| `splunk-url` | required | Path to your Splunk Enterprise or Splunk Cloud instance (including port and schema used by HTTP Event Collector) `https://your_splunk_instance:8088`. |
| `splunk-capath` | optional | Path to root certificate. |
| `splunk-caname` | optional | Name to use for validating server certificate; by default the hostname of the `splunk-url` will be used. |
| `splunk-insecureskipverify` | optional | Ignore server certificate validation. |
| `tag` | optional | Specify tag for message, which interpret some markup. Default value is `{{.ID}}` (12 characters of the container ID). Refer to the [log tag option documentation](log_tags.md) for customizing the log tag format. |
| `labels` | optional | Comma-separated list of keys of labels, which should be included in message, if these labels are specified for container. |
| `env` | optional | Comma-separated list of keys of environment variables, which should be included in message, if these variables are specified for container. |
If there is collision between `label` and `env` keys, the value of the `env` takes precedence.
Both options add additional fields to the attributes of a logging message.