Where should you store the configuration data for the Config Server? The strategy that governs this behaviour is the EnvironmentRepository, serving Environment objects. This Environment is a shallow copy of the domain from the Spring Environment (including propertySources as the main feature). The Environment resources are parametrized by three variables:
{application}, which maps to spring.application.name on the client side.
{profile}, which maps to spring.profiles.active on the client (comma-separated list).
{label}, which is a server side feature labelling a "versioned" set of config files.
Repository implementations generally behave like a Spring Boot application, loading configuration files from a spring.config.name equal to the {application} parameter, and spring.profiles.active equal to the {profiles} parameter. Precedence rules for profiles are also the same as in a regular Spring Boot application: Active profiles take precedence over defaults, and, if there are multiple profiles, the last one wins (similar to adding entries to a Map).
The following sample client application has this bootstrap configuration:
bootstrap.yml
spring:
application:
name: foo
profiles:
active: dev,mysql
(As usual with a Spring Boot application, these properties could also be set by environment variables or command line arguments).
If the repository is file-based, the server creates an Environment from application.yml (shared between all clients) and foo.yml (with foo.yml taking precedence). If the YAML files have documents inside them that point to Spring profiles, those are applied with higher precedence (in order of the profiles listed). If there are profile-specific YAML (or properties) files, these are also applied with higher precedence than the defaults. Higher precedence translates to a PropertySource listed earlier in the Environment. (These same rules apply in a standalone Spring Boot application.)
You can set spring.cloud.config.server.accept-empty to false so that Server would return a HTTP 404 status, if the application is not found.By default, this flag is set to true.
