Question 1

How to set default values for environment variables in envconfig?

Accepted Answer

Use the `default` struct tag in your Go struct, e.g., `DefaultVar string `default:"foobar"``. This sets the value to "foobar" if the environment variable is absent, as shown in the struct tag support section of the README.

Question 2

envconfig vs viper: which is better for Go configuration?

Accepted Answer

envconfig is simpler and ideal for pure environment variable use in 12-factor apps, while Viper supports multiple config sources like files and flags but is heavier. Choose envconfig for focused environment variable loading, Viper for broader config management needs.

Question 3

How to handle nested structs with envconfig?

Accepted Answer

Embed structs directly in your configuration struct; envconfig automatically processes them hierarchically. Use prefixes to namespace variables, as demonstrated in the embedded structs and prefix management features of the README.

Question 4

Can envconfig load configuration from JSON or YAML files?

Accepted Answer

No, envconfig is designed specifically for environment variables. For file-based config, you need to use another library to load environment variables from files first, or switch to a tool like Viper that handles multiple sources.

Question 5

How to implement custom decoders in envconfig?

Accepted Answer

Implement the `envconfig.Decoder` interface with a `Decode(value string) error` method. The README provides examples, such as decoding IP addresses or complex maps, showing how to add custom deserialization logic.

Question 6

What happens if a required environment variable is empty in envconfig?

Accepted Answer

Envconfig does not treat empty values as missing; it only errors if the variable is absent. For empty values, you may need manual validation, as the `required:"true"` tag only checks for existence, not content, per the struct tag documentation.

envconfig

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