Question 339120 in Docker Question posted in
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Golang hot reloading not working on docker with CompileDaemon in dev mode

I wanna make hot reloading for Golang on docker. I have created a Docker file looks like this:

# Go Version
FROM golang:latest

# Environment variables which CompileDaemon requires to run
ENV PROJECT_DIR=/app 
    GO111MODULE=on 
    CGO_ENABLED=0

# Basic setup of the container
RUN mkdir /app
COPY .. /app
WORKDIR /app

# Get CompileDaemon
RUN go get github.com/githubnemo/CompileDaemon
RUN go install github.com/githubnemo/CompileDaemon

# The build flag sets how to build after a change has been detected in the source code
# The command flag sets how to run the app after it has been built
ENTRYPOINT CompileDaemon -build="go build -o api" -command="./api"

and docker-compose.yml is:

version: '3.8'

name: live-reload-example

services:
  api:
    container_name: api
    build:
      context: .
      dockerfile: Dockerfile.dev
    ports:
      - 8501:8501
    volumes:
      - ./:/app

The container not reloading after the change

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I used air package instead of CompileDaemon and problem solved.

    FROM golang:latest

WORKDIR /go-app


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

# Install the air binary so we get live code-reloading when we save files
RUN curl -sSfL https://raw.githubusercontent.com/cosmtrek/air/master/install.sh | sh -s -- -b $(go env GOPATH)/bin


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

    in the first step, the .air.toml file does not exist, and you must create it with air init in the docker container.


  2. 0

    Container should not be reloaded. It runs CompilerDaemon. The daemon watches the mounted files and recompiles+restarts the app upon change.

    I’m not sure about COPY .. /app – what’s there in ..? I replaced it with COPY . /app and it worked with my duppy app.

    Just a few points:

    • No need to create /app, WORKDIR creates it automatically,
    • No need to copy your app to /app upon build since go build is invoked after start, and the contents of /app is overloaded by the mounted volume

    Here is my Dockerfile

    FROM golang:latest

# Environment variables which CompileDaemon requires to run
ENV PROJECT_DIR=/app 
    GO111MODULE=on 
    CGO_ENABLED=0

# Basic setup of the container
WORKDIR /app
# dummy module to make `go get` happy
RUN go mod init dummy

# Get CompileDaemon
RUN go get github.com/githubnemo/CompileDaemon
RUN go install github.com/githubnemo/CompileDaemon

# The build flag sets how to build after a change has been detected in the source code
# The command flag sets how to run the app after it has been built
ENTRYPOINT CompileDaemon -build="go build -o api" -command="./api"

    Here is the log of docker compose up:

    api  | 2024/02/10 17:52:24 Running build command!
api  | 2024/02/10 17:52:24 Build ok.
api  | 2024/02/10 17:52:24 Restarting the given command.
api  | 2024/02/10 17:52:24 stdout: Hello, world! Version 1
api  | 2024/02/10 17:52:35 Running build command!
api  | 2024/02/10 17:52:35 Build ok.
api  | 2024/02/10 17:52:35 Hard stopping the current process..
api  | 2024/02/10 17:52:35 Restarting the given command.
api  | 2024/02/10 17:52:35 stdout: Hello, world! Version 2

    As you see, when the container started, it built my application and launched it. The output of the application:

    api  | 2024/02/10 17:52:24 stdout: Hello, world! Version 1

    Then I edited the app and changed the line to Version 2:

    api  | 2024/02/10 17:52:35 Running build command!
api  | 2024/02/10 17:52:35 Build ok.
api  | 2024/02/10 17:52:35 Hard stopping the current process..
api  | 2024/02/10 17:52:35 Restarting the given command.
api  | 2024/02/10 17:52:35 stdout: Hello, world! Version 2

    IMHO, the container works as expected: it watches changes in sources and rebuilds and restarts the application.

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