly change the ENV variable value, without waiting for full restart of the container.

And my script is already delivered to our team, and all are happy with it :)

[rfay]

So if you were using the dotenv module for vars like this you could just change the .env and it would take immediate effect, right? Also note that you can accomplish the same thing by just changing a settings.local.php file, which would be the most common Drupal way to handle things like this.

[MurzNN]

Yes, using the dotenv is a workaround, but it is a redundant dependency for projects that work in containers, because it does an additional check of the file on each query. But settings.local.php is a good workaround, thanks for the tip! But this script should work for all scripts, not only for Drupal.