additional catering towards the application developer

Fri Dec 11 05:02:46 UTC 2015

Merlin,

    Adding a wrapper around juju action may have been the first juju
related code that I wrote.

function jujuaction {
    time=$1
    shift
    echo juju action do $@
    tmp=`juju action do "$@" |cut -f2 -d:`
    printf "${tmp} "
    while true; do
        sleep $time
        juju action status $tmp |grep -E "status: (pending|running)"
>/dev/null || break
        printf "."
    done
    echo ""
    juju action fetch $tmp
}

  Looking at the help for juju I would ask/prefer that waiting for an
action or parsing a result would be done with new commands sent to juju
action.

usage: juju action [options] <command> ...
purpose: execute, manage, monitor, and retrieve results of actions

options:
--description  (= false)

-h, --help  (= false)
    show help on a command or other topic

"juju action" executes and manages actions on units; it queues up new
actions,
monitors the status of running actions, and retrieves the results of
completed
actions.

commands:
    defined - show actions defined for a service
    do      - queue an action for execution
    fetch   - show results of an action by ID
    help    - show help on a command or other topic
    status  - show results of all actions filtered by optional ID prefix
wait - run an action and return all of the results
parse - run an action and return the results matching a result string or
dict

Example Usage:
juju action wait <unit> <params>
juju action parse <unit> <params> result=Œavg.latency'

Regards,
Matt Dirba
512.779.4696

>
>Message: 6
>Date: Wed, 9 Dec 2015 17:13:09 -0500
>From: Adam Stokes <adam.stokes at canonical.com>
>To: Merlijn Sebrechts <merlijn.sebrechts at gmail.com>
>Cc: juju <juju at lists.ubuntu.com>
>Subject: Re: additional catering towards the application developer
>Message-ID:
><CAKorV6wUZJzh=0nvUEsmhDT9OKWTUA2fw_uKV_b11fW_aTM2Gw at mail.gmail.com>
>Content-Type: text/plain; charset="utf-8"
>
>Also there seems to be a couple of bugs relevant to this discussion:
>
>https://bugs.launchpad.net/juju-core/+bug/1445066
>https://bugs.launchpad.net/juju-core/+bug/1445078
>
>On Wed, Dec 9, 2015 at 5:09 PM, Adam Stokes <adam.stokes at canonical.com>
>wrote:
>
>> I agree, having the ability to run actions synchronously and wait for a
>> result  would be a huge step in allowing charm authors to provide
>>actions
>> that can be used during the development of your application _before_ you
>> reach the stage of charming that app.
>>
>> Casey, made a suggestion of possibly making the actions more relevant to
>> the type of task it's running (background vs run-and-wait). For
>>example, to
>> launch an action in the background you could do `juju action launch
>>(begin,
>> start)` and to run an action immediately and wait for the result would
>>be
>> `juju action do` or even drop the word `action` and have it be `juju
>> launch` and `juju do`. Semantics aside though I think this would be an
>> excellent addition and first step for getting application developers
>> interested in bringing their application into the Juju ecosystem.
>>
>> On Wed, Dec 9, 2015 at 4:48 PM, Merlijn Sebrechts <
>> merlijn.sebrechts at gmail.com> wrote:
>>
>>> I've been thinking about the actions as well. 99% of the actions
>>>use-case
>>> is: Run the action, wait for it to finish and show the result. Most of
>>>the
>>> actions are things like 'restart', 'show-something',...
>>>
>>> I think waiting for the action to finish and show the result should be
>>> put in as a flag, with the possibility to become default in Juju2.
>>>
>>> - Juju 1: Add flag --wait
>>> - Juju 2: Make --wait default and add flag --no-wait
>>>
>>>
>>> What do you guys think? Is this what you had in mind, Adam?
>>>
>>> 2015-12-09 18:28 GMT+01:00 Adam Stokes <adam.stokes at canonical.com>:
>>>
>>>> I wanted to write this to get a discussion going around how we can
>>>>better
>>>> support application developers. This is something I've been thinking
>>>> about
>>>> for awhile and was further convinced to write this email after seeing
>>>> posts
>>>> like:
>>>>
>>>>http://askubuntu.com/questions/635758/is-juju-a-suitable-tool-for-devel
>>>>opment-as-well-as-deployment
>>>>
>>>> The scenario:
>>>>
>>>> In its simplest form, I am writing a web application that needs a
>>>> database. I
>>>> would like to quickly startup a postgresql server and grab it's
>>>> connection
>>>> information.
>>>>
>>>> How's its done with docker:
>>>> $ docker pull k0st/alpine-postgres
>>>> $ docker run --name myapp -e POSTGRES_USER=user -e
>>>> POSTGRES_PASSWORD=password -e POSTGRES_DB=testdb k0st/alpine-postgres
>>>> $ docker inspect --format '{{ .NetworkSettings.IPAddress }}' myapp
>>>> 172.16.0.5
>>>>
>>>> From here you can build your connection string:
>>>> postgresql://user:password@172.16.0.5:5432/testdb
>>>>
>>>> And now how we could possibly accomplish this with Juju today:
>>>>
>>>> 1. Using Juju actions:
>>>>
>>>> $ juju deploy postgresql
>>>> $ juju action do postgresql/0 createdb username=user password=pass
>>>> database=testdb
>>>> Action queued with id 32432-432-432-432-432-432
>>>> $ juju action fetch 32432-432-432-432-432-432
>>>>
>>>> .. Parse the results
>>>>
>>>> message: "" # No error message.
>>>> results:
>>>>   result-map:
>>>>     connection_string: postgresql://user:pass@
>>>> <unit-public-address>:5432/testdb
>>>>     message: Hello world!
>>>>   outcome: success
>>>> status: completed
>>>>
>>>> 2. Adding support in the charm hook (config-changed)
>>>>
>>>> $ juju deploy postgresql
>>>> $ juju set postgresql "createdb=user:pass:dbname"
>>>>
>>>> .. config-changed
>>>>
>>>> status-set "active", "db created:
>>>> postgresql://user:pass@unit-public-address:5432/dbname"
>>>>
>>>> $ juju status postgresql
>>>>
>>>> Look for the status message in the output.
>>>>
>>>> As you can tell between docker and juju we're still looking at 3
>>>> commands for
>>>> just standing a database up, creating the db, and getting its
>>>>connection
>>>> details.
>>>>
>>>> It would be really nice if I could just do:
>>>>
>>>> $ juju deploy postgresql
>>>> $ juju postgresql create-db --username=user --password=pass
>>>> --database=mydb
>>>>
>>>> # Default to json output for our application to consume and make use
>>>>of
>>>> {"error": "", "result": "postgresql://user:pass@unit-public-address
>>>> :5432/mydb"}
>>>>
>>>> Even an action would still be ok if the action would print the results
>>>> to stdout
>>>> $ juju action do postgresql/0 create-db username=user password=pass
>>>> database=mydb
>>>> {"error": "", "result": "postgresql://user:pass@unit-public-address
>>>> :5432/mydb"}
>>>>
>>>> For me, personally, I don't want to use docker or vagrant or any other
>>>> tool as
>>>> I feel Juju is fully capable of catering to the application developer.
>>>>
>>>> Thoughts?
>>>>
>>>> --
>>>> Juju mailing list
>>>> Juju at lists.ubuntu.com
>>>> Modify settings or unsubscribe at:
>>>> https://lists.ubuntu.com/mailman/listinfo/juju
>>>>
>>>>
>>>
>>

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