[00:01] marcoceppi, while awesome i'd still probably recommend either cloudfront or rackfiles/limelight for a true cdn [00:01] cdn need points of presence for global effectiveness [00:02] hazmat: depends on your perspective. Sometimes all you really want is aggressive caching and fanout [00:02] latency is by far the *best* reason for CDN... but by no means the only one [00:05] mpl: Super, let me check [00:05] SpamapS, ec2 hosts don't really give fanout, all a juju node for cdn amounts to is a single host.. thats a sig difference.. it can work.. but its not the same league [00:06] mpl: Very nice [00:06] /me heads out for beer o'clock [00:06] hazmat: Cheersfully! [00:08] <_mup_> juju/go r21 committed by gustavo@niemeyer.net [00:08] <_mup_> Merged jujugo-log by branch Mathieu. [r=rog,niemeyer] [00:08] <_mup_> This branch moves logging onto the log package so that it is [00:08] <_mup_> usable by any of the subpackages, and simplifies/polishes the [00:08] <_mup_> interface further. [00:22] <_mup_> juju/scp-command r419 committed by jim.baker@canonical.com [00:22] <_mup_> Addressed review points [02:46] hazmat: It's not for a CDN, it's a patch for a CDN issue that needs to scale. So it's using hadoop charm with a custom charm I wrote that creates a sort of...CDN proxy...for an issue several customers are having because Cisco has rackcdn.com blacklisted in their enterprise router software [02:49] For those customers we have our templating engines on their site switch out rackcdn.com with another DNS and the servers fetch the file from the CDN, cache it, then serve it up. Bandaid until the blacklist is lifted which could take a while [04:35] <_mup_> juju/scp-command r420 committed by jim.baker@canonical.com [04:35] <_mup_> PEP8/PyFlakes [04:37] <_mup_> juju/scp-command r421 committed by jim.baker@canonical.com [04:37] <_mup_> Updated tab completion [04:47] <_mup_> juju/scp-command r422 committed by jim.baker@canonical.com [04:47] <_mup_> Slim down help output [04:48] <_mup_> juju/scp-command r423 committed by jim.baker@canonical.com [04:48] <_mup_> PEP8 [04:53] <_mup_> juju/trunk r425 committed by jim.baker@canonical.com [04:53] <_mup_> merge scp-command [r=fwereade,hazmat][f=720307] [04:53] <_mup_> Implements juju scp subcommand. [07:20] fwereade_: mornin' === TeTeT_ is now known as TeTeT [08:03] rog: heyhey :) [08:03] fwereade_: :-) [08:04] rog: hmm, you were up disturbingly early ;) [08:04] fwereade_: it's not uncommon - i usually don't make a peep in here until i see some activitity tho' [08:05] rog, ah, yeah, I tend to follow the same sort of approach [08:05] fwereade_: actually 7.20 *is* earlier than usual! had to go out and scrape the ice off the car. [08:05] rog, oof [08:05] not much ice where you are... :) [08:06] rog: well, it's getting pretty cold, it's 15 now :p [08:06] lol [08:06] mind you, you probably don't have working central heating... [08:07] indeed not :) [08:07] actually I just realised I need to pop out for a bit [08:07] bbs :) [08:07] c y [08:49] Mio [08:50] argh, moo, that's better [09:09] hi all [09:28] mpl: hiya [10:31] if anyone who's written trickyish charms is around and awake, please ping me [11:14] scratch my request above [11:52] Morning all! [11:52] heya niemeyer [11:52] moo [11:55] fwereade_, TheMue: Hey folks! [11:58] niemeyer, TheMue: morning! [12:03] hi rog [12:06] yo [12:13] rog, mpl: Hey folks [12:16] Sooo! Juju Charm School today. \o/ [12:20] mainerror: Ohhh, indeed! [12:20] Can't wait. [12:21] niemeyer: almost forgot about that. :P [12:21] what time (UTC) is it again? [12:23] My Charm drives me nuts. This CMS writes its config options into more than one file ... [12:23] 15:00 UTC jrgifford. [12:28] niemeyer: ec2-ec2test pushed. second stage merge request for ec2 now in (https://codereview.appspot.com/5449065/) [12:28] rog, mpl, TheMue: I think we should give a push to make sure all of the packages we're handling run fine on the latest weekly [12:28] rog: Already on re-review the former one [12:28] rog: Already on re-reviewing the former one [12:29] niemeyer: i was wondering if we should let the latest weekly settle a bit before digging in [12:30] What are you guys going to write in Go by the way? [12:30] mainerror: We're running an experiment to run juju on Go [12:30] Oh, nice. :) [12:31] Right now it is using Python, right? [12:31] mainerror: That's right [12:31] niemeyer: Based on weekly? Not on r60? [12:31] TheMue: Yeah, weekly [12:31] niemeyer: just curious? why not using the releases instead of the weeklies? [12:31] TheMue: r60 is too old by now, and given our timeframe, there's not much benefit in sticking to it [12:31] mpl: ^ [12:31] ok [12:32] niemeyer: hmm, imho weekly is currently changing too often. but i'll look. [12:32] I suspect most of the incompatibilities for Go 1 are already in too [12:33] TheMue: i think it's easier to update in stages rather than all at once. we haven't got a large set of users, so it's not that much problem for us currently. [12:33] Oh wow! Go has GTK bindings. [12:34] rog: yep, the backlog of the current weekly and the r60 is already quite large. [12:34] *sigh* [12:34] mainerror: are you speaking of mattn ones? if so, you should know that nsf is also redoing them. [12:34] Indeed. They are not 100% done yet but still a good start. [12:34] TheMue: gofix does a lot, but it's not a panacea [12:35] I see. [12:37] mpl: Did he host it on Github as well? I can't find it. :/ [12:38] mainerror: well, you'd better ask him directly on #go-nuts [12:39] Oh, awesome. :) [12:40] rog: i know, that's what i wrote on G+ too. i would like a r61 before go 1. [12:40] rog: What's the branch name? [12:41] niemeyer: which branch? [12:41] rog: The one you mentioned [12:41] niemeyer: i pointed to the codereview page. [12:41] niemeyer: it's lp:~rogpeppe/juju/go-juju-ec2-regions [12:41] rog: Ok, I feel like I'm missing something [12:41] i think [12:41] the first one is go-juju-initial-ec2 [12:41] rog: It says " juju/ec2: add code to accept an ec2 region in the configuration file" [12:42] rog: But there's a _lot_ in there, completely unrelated to this description [12:42] rog: Is there a pre-req missing? [12:42] niemeyer: yes - i couldn't add it after i'd forgotten to add it first [12:42] niemeyer: i thought you knew about the first one [12:42] rog: The first one was initial-foo, right? [12:43] rog: which we debated a lot on [12:43] rog: I haven't heard on it since? [12:43] niemeyer: https://codereview.appspot.com/5432056/ [12:43] niemeyer: i pushed a new version which is skeleton only [12:43] niemeyer: didn't you get the email? [12:43] rog: Ok, the last comment says "I'm doing that right now." [12:43] rog: Check the review out [12:44] niemeyer: ah, i did another lbox propose and changed the description, and thought you'd see that [12:44] niemeyer: anyway, there it is. [12:44] rog: Understood, thanks. I'll hack a bit on lbox today I think, to implement submit, and also to fix that problem [12:44] rog: It should mail asking for another look [12:45] niemeyer: i think there should be a distinction between uploading, mailing and changing the description [12:45] rog: But let me review your branches first.. [12:45] niemeyer: that would be good, thanks [12:45] mpl: How's your agenda? Do you have something in mind already to work on? [12:46] niemeyer: nope. I haven't really had time to think about it. I'm very open to suggestions for now ;) [12:47] mpl: May I suggest you go over all of the packages for juju, goamz, gozk, and goyaml, and see if there are any incompatibilities with weekly to be fixed? [12:47] mpl: goamz has a bunch of sub-packages as well [12:47] rog: Have you merged the error fixes on goamz that you had pending, or is there some to go still? [12:48] niemeyer: i *think* so. i'll just check [12:49] niemeyer: alright, will do. can't start on it right away though. [12:49] mpl: That's fine, thanks [12:49] mpl: After that, let's see if we come up with a more interesting/long task involving juju logic [12:50] mpl: These branches that rog is working on are the base, so it's a bit hard to split the workload, but with those in, it should be much easier [12:50] niemeyer: I'd like that. if it can involve me learning about cloud stuff, even better. [12:50] mpl: Absolutely [12:50] mpl: EC2 provider is precisely what we're working on [12:51] niemeyer: no worries. I surely don't want to disturb your workflow guys. [12:51] mpl: You're helping, rather than disturbing [12:52] psh, I know you guys have spent more time hand holding me so far than if you have done it yourself. but I'm too ashamed as it's often a necessary process. [12:52] *not too ashamed. [12:53] niemeyer: have you renamed goamz/aws yet? [12:53] anyways, gotta run to a meeting, ttyl. [12:53] niemeyer: that's the last of error-fixes in goamz [12:53] mpl: see ysa [12:53] ya [12:53] rog: Not sure.. checking [12:53] niemeyer: it still needs pushing [12:53] mpl: Cheers! [12:54] rog: Dude.. we're doing something wrong [12:54] niemeyer: we should probably tag r60 versions of the goamz packages so that people can still use r60 with them [12:54] Crap [12:54] ? [12:54] rog: Yeah, precisely [12:55] niemeyer: that's not too hard, right? [12:55] rog: That's exactly what I was talking about [12:55] rog: It's trivial [12:55] rog: But we may have broken people trying to use it [12:55] * niemeyer handles that right away [12:55] rog: Have you pushed the branch? [12:55] niemeyer: which branch? [12:55] rog: goamz/aws [12:55] niemeyer: i've pushed ec2 and s3 [12:55] niemeyer: nope [12:56] niemeyer: i don't think i sent it for review, in fact [12:56] rog: Ok, do you have any pending changes? [12:56] niemeyer: yes, just error fixes [12:56] rog: Ok, leave that with me then [12:56] rog: I'll fix the whole thing [12:57] niemeyer: there are two ErrorMatches that gofix doesn't catch, otherwise it's all gofix [12:57] rog: Cool.. I'll fix that and fix the tagging [13:00] anyone have experiences with go weekly and release in parallel? [13:00] i would need both [13:00] TheMue: i have them in separate directories [13:00] TheMue: and a prefix command to run one in preference [13:01] TheMue: http://paste.ubuntu.com/757007/ [13:01] (excuse the fact it's not bash, but i'm sure you get the idea) [13:02] TheMue: i call it "go-release". as in: go-release goinstall foo; go-release 6g x.go [13:02] etc [13:02] ic, looks good [13:06] niemeyer: gocheck looks like it needs an r60 tag too - it looks like the r59 version fails [13:06] on r60 [13:07] rog: Uh oh [13:07] rog: Can you pin-point which version to tag? [13:07] niemeyer: will do [13:07] rog: Thank you [13:11] niemeyer: ironically, it's revision 60 [13:11] rog: LOL [13:32] just off for lunch and to bake a cake, back in an hour [13:34] rog: Enjoy [13:35] ... and dcc us some cake [13:35] :) [13:43] rog: I _think_ it's all sorted out [13:43] rog: In goamz, specifically [14:17] niemeyer: cool. [14:18] TheMue: and sorry, would've but didn't have enough bananas so the cake is only 62% the size it should've been. so none spare! [14:20] rog: *deeplySigh* so I've got to find surrogate when I'm on x-mas market later with my family [14:25] jimbaker: you know what would be really cool - if you could use scp to copy between units without involving the local machine, e.g. juju scp wordpress/0:/etc/wordpress/config-* wordpress/1:/etc/wordpress [14:27] Charm school soon \o/ [14:34] * uksysadmin is ready for charm school. "How yoooou doin'?" [14:36] niemeyer: before i continue in the same vein, do you think go-juju-initial-ec2 and go-juju-ec2-region are pointing vaguely in the right direction? if not, i'd prefer to fix those rather than carry further on the wrong way. [14:38] good morning everyone! [14:38] uksysadmin: thanks for stopping by, we'll start in ~20 minutes! [14:40] niemeyer: oh cool, just got yr msg [14:49] looking forward to charming my servers [14:52] * mainerror will probably be 10 minutes late [14:53] rog: Yeah, I think initial-ec2 is ready to go in with those settled [14:53] niemeyer: [14:53] niemeyer: cool. i've done those - i'll do the push [14:54] m_3_: around? [14:56] o/ [14:56] niemeyer: done. [14:56] rog: Looking [14:57] rog: patch set is unchanged [14:57] niemeyer: is it lp:gozk or lp:~juju/gozk/zk that you want me to check? also, fyi https://launchpad.net/gozk/zk returns a 404 [14:57] rog: But it was pushed 5 minutes ago [14:58] mpl: gozk/zookeeper.. you've renamed it :-) [14:58] niemeyer: sorry, did the publish messages, did the push to ~rogpeppe..., forgot to do the lbox propose [14:58] rog: lbox propose pushes as well, btw [14:59] niemeyer: yeah but maybe you wanted me to check the whole project, wasn't sure. [14:59] niemeyer: yeah, but i've had it push to the wrong place, so i tend to do it myself to make sure [14:59] jcastro: yo [14:59] hi! [14:59] rog: Cool [15:00] mpl: Ah, no, just gozk/zookeeper is great already [15:00] niemeyer: dammit, i'm too late, the diff is empty [15:01] \m/ [15:01] niemeyer: rog: mind if we kick you out for the charm school? [15:01] jcastro: no probs [15:01] jcastro: Not at all, thanks for pushing this [15:01] but do idle in case there are questions! [15:01] Ok, welcome everyone to the first ever #juju charm school [15:01] we'll give it another minute for the stragglers to arrive [15:01] rog, mpl: => #juju-tmp [15:01] niemeyer: ah yes, silly me, your message pointing to that url (with zk) is from september. I had the rename the other way around in my head, sorry. [15:02] TheMue: => #juju-tmp [15:05] Ok everyone. [15:05] Welcome to the first ever virtual charm school!!! [15:05] I am your emcee, Jorge Castro [15:05] I work on the community team at Canonical on Cloud [15:05] I am joined today by .... [15:05] Hi all, I'm Mark Mims [15:06] I'm here to help answer charm questions [15:06] ok [15:06] so first off, we'd like to see who's here to learn, so everyone who is here for charm school, raise your hand and give us a one line description of yourself [15:06] o/ [15:06] \o [15:07] o/ I love juju [15:07] o/ [15:07] o/ (just a pm having a look) [15:07] o/ === sergio_ is now known as Guest31766 [15:07] o/ [15:08] o/ interested in learning how to deploy cloud environments in (as well as bare metal provisioning of) OpenStack [15:08] oh nice one. :) [15:08] ok so first, before we get into details on charms [15:09] let me arm you with some docs and links, that you can reference [15:09] first off, obviously, we have: https://juju.ubuntu.com/ and https://juju.ubuntu.com/docs [15:09] which is where we centralize all the information on juju [15:09] for news about juju and the latest charms, we put that on http://cloud.ubuntu.com [15:10] for example yesterday someone submitted a status.net charm [15:10] http://cloud.ubuntu.com/2011/12/deploying-status-net-quickly-with-juju/ [15:10] We like to heavily talk about new charms [15:10] because while juju is an amazing tool, it's the charms that make it useful [15:10] in the same way that you might love apt, but you really love the huge repository that comes along with it [15:11] so we're running these sessions to help people write charms for things they care about. [15:11] So, before we get into the anatomy of a charm [15:11] does anyone have any questions so far? [15:11] hopefully you understand enough about juju to grasp the concepts. [15:11] but if you don't, we can get you started on the right road. [15:11] how does one charm a package to use mysql when the current package has depends for a locally installed mysql? [15:12] erm, to use the mysql on another box.... [15:12] Do you consider juju ready for production environments? [15:12] medberry: mark is answering yours now [15:12] fmo: we consider it a tech preview in 11.10 [15:13] medberry: so the key here is to write a relation hook for your service [15:13] Thank you, it's a bit out of scope but is it the same for Orchestra? [15:13] fmo: it's at the stage where you would start to look at it for 12.04ish timeframe deployment. [15:13] medberry: that relation hook would essentially reconfigure your app to point to the remote mysql instance [15:14] nod. m_3, thanks. Is there an example charm (off the top of your head) I should refer to that does this? [15:14] medberry: it does this by exchanging crediential info for a db with the mysql charm [15:14] fmo: Not quite sure on orchestra but I /believe/ it's at the same level, though orchestra bundles some things that are already mature, like squid, etc. [15:14] m_3_: but you would still end up with unused mysql-server running on 'app' node, wouldn't it? i think this is a packaging bug [15:14] thank you :) [15:14] lots of charms connect to mysql this way... mediawiki would be a good one [15:15] fmo, I believe you can consider Orchestra more mature than Juju and ready for deployments. zul may know more. [15:15] m_3_, thanks, I'll look at it (and others) [15:15] ivoks: your relation hook could pass debconf info and dpkg-reconfig the package though [15:15] m_3_: right, thanks [15:15] ivoks: so what you would do depends on the interface exposed by the package itself [15:16] * medberry was thinking specifically of moodle if someone wants the context. [15:16] oh are you working on moodle? [15:16] that would be great! [15:16] * m_3_ grins [15:17] ok, this brings me to the next quick topic, who has written a charm already? and who is planning on working on one? [15:17] * nijaba plans on doing one for limesurvey [15:17] and does anyone have an itch to scratch to work on a certain charm? [15:17] o/ as far as getting a basic something going (like nginx behind haproxy) to try and understand the concepts [15:18] o/ postfix-dovecot [15:18] (as soon as i find time :) [15:18] (same here) [15:18] o/ finishing phpmyadmin and steam [15:19] (steam in this context is being able to quickly deploy a steam server for game clients to connect) [15:19] jcastro, yep, and someone has pointed out in O and P moodle only has a recommends on the server bits (not a depends like in Lucid.) [15:20] o/ I'm working on an alice IRC charm, which is a self hosted web irc client. [15:20] ok, so let's start with looking at the anatomy of a charm [15:20] marcoceppi, I saw that Aleph One was just released fully open source... [15:21] * marcoceppi nods [15:21] but before we start a charm [15:21] you need to map out what you want your charm to do [15:22] https://juju.ubuntu.com/docs/write-charm.html#have-a-plan [15:22] in this document we outline some tips in the things you need to think about when planning out how to write your first charm. [15:22] usually I make a quick mindmap of what I need [15:22] so for example [15:22] status.net [15:23] I know I'll need mysql [15:23] o/ - I'm a juju fanboy. [15:23] * mainerror is also late [15:23] and that the charm would have a relationship with mysql [15:23] /join #juju-tmp [15:23] http://charms.kapilt.com/interfaces/mysql [15:23] http://pad.ubuntu.com/charmschool-2011-12-02 [15:23] I can then see what other programs use mysql [15:24] this is useful because now I can look at other LAMP projects and use that to build my charm [15:24] which is what we want, reuse. [15:24] So you can use the charm browser to look for other services that have relationships with services you care about [15:24] The guy who wrote the status.net charm just derived it from his last LAMP charm [15:25] part time, it was only 2 days from first cut to being accepted into the charm school [15:25] and Marco/Clint are working on some convenience tools to make common tasks easier [15:25] marcoceppi: can you explain about your convenience functions? [15:25] (and then we'll go into this: http://pad.ubuntu.com/charmschool-2011-12-02) [15:26] wrong URL, I mean this: http://pad.ubuntu.com/charmschool-2011-12-02 [15:27] ok we can get back to Marco [15:27] Sure, so I wrote a few functions that I found myself using a lot in bash, primarily ch_get_file which is passed a file url and either a url to it's hash (md5, sha1, etc) or the actual hash itself. From there it'll download/compare file -> hash [15:27] There are a few others, check if a string is a file or a url, check if a string is a valid hash [15:28] You can find them: http://bazaar.launchpad.net/~charmers/charm-tools/trunk/view/head:/helpers/sh/net.sh to use in a charm make sure you have the juju ppa added, install charm-helper-sh, and source /usr/share/charm-helper/sh/net.sh [15:29] marcoceppi: FYI, there is a PPA just for those helpers, ppa:charmers/charm-helpers [15:29] I believe the idea is to grow out charm helpers to include helper functions in all the languages [15:29] <3 SpamapS [15:29] and if I make something I think can be reused, do we just submit it to charm tools? [15:29] marcoceppi: otherwise you'll pull in a new version of juju [15:30] SpamapS: yay! [15:30] they'll be in the distro for 12.04 [15:30] Since we're just getting a bunch of charms started, if you're writing a charm and feel that you can improve the charm tools to make it better for the next person, then we certainly encourage you to do that. [15:30] definitely [15:31] ok, any questions on the tools before m_3_ gets into the meat of a charm? [15:33] ok, moving on .... [15:33] are the tools webscale? [15:33] ;) [15:33] everyone should have this URL open: http://pad.ubuntu.com/charmschool-2011-12-02 [15:33] and we'll review this charm [15:34] Mark will bold the sections of the document he's talking about [15:34] and then when he moves on he'll unbold it and then bold the section he'll be reviewing next. [15:34] I'll give people a sec to join the pad [15:34] pad needs syntax highlighting :P [15:35] ok, so we'll make sure everyone has juju installed and working in a bit... first of all, let's cover some basic concepts of charms with an example [15:36] I pulled a community-contributed charm off the list... just landed yesterday or the day before [15:37] so the first section we have is a basic listing of the charm contents [15:37] notice there're a couple of yaml files, a copyright, and then a set of scripts in the hooks/ directory [15:38] the scripts in the hooks/ directory are all in shell for this example [15:38] but juju takes great pains to be language/tool agnostic [15:39] you can use your fav toolset.. hooks just have to run and exit with return codes similar to a shell script ( 0 is good ) [15:39] so before we dig into the contents of the hooks [15:39] let's see what this charm is / does [15:39] take a look at the metadata [15:40] * m_3_ not a fast etherpad formatter :) [15:40] so it looks like the service described by this charm... [15:40] consumes a db (mysql in this case) [15:40] and presents a website [15:41] ok, that's pretty simple... and has a _lot_ in common with other services [15:41] so juju uses this metadata specification to stitch together different services [15:42] when juju spins a service unit up for this charm [15:42] it can 'relate' other services that match up [15:42] (does this by your command of course... but we'll get to the juju cli in a bit) [15:43] Any insight on where adding Rackspace support lies in the priority list for the juju project? [15:43] We're based in the UK and so UK IPs are a big must at the moment, which means AWS is out as they only have an Irish presence, nothing in the UK itself. [15:44] Otherwise, I'd be very interested in experimenting with juju, it sounds like an awesome project. [15:44] chmac: juju can handle a number of different providers [15:44] including openstack [15:44] so when juju spins up a service unit for this charm [15:44] the first hook it calls is 'install' naturally enough [15:45] please take a sec to look at the install hook in the pa [15:45] pad [15:45] starts off installing ppas and packages [15:46] it's worth noting here that juju charms can be used to install services that install from packages [15:46] but it can also be used to install other ways as well [15:46] you can clone directly from the tip of your source code repo if you'd like [15:46] anything goes [15:47] for charms contributed back to the community please prefer packages when available [15:47] but that's not necessary [15:47] so this particular charm adds ppas/and packages [15:47] then 'ch_get's a file from status.net [15:48] (this is one of marco's tools to download and cryptographically verify payloads in charms) [15:48] anyway... rest of the script is pretty clear [15:48] note the open-port at the bottom [15:49] juju defaults to everything closed off... you have to explicitly open what you want via the 'juju expose' command [15:49] so that's install [15:49] there're start/stop hooks too... these're usually trivial 'service xxx start' [15:50] so if you fail the open-port, there are iptables that prevent it? (firewall rules?) [15:50] correct [15:50] (not exactly iptables always) [15:50] depends on the provider [15:50] ah, aws / openstack port rules, gotcha. [15:50] (and still in development iirc on bare-metal provider) [15:51] so some charms are for services that just install a service and spin it up [15:51] some services don't relate to other services [15:51] and we'd be done if that were the case for status.net [15:51] here, we need a db [15:51] and we could potentially add a reverse-proxy in front of it [15:52] etc etc [15:52] so before we move on to relations... [15:52] any questions so far? [15:52] relations are the real meat of charms, so we'll pause here for questions [15:54] ok, on to relations!! [15:54] now this is the really cool part of juju... ok _a_ really cool part of juju [15:54] so when you look at the config for a service [15:55] you can often bust it up into "the config specific to installing that node" and "the config specific to relating to another service" [15:55] often the relation config info is a nice concise set of info [15:55] well juju uses these boundaries to 'install' as a separate step from 'relate' [15:56] so the basic story here is to [15:56] 1.) spin up status.net [15:56] 2.) spin up mysql [15:56] 3.) relate the two [15:56] 4.) expose status.net to the outside world [15:57] when we relate two services the charm hooks for those services exchange info [15:57] take a look at what's bold in the pad [15:57] that's an example of the status.net charm getting relation-specific config info from the mysql service [15:58] the mysql (db-relation-{joined,changed} hooks create a new db and credentials and then pass it to the service joining) [15:58]