So Juju would certainly let you run an older binary, and it would, indeed, switch to that binary. What it has *never* done is back out any actual changes to your environment. So any upgrade that changed any data on disk (the contents of agent.conf, a cert, something like that) would remain in the upgraded content. And explicitly 1.16 => 1.18 changed agent.conf in a way that old agents would fail to read the new agent.conf file. And we had a bug where upgrading from 1.16 => 1.18 would succeed, but then immediately try to revert back to 1.16 (because 1.18 prefers to upgrade in an ordered fashion, with machines upgrading before units, so if the unit upgraded first, it would try to downgrade back before proceeding.)
I would be ok with allowing downgrades within a PATCH level, but I think it still holds true that downgrades are very untested, and downgrading across a MINOR version is almost definitely always going to do something bad. That said, I think for CI getting bootstrap to target an explicit version is far better than bootstrapping to the latest trunk, and then downgrading. I would be willing to compromise in the short term by adjusting the "refuse to downgrade" to only refuse to change Major.Minor versions. It still fixes the existing bug, and would let CI continue. John =:-> On Thu, Apr 10, 2014 at 6:45 PM, Aaron Bentley <[email protected]>wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 14-04-10 05:41 AM, John Meinel wrote: > > Well you used to be able to request a downgrade, but it never > > actually worked... :)o > > Could you explain that further? > > We've done thousands of downgrades and juju reported that it had > switched the agent to the requested version. > > We first implemented downgrading in November or so. Are you saying > Juju has been lying the whole time? > > Aaron > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQEcBAEBAgAGBQJTRq6MAAoJEK84cMOcf+9hnkAH/iMBtxxJJkacqq2oM25EA6iv > FbkCClUGBOJweEHVqgWugVNacS/gX9CQjDyOfPF2MVlB7VTxIuw55ysxLn/DyAJI > TVOOi08rEl0G6wUVguMcwrOyuyK35X2CX+BwN/XNDw1deKEN8Qy0c/wfdVPq0pvi > 90c09VgS/7VEKb0fC9JYT6vlaB/2u+uHDQQflpdpCQOD2jCFk/KbLUjudN6ivq5n > e69/8k4gUKbJTnEO2DH8X+oKX9/O3yZwXUKcYmz9FpDveTGoaBIqwZjsVxdx7HzS > O80zVVi/opw4qLjwOmpb1mXTSKqL9c61Fdj4+04TQrG5PM9nkNrfTJWrkzk2prk= > =Z3my > -----END PGP SIGNATURE----- > > -- > Juju-dev mailing list > [email protected] > Modify settings or unsubscribe at: > https://lists.ubuntu.com/mailman/listinfo/juju-dev >
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