Environment Variables & Metadata

GameFlow automatically injects a set of environment variables and metadata into every game server at runtime. These are available without any additional configuration from the developer.

Environment Variables

These values are injected as standard environment variables into the game server container. They are available via process.env (JS/TS),Environment.GetEnvironmentVariable (C#/Unity), or equivalent in your runtime or engine.

Variable	Type	Description	Example
GAMEFLOW_REGION	string	The region where the game server is running.	us-east
GAMEFLOW_DEFAULT_PORT	string	The primary/default port assigned to the game server container.	7777
GAMEFLOW_{NAME}_PORT	string	One env var per additional port configured on the fleet, where {NAME} is the port label uppercased with spaces replaced by underscores.	9090

Usage Examples

C# / Unity:

var region = Environment.GetEnvironmentVariable("GAMEFLOW_REGION");
var defaultPort = Environment.GetEnvironmentVariable("GAMEFLOW_DEFAULT_PORT");

// Server running in us-east on port 7777
Debug.Log($"Server running in {region} on port {defaultPort}");

var voiceChatPort = Environment.GetEnvironmentVariable("GAMEFLOW_VOICE_CHAT_PORT");

// Voice chat on port 9090
Debug.Log($"Voice chat on port {voiceChatPort}");

JS/TS:

const defaultPort = process.env.GAMEFLOW_DEFAULT_PORT;
const region = process.env.GAMEFLOW_REGION;

// Server running in us-east on port 7777
console.log(`Server running in ${region} on port ${defaultPort}`); 

const voiceChatPort = process.env.GAMEFLOW_VOICE_CHAT_PORT;

// Voice chat on port 9090
console.log(`Voice chat on port ${voiceChatPort}`);

Additional Ports

When you configure additional ports on your fleet, GameFlow generates an environment variable for each one using the naming convention GAMEFLOW_{NAME}_PORT, where {NAME} is the port label uppercased with spaces replaced by underscores.

For example, a fleet configured with a default port and two additional ports labeled "voice chat" and "debug" would receive:

Environment Variable	Value
GAMEFLOW_DEFAULT_PORT	7777
GAMEFLOW_VOICE_CHAT_PORT	9090
GAMEFLOW_DEBUG_PORT	9091

Metadata

Per-session metadata such as the launch payload is delivered to your server and read using the GameFlow Game Server SDK.

Annotation	Type	Description	Example
GAMEFLOW_PAYLOAD	string (JSON)	Optional JSON string with player or session data, passed at server creation or allocation time.	{"players": ["p1", "p2"]}

Reading the Payload

Retrieve the launch payload with the SDK's payload() call. It returns an opaque string (whatever you passed at allocation), so parse it however you produced it. To react when a server is reassigned to a new match, subscribe with onPayloadChange; see the SDK Quickstart.

C# / Unity:

var payload = await gf.Payload(); // string (null when none)

if (!string.IsNullOrEmpty(payload)) {
    var data = JsonConvert.DeserializeObject(payload);
    Debug.Log(data); // {"players": ["p1", "p2"]}
}

JS/TS

const payload = await gf.payload(); // string | undefined

if (payload) {
  const data = JSON.parse(payload);
  console.log(data); // {"players": ["p1", "p2"]}
}

Godot / GDScript:

var res := await gf.payload()

if res.value != null:
    var data = JSON.parse_string(res.value)
    print(data)  # {"players": ["p1", "p2"]}

How Are These Different from Custom Environment Variables?

When creating a game in GameFlow, you can define custom environment variables that are baked into the container spec. These are static values used for configuration that doesn't change between sessions (e.g., LOG_LEVEL).

GameFlow-provided values are different:

• Automatically injected by the platform, no manual configuration needed.
• GAMEFLOW_REGION, GAMEFLOW_DEFAULT_PORT, and GAMEFLOW_{NAME}_PORT are environment variables that reflect the runtime context of each server instance.
• GAMEFLOW_PAYLOAD is not an environment variable; it carries dynamic, per-session data passed at allocation or server creation time, and is read with the GameFlow Game Server SDK's payload() call.

This separation allows developers to keep static configuration in the image while still receiving dynamic, per-instance and per-session data at runtime.