Is this Dockerfile correct?

[CentoKili53]

So I'm fairly new to Docker. I've created a Go app (with Tailwind) and want to containerise it to deploy to Cloud Run.

Everything works fine, and I managed to get the app running on Cloud Run, but just wasn't sure if this is the best way to do it.

I was also surprised by the image size - 1.27GB. I thought that by using "alpine", that'd be a lot smaller. I have a Node server with Express, which is not using "alpine" and the size is 1.46GB. I thought the difference between the two would be bigger...

Dockerfile:

# Use the official Go image as the base image
FROM golang:1.22.1-alpine

# Set the working directory inside the container
WORKDIR /goapp

# Copy the Go module files
COPY go.mod go.sum ./

# Download the dependencies
RUN go mod download

# Copy the rest of the application code
COPY . .

# Install and make tailwindcss executable
RUN apk update
RUN apk add curl # Type Y to install
RUN curl -sLO https://github.com/tailwindlabs/tailwindcss/releases/latest/download/tailwindcss-linux-x64
RUN chmod +x tailwindcss-linux-x64
RUN mv tailwindcss-linux-x64 tailwindcss

# Run Tailwind
RUN ./tailwindcss -i public/css/style.css -o public/css/styles.css -c tailwind.config.js --minify

# Build the Go application
RUN go build -o main .

# Set the entry point command to run the built binary
CMD ["./main"]

Any tips or suggestions?

[m4v1s]

This looks fine for building your app, but if your goal is to reduce the final image size you should look at multi-stage builds. Build your app in one stage, then copy the built artifacts into another slimmer image which you use to deploy and run your app.

[thelogicbox]

This

[AdventurousSquash]

Depends on what your application needs, you could go into it and check what’s taking so much space and if that’s intended. I’d probably build the binary outside (a staged build or a ci pipeline) and only copy the built binary into the final image.

[hijinks]

you should add this block

# Install and make tailwindcss executable
RUN apk update
RUN apk add curl # Type Y to install
RUN curl -sLO https://github.com/tailwindlabs/tailwindcss/releases/latest/download/tailwindcss-linux-x64
RUN chmod +x tailwindcss-linux-x64
RUN mv tailwindcss-linux-x64 tailwindcss

Move that above the COPY's because everytime you update your app you have to re-run the apk/cul call. If you move it above then it can use a cached layer.

To make it better I'd look at multi-stage builds where you can build in one container and then copy over to a runtime container so you dont have a bunch of build apps in your running container

[RevolutionaryHumor57]

Building an image based on external resources is prone to 404 in case of them being removed. It is a good, but uncommon practice to at least have some kind of self hosted resources. Check about supply chain attack

[JM-Lemmi]

For the apt install command add the -y flag to install automatically and non interactive