Dockerfile

# https://docs.docker.com/samples/library/node/
ARG NODE_VERSION=16

# Build container
FROM node:${NODE_VERSION}-alpine AS build
ARG DUMB_INIT_VERSION

WORKDIR /home/node

ADD . /home/node

RUN apk add git

RUN yarn install

RUN yarn build && yarn cache clean

# Runtime container
FROM node:${NODE_VERSION}-alpine

WORKDIR /home/node

COPY --from=build /home/node /home/node

EXPOSE 8080
CMD ["yarn", "run", "serve"]

fly.toml

# fly.toml file generated for fid-express on 2022-07-13T13:06:07-05:00

app = "fid-express"
kill_signal = "SIGINT"
kill_timeout = 5
processes = []

[env]
  PORT=8080

[experimental]
  allowed_public_ports = []
  auto_rollback = true

[[services]]
  http_checks = []
  internal_port = 8080
  processes = ["app"]
  protocol = "tcp"
  script_checks = []
  [services.concurrency]
    hard_limit = 25
    soft_limit = 20
    type = "connections"

  [[services.ports]]
    force_https = true
    handlers = ["http"]
    port = 80

  [[services.ports]]
    handlers = ["tls", "http"]
    port = 443

  [[services.tcp_checks]]
    grace_period = "1s"
    interval = "15s"
    restart_limit = 0
    timeout = "2s"

index.js

const express = require('express')
const app = express()

require('dotenv').config();

app.get('/admin', (req, res) => {
  res.send('Hello Admin!')
})

app.listen(process.env.PORT || 3000)

package.json

{
  "name": "fid-express",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "serve": "NODE_ENV=production node index.js",
    "build": "echo \"building\""
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "dotenv": "^16.0.1",
    "express": "^4.18.1"
  }
}