[MacPorts] #54800: Cache built dependency packages on Travis CI to speed up testing flow

[MacPorts]

#54800: Cache built dependency packages on Travis CI to speed up testing flow
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  Reporter:  yan12125        |      Owner:  admin@…
      Type:  enhancement     |     Status:  new
  Priority:  Normal          |  Milestone:
 Component:  server/hosting  |    Version:
Resolution:                  |   Keywords:
      Port:                  |
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Comment (by ryandesign):

 Does this look like a reasonable list of steps to accomplish this?

 * On the buildbot server, set up a new directory outside of the rsync
 directory to store nondistributable archives.
 * Change mpbb so that it uploads nondistributable archives to there. (We
 don't need to worry about cleaning up old nondistributable archives; the
 existing [ticket:56181 cleanup script] can probably be used for that.)
 * At NameCheap, make 2 new hostnames on macports.org for this: one for the
 origin (on the buildbot server) and one for the CDN.
 * On the buildbot server, configure nginx to serve the new directory via
 that new origin hostname (and also a local-network-only hostname for use
 by the buildbot), and to allow access only from MaxCDN IP addresses (and
 localhost).
 * At MaxCDN, add a new zone for this with the new CDN hostname and
 configure the zone to allow access only from Travis IPs.
 * Modify Travis config to also find packages at the new CDN hostname by
 adding an entry to archive_sites.conf.
 * Modify buildbot config to also find packages at the new local-network-
 only hostname by adding an entry to archive_sites.conf.
 * Maybe the preceding 2 happen in mpbb; if so, do we have a way in mpbb to
 differentiate whether we're running on Travis or buildbot?

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Ticket URL: <https://trac.macports.org/ticket/54800#comment:8>
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