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Use Caddy to reverse proxy with Fly.io

Use Caddy to reverse proxy with Fly.io

Introduction

To deploy several services in one fly.io app, using Caddy as reverse proxy.

Project directory:

├── chat-avatar (Service 1)
├── psn-steam-api (Service 2)
├── Caddyfile
├── Dockerfile
└── fly.toml

Steps

Caddyfile

:7070 {
    # psn-steam-api
    handle /psn-steam-api/* {
        # remove /psn-steam-api from the request
        uri strip_prefix /psn-steam-api
        reverse_proxy localhost:7071
    }

    # chat-avatar
    handle /chat-avatar/* {
        uri strip_prefix /chat-avatar
        reverse_proxy localhost:7072
    }

    # homepage
    handle / {
        respond "NO CONTENT" 200
    }

    log {
        output stdout
    }
}

Dockerfile

FROM golang:1.22-alpine AS builder

# psn-steam-api
WORKDIR /app/psn-steam-api
COPY ./psn-steam-api .
RUN go mod download
RUN go build -o main ./cmd/main.go

# chat-avatar
WORKDIR /app/chat-avatar
COPY ./chat-avatar .
RUN go mod download
RUN go build -o main ./cmd/main.go

# caddy
FROM caddy:2.7-alpine

COPY ./Caddyfile /etc/caddy/Caddyfile

COPY --from=builder /app/psn-steam-api/main /usr/local/bin/psn-steam-api
COPY --from=builder /app/chat-avatar/main /usr/local/bin/chat-avatar

# start script
RUN printf '#!/bin/sh\npsn-steam-api &\nchat-avatar &\ncaddy run --config /etc/caddy/Caddyfile\n' > /usr/local/bin/start.sh

RUN chmod +x /usr/local/bin/start.sh
RUN chmod +x /usr/local/bin/psn-steam-api
RUN chmod +x /usr/local/bin/chat-avatar

EXPOSE 7070

CMD ["/usr/local/bin/start.sh"]

fly.toml

app = 'app-name'
primary_region = 'nrt'

[build]

[http_service]
  internal_port = 7070
  force_https = true
  auto_stop_machines = 'stop'
  auto_start_machines = true
  min_machines_running = 1
  processes = ['app']

[[vm]]
  memory = '512mb'
  cpu_kind = 'shared'
  cpus = 1

Deploy

fly deploy