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zio / zio-config

Easily use and document any config from anywhere in ZIO apps
https://zio.dev/zio-config
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System properties are ignored when using Hocon files/strings #419

Open BernardMarshall opened 3 years ago

BernardMarshall commented 3 years ago

The parsing of the Hocon files and strings use the ConfigFactory.parseFile and ConfigFactory.parseString methods. Both these methods load the configuration but do not include the system properties. Hence if you have substitutions of the form ${?app.config} in your Hocon file/string then the substitution is not resolved if the value is set in the system properties. To have the system properties loaded a call to ConfigFactory.defaultOverrides is required.

A possible fix (in TypesafeConfigSource.scala) is to change:

def fromHoconFile[A](
    file: File
  ): Task[ConfigSource] =
    IO.effect(ConfigFactory.parseFile(file).resolve)
      .flatMap(typesafeConfig => {

to be:

def fromHoconFile[A](
    file: File
  ): Task[ConfigSource] =
    IO.effect(ConfigFactory.defaultOverrides.withFallback(ConfigFactory.parseFile(file)).resolve)
      .flatMap(typesafeConfig => {

A similar change could be added to the fromHoconString method. The change ensures system properties are resolved correctly in Hocon files/strings.

afsalthaj commented 3 years ago

Another way of doing it is using orElse combinator in ConfigSource.

descriptor[MyConfig] from source1.orElse(source2)

BernardMarshall commented 3 years ago

Thanks for the reply. Yes that is possible. It just means moving the ${?app.config} markers out of the Hocon file and into a config descriptor so that the system properties can be used. Not a big deal, but it is nice to have the markers in the Hocon file as it "documents" how a config property can be set.

afsalthaj commented 3 years ago

Sure.we will definitely see if we can fix this issue. Meanwhile, generateDocs(descriptor).toTable.asGithubFlavouredMarkdown can give us a doc and a list of sources associated with each parameter. See if it’s of any help

On Fri, 27 Nov 2020 at 10:04 AM, Bernard Marshall notifications@github.com wrote:

Thanks for the reply. Yes that is possible. It just means moving the ${?app.config} markers out of the Hocon file and into a config descriptor so that the system properties can be used. Not a big deal, but it is nice to have the markers in the Hocon file as it "documents" how a config property can be set.

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