Hot reload by air is not working on my app

I want to use hot reload in my golang app. I use air package.

But when I modify my main.go, the api response is not changed.

↓ my app folders.

my-app
   |--- app
   |      |--- .air.toml
   |      |--- Dockerfile
   |      |--- go.mod
   |      |--- go.sum
   |      |--- main.go
   |
   |--- docker-compose.yml

↓ Dockerfile

FROM golang:1.16

ENV GOPATH /go
ENV GO111MODULE on

COPY go.mod /var/www/html/go.mod
COPY go.sum /var/www/html/go.sum
WORKDIR /var/www/html/
RUN go mod download

RUN go mod tidy && \
    go install github.com/cosmtrek/air@v1.27.3

COPY . /var/www/html/

CMD ["air", "-c", ".air.toml"]

↓ docker-compose.yml

version: '3'
services:
  app:
    build: ./app
    tty: true
    volumes:
      - ./app:/var/www/html
    depends_on:
      - mysql
    ports:
      - "3000:3000"
    command: "air"

↓ main.go

package main

import (
    "net/http"

    "github.com/gin-gonic/gin"
)

func main() {
    engine := gin.Default()
    engine.GET("/", func(c *gin.Context) {
        c.JSON(http.StatusOK, gin.H{
            "message": "hello world",
        })
    })
    engine.Run(":3000")
}

I created .air.toml by air init command in my app container.

And when I do command docker-compose up --build, I get ↓.

my console

What is wrong?