All Coder features are supported in offline / behind firewalls / in air-gapped environments. However, some changes to your configuration are necessary.

| | Public deployments | Offline deployments |

| ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

| Terraform binary | By default, Coder downloads Terraform binary from [releases.hashicorp.com](https://releases.hashicorp.com) | Terraform binary must be included in `PATH` for the VM or container image. [Supported versions](https://github.com/coder/coder/blob/main/provisioner/terraform/install.go#L23-L24) |

| Terraform registry | Coder templates will attempt to download providers from [registry.terraform.io](https://registry.terraform.io) or [custom source addresses](https://developer.hashicorp.com/terraform/language/providers/requirements#source-addresses) specified in each template | [Custom source addresses](https://developer.hashicorp.com/terraform/language/providers/requirements#source-addresses) can be specified in each Coder template, or a custom registry/mirror can be used. More details below |

| STUN | By default, Coder uses Google's public STUN server for direct workspace connections | STUN can be safely [disabled](../cli/coder_server#--derp-server-stun-addresses), users can still connect via [relayed connections](../networking.md#-geo-distribution). Alternatively, you can set a [custom DERP server](../cli/coder_server#--derp-server-stun-addresses) |

| DERP | By default, Coder's built-in DERP relay can be used, or [Tailscale's public relays](../networking.md#relayed-connections). | By default, Coder's built-in DERP relay can be used, or [custom relays](../networking.md#custom-relays). |

| PostgreSQL | If no [PostgreSQL connection URL](../cli/coder_server#--postgres-url) is specified, Coder will download Postgres from [repo1.maven.org](https://repo1.maven.org). | An external database is required, you must specified a [PostgreSQL connection URL](../cli/coder_server#--postgres-url) |

| Telemetry | Telemetry is on by default, and [can be disabled](../cli/coder_server#--telemetry) | Telemetry [can be disabled](../cli/coder_server#--telemetry) |

The following instructions walk you through how to build a custom Coder server image for Docker or Kubernetes

environment:

CODER_TELEMETRY_ENABLE: false # disable telemetry

CODER_DERP_SERVER_STUN_ADDRESSES: "" # only use relayed connections

env:

# Disable telemetry

- name: "CODER_TELEMETRY_ENABLE"

value: "false"

# Only use relayed connections

- name: "CODER_DERP_SERVER_STUN_ADDRESSES"

value: ""

If a direct connection is not available (e.g. client or server is behind NAT), Coder

will use a relayed connection. By default, [Coder uses Google's public STUN server](./cli/coder_server#--derp-server-stun-addresses), but

this can be disabled or changed for [offline deployments](./install/offline.md).

By default, your Coder server also runs a built-in DERP relay which can be used for both public and [offline deployments](./install/offline.md).

However, Tailscale has graciously allowed us to use

[their global DERP relays](https://tailscale.com/kb/1118/custom-derp-servers/#what-are-derp-servers). You can launch `coder server` with Tailscale's DERPs like so:

If you want lower latency than what Tailscale offers or want additional DERP relays for offline deployments, you may run custom DERP servers. Refer to [Tailscale's documentation](https://tailscale.com/kb/1118/custom-derp-servers/#why-run-your-own-derp-server)