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From Tyson Norris <tnor...@adobe.com.INVALID>
Subject Re: exporting activation arguments to the environment
Date Tue, 25 Jun 2019 22:07:10 GMT
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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