This change introduces logging.timestamp_format, which allows
configuration of the Logrus TimestampFormat setting. The primary purpose
of this change was to allow logging with millisecond precision. The
default for `text` and `json` formats remains the same for backwards
compatibility.
timestamp format is specified in Go time format, see:
- https://golang.org/pkg/time/#pkg-constants
Default when `format: json`: "2006-01-02T15:04:05Z07:00" (RFC3339)
Default when `format: text`:
when TTY attached: seconds since beginning of execution
otherwise: "2006-01-02T15:04:05Z07:00" (RFC3339)
As an example, to log as RFC3339 with millisecond precision, set to:
logging:
timestamp_format: "2006-01-02T15:04:05.000Z07:00"