Output CloudFront-friendly headers for diffs #1098
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This is part of web-monitoring#168 — the goal here is to make our diff cache less important so we can shrink it or even remove it (in favor of just having CloudFront do the job).
CloudFront needs a
Date
header to go with theLast-Modified
andETag
headers from thestale?
method, and works better still if we give it an actual cache age. This adds theexpires_in
helper which sets all the headers. I've also taken the strategy of setting a relatively short cache time but a much longer revalidation window when a stale response can be used, to balance concerns about updating the diff algorithm and effective long-term caching.