Support external configuration files

[alexandre-touret]

Hello, In addition of this issue, it could be nice to support external configuration files. I usually externalize all the configuration files from WAR/JAR in order to handle multi environment deployments with the same artifact ( DEV -> PROD ).

For instance, when we run the application, I could apply the configuration files as following :

java -jar my_app.jar -Dconfig=microservice-config.properties

Thanks Regards Alexandre Touret

[pilhuhn]

Like for #418 please use a prefix of e.g. -Dconfig.fromFile and not only `-Dconfig´ in case this is implemented.

[dmlloyd]

Relying on a system property can be problematic, if more than one application exists in the run time. Does the external file then apply to all configurations? How does one exclude it? Etc.

I think the container ought to be responsible for providing this feature because sometimes it will make sense and sometimes it will not.

[Emily-Jiang]

We discussed this issue at today's hangout with @jmesnil @kenfinnigan. This sounds a good approach to feed in config properties at different stage.

[Emily-Jiang]

What is the default ordinal for this file if the file itself does not define the property ordinal? @jmesnil suggested to use 400-1. Thoughts?

[alexandre-touret]

Hello, Thanks for your feedback.

I have a question : Why 400-1 and not 500 ?

Regards

[dmlloyd]

You want more space than just one to allow user-defined sources to be inserted in between config sources. The point of specifying spacing between config source ordinals in the specification is to do exactly that.

[dmlloyd]

Also, this feature really can't be implemented until the above questions are answered.

[Emily-Jiang]

Relying on a system property can be problematic, if more than one application exists in the run time. Does the external file then apply to all configurations? How does one exclude it? Etc.

If more than one apps for this server, this configuration should applicable to each app. Each application should create one config source object of course.

[dmlloyd]

We don't presently have a way for a configuration source to use other configuration sources to configure themselves. See #470 for more info.

[Emily-Jiang]

I have a question : Why 400-1 and not 500 ?

Since system property is having the ordinal of 400, when you pass in the configsource via the command line, you might want to override the system properties. Personally, I think having the default ordinal of 500 makes sense. By the way, you can config this ordinal by adding a property of config_ordinal in the config source.

[Emily-Jiang]

maybe use 450 as the ordinal_value to allow more config sources to squeeze in. How about -Dconfig.location=, which could be a file or a folder. Thoughts?

[Emily-Jiang]

@littlewing we discussed today. Will #418 solve your issue? If not, can you specify your use case clearly so that we can understand what you are trying to achieve?

[alexandre-touret]

Hello @Emily-Jiang . Thanks for your feedback. From what I understood #418 only mentions internal configuration files. I think that project stages is an interesting feature. However, the use cas I described is to use external files (for instance provided by config maps in K8S). In addition to your last comment , I guess that defining the property -Dconfig.location= as a file location could be a good idea.

I'm available for further informations if needed.

Regards

[radcortez]

Hi @littlewing

Not exactly. While #418, gives the idea to apply profiles to files, it wouldn't be specced that way because of obvious limitations. The current proposal is to support them at the configuration level, so this will allow you to specify any profile in any ConfigSource and not only file based config sources.

[alexandre-touret]

OK got it. It sounds good for me.

[radcortez]

With the current proposal of #418, will it be enough for your use case @littlewing ?

[alexandre-touret]

If the #418 proposal enables using any ConfigSource even from external sources then I will be "enough".

Thanks

[radcortez]

Yes, that the idea. Thank you :)

[smillidge]

@littlewing this is easily done with a custom ConfigSource that reads property files. Payara Micro supports that through --systemproperties <file-path>

I suppose a bigger question is whether we want to specify more config sources?

[OndroMih]

@littlewing, I don't see how #418 solves this? #418 adds an option to specify different values for different profiles for the existing config sources. It won't allow reading values from an external config file. For that, we would have to define an additional standard config source so that you don't have to rely on a non-standard config source like @smillidge described.

418 only allows creating an additional properties file inside the app that would be used when a specific profile is selected. Alternative proposal would allow specifying profile-specific values in config sources. There are only 3 standard config sources: properties files inside the app, system properties and environment variables.

Or am I wrong and I just don't see how #418 solves your usecase? Can you explain?

[alexandre-touret]

Hello, Maybe I'm wrong, but @radcortez said in this comment that #418 could fit my needs. If I can enable loading some configuration values from an external file ( for instance a file provided by a k8s config map) by enabling a profile or whatever, it's OK for me. The payara micro feature described by @smillidge is good also.

[Emily-Jiang]

If I can enable loading some configuration values from an external file ( for instance a file provided by a k8s config map) by enabling a profile or whatever, it's OK for me.

You can do it today by specifying config properties in k8s config map and directly map the configmap to env, which makes all config properties available to your microservices. e.g.

kubectl create configmap greeting-config --from-literal message=Hello

In k8s deployment yaml:

env:
- name: GREETING
valueFrom:
configMapKeyRef:
name: greeting-config
key: message

What I would also want to mention here. There is another support I would like to propose for #418 is to support config source overriden at a file level. Considering you have a jar with META-INF/ containing the following 3 files:

microprofile-config.properties
microprofile-config-dev.properties
microprofle-config-live.properties

if mp.config.profile=dev, the file microprofile-config-dev.properties will be loaded while the other two will be ignored. In this way, end users can easily support different values for config properties based on the project profile.

[Emily-Jiang]

I think what you proposed is to automatically load a config source without doing the service loader patter and directly load that all properties contained in a config source. At the moment, you can use -Dmy.config.prop1=blah, which allows you to add system properties on microservice startup.

You want to load a whole file and treat all properties inside the file as config properties instead of specifying individual config properties. @smillidge mentioned to load the files as system properties in Payara, we could also load the config source as a config source other than system properties with the specified config source ordinal.

[alexandre-touret]

Hello,

I think what you proposed is to automatically load a config source without doing the service loader patter and directly load that all properties contained in a config source. At the moment, you can use -Dmy.config.prop1=blah, which allows you to add system properties on microservice startup.

For few properties it's OK, when you have several properties, it could be a nightmare to deal with.

You want to load a whole file and treat all properties inside the file as config properties instead of specifying individual config properties. I "only" want that feature. As I said in the issue description, I would like to specify the config file directly from the command line:

java -jar my_app.jar -Dconfig=microservice-config.properties

[radcortez]

To understand better, should a file passed in -Dconfig just overrides the location of microprofile-config.properties and still have the same ordinal in the config sources, or should it also override any property?

For what it seems, you want the ability to pass a file, but also override?

[alexandre-touret]

Hello, Frankly I didn't consider these constraints. I only wanted to pass a file. However, I think that the ability to override a whole file or some properties is interesting.

Just as a comparison, the existing spring boot analog feature is really useful on a daily basis (for devs and ops).

[Emily-Jiang]

To understand better, should a file passed in -Dconfig just overrides the location of microprofile-config.properties and still have the same ordinal in the config sources, or should it also override any property?

From my understanding, -Dconfig=fully.qualified.propertie.file. It supplies a fully qualified property file and it has no clash with microprofile-config.properties. It just adds additional properties. The file itself has its own ordinal (containing config_ordinal property inside the property file).

For what it seems, you want the ability to pass a file, but also override?

It just provides a way to pass in the config file instead of creating service loader for it.

[Emily-Jiang]

To summarise this issue, I would like to make the following proposal is:

1. Reserve a special config property included.config.location with the fully qualified property file
2. When a property is found, while the property can be specified as a system property or environment variable or a property in other config sources, MP Config automatically load that property file. The properties inside included.config.location will be merged into the parent. If it contains the same property as the parent property, the property inside included.config.location overrides the same property in the parent parent. If included.config.location contains config_ordinal, that property will be ignored. In this way, when you use java -jar myjar.jar -Dnested.config.location=/etc/myworld.properties, the properties inside that file will be treated as other system property, as it inherits the parent nature.

e.g. system properties

java.version=1.8
os.name=Mac OS X
included.config.location=/etc/myExtraConfig.properties, /etc/myAnoterConfig.properties

/etc/myExtraConfig.properties

client.name=Bob
client.age=21

The system property config source will have the following properties

java.version=1.8
os.name=Mac OS X
client.name=Bob
client.age=21

@alexandre-touret does this solve your problem?

[alexandre-touret]

Hello, Sorry for the delay.

Thanks @Emily-Jiang for your proposal. It solves my problem.

Regards

[jbee]

@Emily-Jiang you did not fully update your example in https://github.com/eclipse/microprofile-config/issues/422#issuecomment-646698208 consistently using included.config.location as the special property reserved for includes of one or more fully qualified files.

[Emily-Jiang]

@jbee thanks, I have now updated all occurences.