Question 1

How to load environment variables with fig in Go?

Accepted Answer

Use the UseEnv option when calling fig.Load, specifying a prefix for env vars. For example, fig.Load(&cfg, fig.UseEnv('APP_')) loads environment variables with that prefix, and they take precedence over file values.

Question 2

Fig vs Viper: which should I use for Go configuration?

Accepted Answer

Fig is simpler and lighter, ideal for basic file and env var loading with type safety. Viper offers more features like remote config, hot reload, and broader format support, but with more dependencies and complexity.

Question 3

How to set default values in fig?

Accepted Answer

Define defaults directly in struct tags using the 'default' attribute, as shown in the README example where fields like Host have default values that apply if not set in the config file.

Question 4

Does fig support YAML configuration files?

Accepted Answer

Yes, fig supports YAML, JSON, and TOML file formats natively, allowing you to define your configuration in any of these formats and load them into Go structs without additional setup.

Question 5

Can fig validate required configuration fields?

Accepted Answer

Yes, by using the 'validate:required' tag on struct fields, fig checks that these fields are not empty after loading, ensuring essential config is present, though validation is basic.

Question 6

How to handle nested structs in fig configuration?

Accepted Answer

Nested structs are supported by defining them within the parent struct, and fig will recursively load the configuration, as demonstrated in the Server and Logger sub-structs in the README example.

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