What

I've ran into an issue where I thought Vite and NextJS weren't exporting files correctly. The browser was throwing exceptions when loading javascript resources.

After lots of debugging, I figured that the site only breaks whilst I was running it in the static -webserver. That got my suspicion going with the environment variable replacement.

Diagnosis

This container replaces all variables with the following pattern: ${MY_ENVIRONMENT_VARIABLE}. So I started searching for ${ in my static exported javascript files. It might not be a surprise anymore that modern javascript can use variables in backtick strings:

const string = `a string with a ${variable}`;

In recent exports, backtick strings became supported in all browsers, and this this is now valid browser compatible javascript.

Another finding was that empty variables also got replaced. So ${} was just replaced with nothing.

Desired solution

We might want to release a new version with different environment variable replacement. Options are:

• Only replace environment variables with a specific prefix, and put those as a filter in the envsubst command
• Find a different replacement method, and use ![[MY_ENVIRONMENT_VARIABLE]] or something like that
• Add a variable that lists all the environment variables that should be replaced (whitelist)

My workaround

How I solved it now in my personal project, was by overwriting 40-envsubst-on-www.sh in the dockerfile, putting:

# Only replace variables in .html, .xml and .txt files
find "$www_dir" -regex '.*\.\(html\|xml\|txt\)$' -type f -exec sh -c 'envsubst < $0 > $0.tmp && mv $0.tmp $0' {} \;

Currently the default behaviour is to try the files directly or load an index.html

It would be nice to implement support for a 404 file / template since apache and nginx support this:

ErrorDocument 404 /new404.html

https://nginx.org/en/docs/http/ngx_http_core_module.html#error_page

serve responsibly.

i needed to overwrite some configuration in the vhost but in the current setup this requires a complete overwrite of nginx.conf

• permission denied error when copying files as nginx to /var/www
• every file is copied on startup. should only be files that match an environment variable

The file / folder is created by default and should be removed