[cdi-dev] [JBoss JIRA] (CDI-504) have a standard CDI annotation like @ConfigProperty from deltapsike

Antoine Sabot-Durand (JIRA) issues at jboss.org
Mon Feb 9 05:54:50 EST 2015

    [ https://issues.jboss.org/browse/CDI-504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13038708#comment-13038708 ] 

Antoine Sabot-Durand commented on CDI-504:

I don't disagree with this idea but I have a few concerns or interrogations:

# As [~pmuir] stated Java have been including API for dealing with env and system property for a long time. So from my point of view here (and correct me if I'm wrong), is that the biggest interest of this feature would be typesafe injection of these config values and thus conversion from string to requested type. I understand that we would only provide a very limited set of supported type out of the box. But if we don't provide SPI to allow third party to add their own converter it could become source of frustration and it won't be in the "all is SPIable" spirit of CDI. So we open the door to include a converter SPI in the spec. I'm worried about the out of scope and anti-diet aspect of the spec here...
# In our discussion on Java SE boot in CDI-26 we have 2 {{init()}} method. One of them allows to boot the container with a parameter map {{init(Map<?,?> params)}}. What about these parameter from the config point of view? Are they only there to configure specific aspect of the container or could they be used also for configuration purpose?

> have a standard CDI annotation like @ConfigProperty from deltapsike
> -------------------------------------------------------------------
>                 Key: CDI-504
>                 URL: https://issues.jboss.org/browse/CDI-504
>             Project: CDI Specification Issues
>          Issue Type: Feature Request
>            Reporter: James Strachan
> Docker and containerisation is the new hotness; in the docker world images are static and the main way of injecting configuration is via environment variables - so that the same image can be reused but configured at run time with different configuration values. (Changing configuration files requires either different images to be created or using custom volumes which is less ideal in a containerized world).
> So IMHO CDI should provide a simple, natural way to allow environment variables (or system properties) to be easily injected via CDI.
> Delta Spike as a @ConfigProperty annotation which works very nicely
> http://deltaspike.apache.org/documentation/configuration.html
> you can specify a name, default value and use it on an @Inject to provide a value from env vars, system properties or provide a default.
> Given how core and useful this is - it feels like it should be part of the CDI specification; its one simple annotation.
> Currently deltaspike provides a way to configure different sources and whatnot which is cool; I'd be happy if CDI just had a simpler annotation which was only bound to env vars / system properties. 
> e.g. @EnvironmentProperty(name = "envvar", deafultValue="cheese")
> There could be debate on whether env vars or system properties should win if the same name is used for both; in a dockerized world I'd prefer env vars to win but folks can always tinker with their run command to make sure they pass in env vars as system properties to work around this I guess.

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