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From Tyson Norris <tnor...@adobe.com.INVALID>
Subject Re: exporting activation arguments to the environment
Date Wed, 26 Jun 2019 18:07:28 GMT
Sorry, it still seems controversial to me, not sure how others feel?

To be clear, when you added "-a  partition-arguments true", the result is 2 things:
1. some of the -p args are now treated different than others - can you confirm this is decided
based on the case of the parameter name?
2. init receives these params (which sounds good to me). 

Regardless of opting in to this behavior, having action-configured parameters referenced differently
based on the name of the param seems bad.  I understand there are some useful conventions
defining these as env vars, but my point is that this doesn't seem at all like an explicit
choice. I think an explicit choice would be more like adding a '-e' flag that specifically
does "set these environment variables", instead of overloading the '-p' flag with a convention
based on the name of the variable.

Thanks
Tyson


On 6/26/19, 10:43 AM, "Rodric Rabbah" <rodric@gmail.com> wrote:

    Maybe this got missed, but here's how I conceived of this. I'll use wsk CLI
    commands, I think it makes it obvious.
    
    wsk action create myAction code.js -p MY_ENV true -p some_param false -a
    partition-arguments true
    
    The annotation (partition-arguments) makes it explicit for the developer to
    control whether "main" receives the arguments as they do today, which is
    this object
    { MY_ENV: true, some_param: false}, or when the annotation is true, {
    some_param: false} and process.env.MY_ENV is set to true.
    
    I don't think there's anything confusing about this in that the developer
    has decided what variables to export to the environment, and is making an
    explicit choice.
    
    Environment variables on a number of platforms are restricted to those at
    consist of words that start with capital letter (AWS, Netlify as two prime
    examples).
    
    The alternative, today, requires a function to export any variables from
    "main" to the environment. So it would explicitly export MY_ENV to the
    environment. The change we're discussing frees the programmer from having
    to do that.
    
    The change to the runtime proxies would be 1. accept an additional value on
    /init and export all the properties it contains to the environment.
    
    Before I address the POST invoke issue, I'd like to make sure my
    explanation is clearer and if this is still controversial.
    
    -r
    
    
    On Wed, Jun 26, 2019 at 1:21 PM Tyson Norris <tnorris@adobe.com.invalid>
    wrote:
    
    > Are you saying one is exported to environment, during init, based on
    > parameter name being UPPER case? Forgetting use of env vars for a minute,
    > this seems confusing to treat parameters different based on names. I would
    > rather see either a) all action-configured params sent to init only, and
    > never to run or b) all action-configured params sent to run as context
    > object.
    >
    > What the runtime does at init (use env vars or not) can be different per
    > runtime, but in the action-configured parameter case I don't see any
    > problem with setting env vars, except that there seems to be a convention
    > in some cases that allows invoking clients to "override" these values using
    > POST parameters at invocation time. This also seems confusing but could
    > also be enforced differently by various runtimes, although ideally I would
    > rather see the convention change to: action-configured parameters are
    > always sent to init, and always visible to run, regardless of what client
    > sends as execution parameters.
    >
    > Thanks
    > Tyson
    >
    >
    > On 6/25/19, 3:32 PM, "Rodric Rabbah" <rodric@gmail.com> wrote:
    >
    >     Context and Knative I view as orthogonal.
    >
    >     That is, for the context object, it is another way of encapsulating
    > arguments. It doesn’t export variable to the process environment.
    >
    >     You can provide an action with both environment variables, arguments
    > to main, and a context object. They are orthogonal.
    >
    >     For the context object, the distinction that was necessary from
    > previous discussions was related to separating intra container concurrent
    > executions. If the system-provided context is exported to the environment
    > as it today the values clobber each other. For this, the context object
    > would make sense.
    >
    >     I’m simply talking about two parameters wsk ... “-p a A” and “-p B b”
    > say where one becomes exported to the environment as B=b and the other is
    > passed to the action as ({a:A}).
    >
    >     I’m going to set the knative discussion aside because I think it’s a
    > distraction. With knative you can bind environment variables to the
    > container. As you would with any other container.
    >
    >     I think it’s too simplistic to say knative has a single endpoint.
    > After all there are readiness probes and possible pre/post start hooks that
    > operators may have to deal with. Init can be viewed as the readiness probe.
    >
    >     Fundamentally I believe the actor model is much better aligned with
    > the reactive programming model for functions so this will tend toward a
    > completely different discussion in my view.
    >
    >     The reason my proposal sets the environment variables at init time is
    > that’s how env vars work;  they exist before you start you process. While
    > they don’t need to be immutable, it makes sense to test them as such.
    >
    >     For webaction parameters that one would export to an environment, they
    > are already immutable and cannot be overridden. So really you would not use
    > them for anything that varies per activation.
    >
    >     The view here is that you can export global (immutable) variables to
    > the action. This makes it easier to take existing code and containers which
    > might use env vars and use them almost off the shelf.
    >
    >     -r
    >
    >     > On Jun 25, 2019, at 6:07 PM, Tyson Norris <tnorris@adobe.com.invalid>
    > wrote:
    >     >
    >     > I had to read this several times, but have some suggestions. I think
    > when you say "action's arguments", you mean action-configured params, e.g.
    > `wsk action create --param p1 v1`?
    >     >
    >     > My preferences would be:
    >     > - we should split off "run" args into context and params - this is
    > the convention change for redefining main(args) as main(context, args) we
    > have discussed in the past.
    >     > - I support either having init receive action-configured params
    >     > - activation args that are possibly overridden should behave exactly
    > as specified args - is it important that action-configured args are
    > actually overridden, if the context and params are separated? (receive both
    > values, and logic must decide when to use which)
    >     > - let's not use env variables for any arg that is variable per
    > activation - it is impossible if you support concurrency, and unneeded if
    > we pass the context to "run".
    >     >
    >     > Regarding Matt's suggestion to remove init - I like this idea, but I
    > have concerns compared to knative which might serve every function with a
    > different container, vs having some containers reused for multiple
    > functions. In the case where we init code into an already running
    > container, it is useful to have the init process separate from run, since
    > otherwise each runtime will need to track its own init state and queue
    > requests during init etc. If I'm not getting the whole picture with
    > knative, please correct me.
    >     >
    >     >
    >     > Thanks
    >     > Tyson
    >     >
    >     > On 6/24/19, 8:43 AM, "Rodric Rabbah" <rodric@gmail.com> wrote:
    >     >
    >     >    In the current activation model, an action's arguments are always
    > provided
    >     >    to the action on "run", not "init".
    >     >
    >     >    Should we consider partitioning the argument list into two sets,
    > the first
    >     >    is exported as environment variables at "init" time, and the
    > second become
    >     >    the action's argument at "run" time? A criteria for partitioning
    > is that
    >     >    the environment variable starts with a capital letter, which is a
    > common
    >     >    convention.
    >     >
    >     >    For example, an action which is invoked with a JSON object
    >     >
    >     >    { "XYZ": true,
    >     >      "abc" : false }
    >     >
    >     >    would receive {"abc": false} as its arguments and can read XYZ
    > from the
    >     >    environment (as process.env.XYZ == "true" in Node.js).
    >     >
    >     >    This change would:
    >     >    1. require a change in the invoker to pass arguments during
    > initialization
    >     >
    >     >    2. require a change in the runtime proxies to export the
    > arguments to the
    >     >    environment at initialization time (additional work may be
    > implied by 1b)
    >     >
    >     >    3. an annotation on actions to opt into this partitioning for
    > backward
    >     >    compatibility or to opt out. For example '-a
    > env-partition-arguments true'
    >     >    partitions the arguments and actions without this annotation are
    > not
    >     >    affected.
    >     >
    >     >    Some obvious question:
    >     >    Q1a. should the invoker perform the partitioning or delegate it
    > to the
    >     >    runtime? The advantage of the former is that the runtimes do not
    > have to
    >     >    implement the filtering policy and do less work. I think it makes
    > sense to
    >     >    do this invoker side for uniformity.
    >     >
    >     >    Q1b. should the partitioning treat environment variables as
    > immutable post
    >     >    init and ignore the partition on warm starts? This is an issue
    > when a value
    >     >    is overridden during POST invoke only since for a webaction, you
    > cannot
    >     >    override a value that's already defined (and updating a bound
    > parameter on
    >     >    an action invalidates warm containers). I think env vars should
    > be treated
    >     >    as immutable despite the issue with POST invoke.
    >     >
    >     >    -r
    >     >
    >     >
    >
    >
    >
    

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