[Ur] Multitenancy

Sun May 13 14:02:49 EDT 2018

Thanks everybody for the help. I was running my exe in standalone mode, so
I didn't realise when you're running in fastCGI mode that Nginx will start
processes for you. As I said, I don't have any frame of reference so I ask
silly questions :).

As I see it now, I'll probably have an API endpoint "new_tenant" that will
run the following:

* Run a shell script to set up a new DB and load default data.
* Write the necessary config for a new fastCGI server with the new
connection string into my nginx config and reload nginx, as I've read this
should not impact the other servers. I'll probably add some notification to
myself whenever I do this so I don't silently start thousands of servers
when something goes wrong.

It would be nice if I could have urweb do this. Is there a way to run shell
scripts for urweb? And what about interacting stuff with file system? Both
I have not seen happen in urweb, since it's mostly not necessary. Am I
better off using the FFI for these things? I saw the BazQux reader uses the
FFI to call into Haskell, that seems very nice even though it's probably
overkill for this use case.

Simon

2018-05-13 16:13 GMT+02:00 Rob Manhatton <rob.manhatton at gmail.com>:

> After a light google, it seems that terraform's linode support isn't super
> mature yet, so if you're comfortable doing all the apps on the same VM and
> database end point then hold off on terraform a few more months (although
> you will really like having nearly 100% of your systems backed by code when
> you have bandwidth to look into it).
>
> On May 13, 2018 9:03:28 AM CDT, Adam Chlipala <adamc at csail.mit.edu> wrote:
>
>> I'm not sure which aspect of deployment you're worried about.  With
>> Apache, you can configure as many FastCGI applications as you'd like, and
>> they will all be started automatically on each reboot.  It only takes a few
>> lines of configuration per application.  Similarly, creating a new database
>> is a few lines of shell script, using the .sql file that the Ur/Web
>> compiler produces for an application.  All of the details are independent
>> of application specifics.
>>
>> I am not aware of any existing tools for doing these simple steps
>> automatically, but it should be easy to roll an all-inclusive shell script.
>>
>> On 05/13/2018 09:48 AM, Simon Van Casteren wrote:
>>
>> I considered it briefly as I was doing some research on the topic. It's
>> the first time I'll be running and deploying a SaaS app myself (I've so far
>> always been on the programming side only) so it felt more natural to me to
>> keep everything inside a single application. Running the application right
>> now consists of me ssh'ing into a Linode and running the exe by hand. If I
>> want to split this into one application per database (which does guarantee
>> data security better, that's really nice) then deployment seems to become
>> much more complicated.
>>
>> But let's say I do go that route. Is using one of the new deployment
>> tools a good idea for a just-started scenario? I appreciate how ur/web uses
>> very basic and simple tools, eg: Using curl in the Worldffi project to do
>> HTTP requests, not having editor tooling but having the compiler use
>> standard error formatting so emacs picks it up automatically. This is in
>> strong contrast to the javascript community where I normally reside, which
>> likes to re-implement things a lot. So I'd like to know what advice the
>> community has on the right tools for setting up a new application and
>> database automatically (probably via the C FFI?) and then running and
>> updating them together. I would like to note that adding and running new
>> clients without any manual work is strongly preferred.
>>
>> Because I don't have any idea of how I would handle this adding and
>> deploying of clients, I can't weigh the two alternatives: Complicating the
>> app with tenantIds, or complicating the deployment with seperate apps.
>>
>> 2018-05-13 15:31 GMT+02:00 Adam Chlipala <adamc at csail.mit.edu>:
>>
>>> Can you explain why you don't want to run separate applications with
>>> separate databases?
>>>
>>>
>>> On 05/13/2018 05:50 AM, Simon Van Casteren wrote:
>>>
>>> Hi,
>>>
>>> I'm in the process of making a new application for music schools, using
>>> ur/web for front and backend. I'm at the point where I have two customers
>>> and am starting to implement support for multiple clients/tenants in one DB
>>> (postgres). I've been planning to implement multitenancy from the start,
>>> but haven't had the time yet.
>>>
>>> Has anyone implemented a form of multitenancy in ur/web before?
>>>
>>> I see two areas that need consideration.
>>>
>>> 1. Deciding which user belongs to which tenant. Ideally I'd have a
>>> seperate url for each tenant that I can give out to my clients (=the
>>> schools), do some dns magic to send them all to the same exe, extract the
>>> tenantname from the url and save the tenantId in a cookie. Also ideally,
>>> the user's url would not change, ie. All urls should go to
>>> myschool.coolschools.be during a session, not getting redirected at
>>> all. This is all in an ideal situation of course.
>>>
>>> 2. Database access: I'll have tenantId columns in all tables + foreign
>>> keys and indexes on these columns. I'm a bit afraid I'll forget adding
>>> tenantId = cookie.tenantid somewhere, so I was thinking I could make a
>>> function that takes a sql_exp and a tenantId and adds these clauses to all
>>> tables involved. Not 100% sure that will work but I think it's possible, I
>>> haven't had to dive into the internals of sql_exp yet. Secondly, I wonder
>>> if I can somehow declare my endpoints to be tenantdepandent (all but the
>>> most general will be) maybe via newtyping the transaction datatype and then
>>> allowing the execute only sql queries that have the above function applied.
>>> Just dreaming out loud here.
>>>
>>> I'd be very interested in any ideas or examples!
>>>
>>> Simon
>>>
>>>
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