sbt 1.5.0 added aThisBuild / packageTimestamp setting to fix Play's last-modified header. The problem is, it doesn't work. SettingThisBuild / packageTimestamp has no effect on Play's packaged assets.

This PR fixes the settings to respectThisBuild / packageTimestamp for Play assets. Additionally, there is anAssets / packageTimestamp setting which can set asset timestamps differently from other packaging.

For example, this configuration is valid:

// use the git HEAD commit timestamp as the last-modified header for assetsAssets/ packageTimestamp:=Package.gitCommitDateTimestamp// use 2010 timestamp for other packaging (e.g. class files in jars)ThisBuild/ packageTimestamp:=Package.fixed2010Timestamp

I updated the docs to recommend settingpackageTimestamp instead ofpackageOptions.

Fixes#10572

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dwickern added2 commits

February 23, 2025 13:37

respect packageTimestamp option for assets

c9e1e8f

update docs

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dwickern commentedFeb 24, 2025•
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It's possible that

Assets/ packageTimestamp:=Package.keepTimestamps

would be a reasonable default.

Personally I would have to revert it back because I useSOURCE_DATE_EPOCH. But I could see changing it for the benefit of users who just leave things at their default.

Edit: actually, this default would be the best of both worlds

Assets/ packageTimestamp:=  sys.env.get("SOURCE_DATE_EPOCH")    .map(_.toLong*1000)    .orElse(Package.keepTimestamps)

dwickern marked this pull request as draft

February 24, 2025 04:24

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mkurz commentedFeb 24, 2025

Edit: actually, this default would be the best of both worlds

Yeah, I think this is the best solution. This basically restores sbt 1.4.0 behaviour (for Assets, at least), while also takesSOURCE_DATE_EPOCH into account.