Go app (in docker container) not reflecting changes on page?-CodePudding

I'm new to Go, but having an annoying issue where changes in the code are not reflected on the page, unless I do another --build when I bring up the container. Is this normal? I'm running`Windows 10, Go 1.19, AMD, Docker Desktop/Compose.

If I change "Hello, World!" to some other string, CTRL C the running app, and then run docker-compose up, the changes are NOT reflected on the page, even after clearing browser cache and using an incognito window. HOWEVER, if I run docker-compose up --build, the changes WILL be reflected.

Reminder I'm new to Go, but is this normal behaviour? Do I have to re-build the project in docker-compose each time to see the changes? Or do you see anything "off" in my code? I'm following a few year old Udemy course, so of course every step there's a new "thing" to troubleshoot as it doesn't work as shown eye roll

They suggest using Air for hot-reloading, which I'm also having an issue with as IT'S not working either, however I've opened a GitHub issue for that.

Here is the code from the various files:

main.go

package main

import (
    "ambassador/src/database"

    "github.com/gofiber/fiber/v2"
)

func main() {

    // Connect to the database
    database.Connect()

    // Migrate tables in the database
    database.AutoMigrate()

    // Create a new fiber app, which is based on Express.js
    app := fiber.New()

    app.Get("/", func(c *fiber.Ctx) error {
        return c.SendString("Hello, World!")
    })

    app.Listen(":3000")
}

Dockerfile

FROM golang:1.19

WORKDIR /app
COPY go.mod .
COPY go.sum .
RUN go mod download

COPY . .

# Use air for live go hot-reloading
# This one doesn't work, use go install instead
# RUN curl -sSfL https://raw.githubusercontent.com/cosmtrek/air/master/install.sh | sh -s -- -b $(go env GOPATH)/bin

# Air does not work for me. Opening github issue. Skip for now
# RUN go install github.com/cosmtrek/air@latest
# CMD ["air"]

CMD ["go", "run", "main.go"]

docker-compose.yaml

version: '3.9'
services:
    backend:
        build: .
        ports:
            - 8000:3000
        # volumes:
        #   - .:/app
        depends_on:
            - db

    db:
        image: mysql:5.7.22
        restart: always
        environment:
            MYSQL_DATABASE: ambassador
            MYSQL_USER: root
            MYSQL_PASSWORD: root
            MYSQL_ROOT_PASSWORD: root
        volumes:
            - .dbdata:/var/lib/mysql
        ports:
            - 33066:3306

src > database > db.go

package database

import (
    "ambassador/src/models"

    "gorm.io/driver/mysql"
    "gorm.io/gorm"
)

var DB *gorm.DB

func Connect() {
    var err error
    DB, err = gorm.Open(mysql.Open("root:root@tcp(db:3306)/ambassador"), &gorm.Config{})

    if err != nil {
        panic("Could not connect with the database!")
    }
}

func AutoMigrate() {
    DB.AutoMigrate(models.User{})
}

src > models > user.go

package models

type User struct {
    Id           uint
    FirstName    string
    LastName     string
    Email        string
    Password     string
    IsAmbassador bool
}

go.mod

module ambassador

go 1.19

require github.com/gofiber/fiber/v2 v2.36.0

require (
    github.com/andybalholm/brotli v1.0.4 // indirect
    github.com/go-sql-driver/mysql v1.6.0 // indirect
    github.com/jinzhu/inflection v1.0.0 // indirect
    github.com/jinzhu/now v1.1.5 // indirect
    github.com/klauspost/compress v1.15.0 // indirect
    github.com/valyala/bytebufferpool v1.0.0 // indirect
    github.com/valyala/fasthttp v1.38.0 // indirect
    github.com/valyala/tcplisten v1.0.0 // indirect
    golang.org/x/sys v0.0.0-20220227234510-4e6760a101f9 // indirect
    gorm.io/driver/mysql v1.3.5 // indirect
    gorm.io/gorm v1.23.8 // indirect
)

The same code is included in this screenshot of my IDE.

CodePudding user response：

Go isn’t a script language and needs in rebuild and restart application to apply changes

You can use Golang fresh for rebuild and restart your app

https://github.com/gravityblast/fresh

Add this to your Dockerfile

RUN go install github.com/pilu/fresh@latest
...
CMD [ "fresh" ]

CodePudding user response：

You are not mounting any files into your container, only copying them once on image build. This is why you are not seeing anychanges unless you build, or copy new files into the container.

You've already commented out a volume from your docker-compose.yaml, but if you uncomment those lines you should see that changes are reflected without rebuilding.