go-cli

Place one file per command under cmd/myapp/, keep main.go limited to calling Execute(), and initialize Viper config in the root command's PersistentPreRunE. Bind every configurable flag with viper.BindPFlag under a SetEnvPrefix namespace.

Use Cobra with Viper for anything with subcommands, layered config, or completions. Reserve the stdlib flag package for trivial single-purpose tools with no subcommands, where pulling in Cobra adds unnecessary weight.

Write program output only to stdout via cmd.OutOrStdout() and send logs, errors, and diagnostics to stderr. Add an --output flag supporting json, table, and plain formats so scripts can parse results reliably.

Inject version, commit, and date via go build -ldflags -X flags from git tags, then expose them through a version subcommand. Avoid hardcoded version strings so releases always report accurate build metadata.

Calling os.Exit inside RunE skips Cobra's error handling and deferred cleanup. Return errors from RunE instead, let main() decide the exit code, and set SilenceUsage so usage text only prints with --help.

No. Ignore viper.ConfigFileNotFoundError when reading config so the file stays optional. Precedence remains CLI flags first, then environment variables, then config file, then code defaults.