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| `ENABLE_BOOTSNAP` | string | Toggles [Bootsnap](https://github.com/Shopify/bootsnap) for speeding up initial Rails boot. Enabled by default for non-production environments. Set to `0` to disable. |
| `EXTERNAL_URL` | string | Specify the external URL at the [time of installation](https://docs.gitlab.com/omnibus/settings/configuration.html#specifying-the-external-url-at-the-time-of-installation). |
| `EXTERNAL_VALIDATION_SERVICE_TIMEOUT` | integer | Timeout, in seconds, for an [external CI/CD pipeline validation service](external_pipeline_validation.md). Default is `5`. |
| `EXTERNAL_VALIDATION_SERVICE_URL` | string | URL to an [external CI/CD pipeline validation service](external_pipeline_validation.md). |
| `EXTERNAL_VALIDATION_SERVICE_TOKEN` | string | The `X-Gitlab-Token` for authentication with an [external CI/CD pipeline validation service](external_pipeline_validation.md). |
| `GITLAB_MARKUP_TIMEOUT` | string | Timeout, in seconds, for `rest2html` and `pod2html` commands executed by the [`gitlab-markup` gem](https://gitlab.com/gitlab-org/gitlab-markup/). Default is `10`. |