Undefined constant in *docker-integration.php*

Problem

The php-fpm container crashes with the following in the logs since 5c3d0f0a if /app/media¹ is populated²:

Fatal error: Uncaught Error: Undefined constant "S3_DEBUG" in /app/wp-content/mu-plugins/docker-integration.php:71
Stack trace:
#0 /app/wp-includes/class-wp-hook.php(324): WP_CLI\Runner->{closure}(Array)
#1 /app/wp-includes/plugin.php(205): WP_Hook->apply_filters(Array, Array)
#2 /app/wp-content/mu-plugins/s3-uploads/inc/class-plugin.php(373): apply_filters('s3_uploads_s3_c...', Array)
#3 /app/wp-content/mu-plugins/s3-uploads/inc/class-plugin.php(334): S3_Uploads\Plugin->get_aws_sdk()
#4 /app/wp-content/mu-plugins/s3-uploads/inc/class-wp-cli-command.php(199): S3_Uploads\Plugin->s3()
#5 [internal function]: S3_Uploads\WP_CLI_Command->upload_directory(Array, Array)
#6 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php(100): call_user_func(Array, Array, Array)
#7 [internal function]: WP_CLI\Dispatcher\CommandFactory::WP_CLI\Dispatcher\{closure}(Array, Array)
#8 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/Subcommand.php(497): call_user_func(Object(Closure), Array, Array)
#9 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(441): WP_CLI\Dispatcher\Subcommand->invoke(Array, Array, Array)
#10 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(464): WP_CLI\Runner->run_command(Array, Array)
#11 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1295): WP_CLI\Runner->run_command_and_exit()
#12 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/WP_CLI/Bootstrap/LaunchRunner.php(28): WP_CLI\Runner->start()
#13 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/bootstrap.php(83): WP_CLI\Bootstrap\LaunchRunner->process(Object(WP_CLI\Bootstrap\BootstrapState))
#14 phar:///usr/local/lib/wp-cli.phar/vendor/wp-cli/wp-cli/php/wp-cli.php(32): WP_CLI\bootstrap()
#15 phar:///usr/local/lib/wp-cli.phar/php/boot-phar.php(20): include('phar:///usr/loc...')
#16 /usr/local/lib/wp-cli.phar(4): include('phar:///usr/loc...')
#17 {main}
  thrown in /app/wp-content/mu-plugins/docker-integration.php on line 71
Error: There has been a critical error on this website.Learn more about troubleshooting WordPress. There has been a critical error on this website.

Solution

The debug switches need to be set earlier in the setup steps.

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1. An additional problem to address: s3_setup needs to use the dynamic value of the uploads directory, not static /app/media. ↩

2. It seems some plugins pollute populate the upload directory even when there is no media there. ↩