Hi Giorgio, sajolida and others, context: we're redesigning how we're handling the pool of HTTP mirrors used to download Tails ISO images. If you want details, see the "Big picture" section on https://tails.boum.org/blueprint/HTTP_mirror_pool/
We need to add a feature to DAVE to support our new design. I'd like to check with Giorgio how possible/difficult it will be, in your opinion. And I'd like sajolida to sanity-check the plan, in particular checking compatibility with the IA. Anyone else in the audience is much welcome to help, of course :) I'll first explain what we need DAVE to do, and then I have a couple of questions, mainly for Giorgio. What we need DAVE to do ======================= We need DAVE to retrieve a JSON configuration file from our website, that describes our pool of HTTP mirrors. The exact content and format of the config file is not clear yet, but let's assume for now that it'll be a list of mirrors, with information attached to each of them: a base URL, and a weight (0 = disabled, and the bigger the number, the higher the chances to pick it). And then, whenever DAVE wants to use the ISO URL it found in the ISO description file (IDF in the new installation process specification, i.e. what is called a "descriptor" in the DAVE code base), for example to start a download, we need DAVE to pick one mirrors from this list (honoring the weight but that's the trivial part I bet), and replace the "http://dl.amnesia.boum.org/tails/"; part of the URL found in the IDF with the base URL corresponding to the mirror it picked. I bet it'll be simpler to modify a little bit the IDF format, to avoid hard-coding this part of the URL in the IDF, and write: path: /tails/stable/tails-i386-2.0/tails-i386-2.0.iso instead of the current: url: http://dl.amnesia.boum.org/tails/stable/tails-i386-2.0/tails-i386-2.0.iso ... but this is a detail at this stage, and I think we can ensure a smooth migration path without having to bump the IDF format to v2. Questions ========= I assume that doing most of this (retrieving and loading the JSON config file, picking an element from a list, doing simple string/URL mangling) in DAVE is pretty basic stuff, that anyone moderately experienced in JavaScript could do, without expertise that's specific to Firefox add-on development. Correct? What I'm more concerned about is the integration of the basic pieces into the clever stuff that DAVE does. E.g. I see that it is maintaining a state machine (status.phase), that is used to retry/continue downloads, display progress, trigger verification etc., so for example we need to be careful when exactly we pick a mirror and build the ISO URL (we have to do it before the download starts, but shall we re-do it every time we retry?). This is just an example of the class of issues I expect we will have to solve when implementing what we need. How hard does it sound? Any other problems you would expect us to face? Will you be happy to review our DAVE patch, once we have something that Works For Me™? Likely we will be working on it on April 6-8, and ideally we would need the new feature to be on AMO by the end of April. Also, it would be awesome if we could ask you one or three questions when we hit technical difficulties along the way, but if you can't do it, it's fine, I guess we can ask for help to other add-on developers we know :) To end with, can you please give a quick look at our existing JS code, and tell us if anything can't possibly work in a Firefox add-on such as DAVE, or really, if anything raises a red light: https://git-tails.immerda.ch/mirror-pool-dispatcher/ This draft code implements something very similar to what I'm describing here, except it's meant to be loaded and run from a web page that has a download link, instead of from a Firefox extension (which I think we will need for downloads that are not mediated by DAVE). Cheers, -- intrigeri _______________________________________________ Tails-dev mailing list [email protected] https://mailman.boum.org/listinfo/tails-dev To unsubscribe from this list, send an empty email to [email protected].
