---
title: "Build Docker Image Concurrently with BuildKit"
date: 2021-12-06T23:09:47.000Z
author: Z.SHINCHVEN
tags: [Docker, docker buildKit, docker buildx, docker-compose]
canonical: https://atlassc.net/2021/12/07/build-docker-image-concurrently-with-buildkit
---
## Docker Pipeline Taking Too Much Time to Finish?

I used to build docker image step by step, that's before I found out about docker's [BuildKit](https://docs.docker.com/develop/develop-images/build_enhancements/). With the `BuildKit`, the building time was reduced by 60% (in my case), I mean that's crazy.

## How Does the Concurrent Building Process Work?

Just split your Dockerfile into stages, the docker BuildKit will analyse all steps' dependency of each other, and run multiple stages parallel. If a step does not depend on any other step, it will go straight forward. If a step depends on any other step, it will wait for its prerequisite to finish.

Here's a piece of Dockerfile from my project:

```Dockerfile
FROM shinchven/node:16-build

WORKDIR /root/build/web
COPY web /root/build/web
RUN npm i
RUN npm run build

FROM shinchven/node:16-build

WORKDIR /root/build/app
COPY app /root/build/app
RUN npm i -g shx
RUN npm install
RUN npm run compile

FROM shinchven/node:16-deployment

WORKDIR /usr/src/app

COPY --from=1 /root/build/app /usr/src/app
COPY --from=0 /root/build/web/dist /usr/src/app/public/web

ENV NODE_ENV=production

EXPOSE 3030

CMD ["pm2-docker","ecosystem.config.js"]
```

All stages started at the same time, while step 3 of stage-2 waited for stage-0 and stage-1 to finish, because the `--from=1` and `--from=0` flag of  `COPY` command tells the step to wait for the stage-0 and stage-1 to finish. Thus, I saved a lot of time.

## Use BuildKit

There are a few ways to use BuildKit:

```bash
# Enable BuildKit for docker and docker-compose
DOCKER_BUILDKIT=1 docker build .
DOCKER_BUILDKIT=1 docker-compose build
# Use [buildx](https://docs.docker.com/buildx/working-with-buildx/) command
docker buildx build .
```

Please see official [documentation](https://docs.docker.com/develop/develop-images/build_enhancements/#to-enable-buildkit-builds) for more details.