Hard-coding timestamp in manifest.mf for docker cache

Help/Discuss
1

Hi there,

I already have something like this to set each entry inside generated Jars to a constant timestamp:

     tasks.withType(Jar) {
        eachFile { FileCopyDetails details ->
            details.getFile().setLastModified(0L);
            def pf = details.getFile();
            while (pf != null && (pf = pf.getParentFile()) != null) {
                pf.setLastModified(0);
            }
        }
    }

however I can’t find a way to get a handle on META-INF/ and META-INF/MANIFEST.MF entries to set their modification timestamps to a constant too. Is this a bug (because eachFile doesn’t callback on manifest file) or is there some other kind of workaround that I can use?

Use case: the jars are eventually added to a docker image. Because of the timestamp difference in the jar file’s manifest file, the md5 of the file changes and trips up the docker cache.

2

try using the rootSpec explicitly here:

tasks.withType(Jar) {
    rootSpec.eachFile { FileCopyDetails details ->
        details.getFile().setLastModified(0L);
        def pf = details.getFile();
        while (pf != null && (pf = pf.getParentFile()) != null) {
            pf.setLastModified(0);
        }
    }
}
3

Thank you, that gives me build/tmp/MANIFEST.MF but unfortunately the resultant entry that gets written to the JAR file still reflects the build time instead of the constant time :frowning:

4

My current workaround that works (but inefficient):

    jar {
        duplicatesStrategy= DuplicatesStrategy.EXCLUDE
        doLast {
            long ts = 0;
            File newJar = new File(archivePath.parent, 'new-' + archiveName)
            ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(newJar))
            JarFile jf = new JarFile(archivePath)
            jf.entries().each { entry ->
                ZipEntry clone = new ZipEntry(entry)
                clone.time = 0
                def entryIs = jf.getInputStream(entry)
                zos.putNextEntry(clone)
                byte[] buffer = new byte[1024]
                int len = 0
                while((len = entryIs.read(buffer)) != -1) {
                    zos.write(buffer, 0, len)
                }
            }
            zos.finish()
            jf.close()
        }
        doLast {
            new File(archivePath.parent, 'new-' + archiveName).renameTo(new File(archivePath.parent, archiveName))
        }
    }