use a config struct instead of a raw global in main.go

[flbn]

          also, this is separate but how do we feel about using a struct instead of this global variable?

like, instead of this:

var (
    runtimeAPI        = os.Getenv("AWS_LAMBDA_RUNTIME_API")
    extensionName     = filepath.Base(os.Args[0])
    isFirstInvocation = true
    runtimeDone       = make(chan struct{})

    // API Port
    logsPort = "8080"

    // Buffering Config
    defaultMaxItems  = 1000
    defaultMaxBytes  = 262144
    defaultTimeoutMS = 1000

    developmentMode = false
    logger          *zap.Logger
)

something more like:

type Config struct {
    RuntimeAPI        string
    ExtensionName     string
    IsFirstInvocation bool
    LogsPort          string
    MaxItems          int
    MaxBytes          int
    TimeoutMS         int
    DevelopmentMode   bool
    Logger            *zap.Logger
    RuntimeDone       chan struct{}
}

var cfg = Config{
    RuntimeAPI:        os.Getenv("AWS_LAMBDA_RUNTIME_API"),
    ExtensionName:     filepath.Base(os.Args[0]),
    IsFirstInvocation: true,
    LogsPort:          "8080",
    MaxItems:          1000,
    MaxBytes:          262144,
    TimeoutMS:         1000,
    DevelopmentMode:   false,
    RuntimeDone:       make(chan struct{}),
}

and then used like

cfg.Logger.Error('ex')

Originally posted by @flbn in https://github.com/axiomhq/axiom-lambda-extension/issues/17#issuecomment-1737615992