Request Flow

Overview

Request Flow is Clever Cloud’s automatic middleware chaining mechanism. It configures reverse proxies and services between the public port (8080) and your application, managing port allocation automatically. There is no need to manually configure listening ports for each service.

Request Flow is available in the following runtimes:

• FrankenPHP
• Linux
• Python with uv
• Static
• V (Vlang)

Supported services

Automatic detection

When no CC_REQUEST_FLOW is set, Clever Cloud detects and activates services automatically:

• If a clevercloud/varnish.vcl file exists (or CC_VARNISH_FILE is set), Varnish is activated
• If CC_REDIRECTIONIO_PROJECT_KEY is set, Redirection.io is activated

Both can be active simultaneously. Default order: Varnish first, then Redirection.io.

Port management

Request Flow allocates ports in a chain from port 8080 (public) down to the application:

• With no middleware: your application listens directly on port 8080
• With one middleware: the middleware listens on 8080, forwards to your application on port 9000
• With two middleware: first listens on 8080, forwards to second on 8081, which forwards to the application on 9000

Your application must listen on port 8080 when no middleware is active, or on port 9000 when at least one middleware is configured.

Explicit configuration with CC_REQUEST_FLOW

To control the order or selection of middleware, set CC_REQUEST_FLOW to a comma-separated list of services:

CC_REQUEST_FLOW="redirectionio,varnish"

This inverts the default order: Redirection.io listens on 8080, forwards to Varnish on 8081, which forwards to the application on 9000.

Disable Request Flow

To disable Request Flow entirely and have your application listen directly on port 8080:

CC_REQUEST_FLOW="disable"

Custom middleware

To insert a custom reverse proxy in the chain, add custom to CC_REQUEST_FLOW and define the command with CC_REQUEST_FLOW_CUSTOM. The deployment process replaces @@LISTEN_PORT@@ and @@FORWARD_PORT@@ placeholders with the actual allocated ports:

CC_REQUEST_FLOW="redirectionio,custom,varnish"
CC_REQUEST_FLOW_CUSTOM="./my-proxy --listen @@LISTEN_PORT@@ --forward @@FORWARD_PORT@@"

In this example:

• Redirection.io listens on 8080, forwards to custom middleware on 8081
• Custom middleware listens on 8081, forwards to Varnish on 8082
• Varnish listens on 8082, forwards to the application on 9000

Environment variables reference

• Learn more about Varnish on Clever Cloud
• Learn more about Redirection.io
• Learn more about Network Groups