Set App Hosting overrides for NextJS apps without a Next Config

[mathu97]

Currently we're skipping adding FAH overrides for Next projects that don't have a Next Config file.

[annajowang]

lgtm with some comments

[annajowang]

i'm not too sure about passing this extra userNextConfigExists, if we can avoid it. and since the value of userNextConfigExists determines which blocks of code get executed in each function, i think that means we can re-org the code a little so it's more predictable what happens in each function without having to read each line.

My initial question is do we even need to validate our own default / provided nextjs config? If not I think we could do something much more similar to the original code. Maybe:

const userNextConfigExists = await exists(join(root, originalConfig.configFileName));
if (userNextConfigExists) {
  await overrideNextConfig(root, originalConfig.configFileName);
  await validateNextConfigOverride(root, opts.projectDirectory, originalConfig.configFileName);
} else {
  // call some new function to write the DEFAULT_NEXT_CONFIG_FILE
}

Alternatively (my slight preference), we just do:

  await overrideNextConfig(root, originalConfig.configFileName);
  await validateNextConfigOverride(root, opts.projectDirectory, configFileName);

but overrideNextConfig() now handles two additional things:
(1) whether userNextConfigExists (and then writing DEFAULT_NEXT_CONFIG_FILE if not)
(2) ensuring that the preservedConfigFile still exists (instead of doing this in the validate function)

Then we don't have to pass around userNextConfigExists, validateNextConfig does not have to care if this is the original, if userconfigexists, etc.

also (2) relies on some details like knowing the original file prefix next.config.original.... So I think it would be good to keep any logic that requires knowing that prefix contained to one place.

you've thought about this more and I may be missing some challenges.

[mathu97]

My initial question is do we even need to validate our own default / provided nextjs config? If not I think we could do something much more similar to the original code. Maybe:

maybe excessive, but more importantly I don't think we need to validate the existence of the next.config.original.[js|ts|mjs] file as it is a redundant check. loadConfig will error out if for whatever reason the next.config.orignal... file doesn't exist when user's config is being overriden.

[jamesdaniels]

Does nextConfigFileName include the default filename? Then we can drop nextConfigFileName in favor.

[jamesdaniels]

Approve, nit in comment