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This guide assumes you already have Docker Desktop installed.
Docker is a platform for packaging and running an application as a lightweight, portable container that encapsulates all the necessary dependencies.
To containerize the application, define a Dockerfile. It lists the instructions to initialize the container, copy your local project files into it, install dependencies, and start the application.
Dockerfile
# use the official Bun image
# see all versions at https://hub.docker.com/r/oven/bun/tags
FROM oven/bun:1 AS base
WORKDIR /usr/src/app

# install dependencies into temp directory
# this will cache them and speed up future builds
FROM base AS install
RUN mkdir -p /temp/dev
COPY package.json bun.lock /temp/dev/
RUN cd /temp/dev && bun install --frozen-lockfile

# install with --production (exclude devDependencies)
RUN mkdir -p /temp/prod
COPY package.json bun.lock /temp/prod/
RUN cd /temp/prod && bun install --frozen-lockfile --production

# copy node_modules from temp directory
# then copy all (non-ignored) project files into the image
FROM base AS prerelease
COPY --from=install /temp/dev/node_modules node_modules
COPY . .

# [optional] tests & build
ENV NODE_ENV=production
RUN bun test
RUN bun run build

# copy production dependencies and source code into final image
FROM base AS release
COPY --from=install /temp/prod/node_modules node_modules
COPY --from=prerelease /usr/src/app/index.ts .
COPY --from=prerelease /usr/src/app/package.json .

# run the app
USER bun
EXPOSE 3000/tcp
ENTRYPOINT [ "bun", "run", "index.ts" ]
Next, add a .dockerignore file. It uses the same syntax as .gitignore and lists the files and directories to exclude from every stage of the Docker build. For example:
.dockerignore
node_modules
Dockerfile*
docker-compose*
.dockerignore
.git
.gitignore
README.md
LICENSE
.vscode
Makefile
helm-charts
.env
.editorconfig
.idea
coverage*
Run docker build to convert this Dockerfile into a Docker image, a self-contained template containing all the dependencies and configuration required to run the application. The -t flag names the image, and --pull tells Docker to download the latest version of the base image (oven/bun). The initial build takes longer, since Docker downloads all the base images and dependencies.
terminal
docker build --pull -t bun-hello-world .

[+] Building 0.9s (21/21) FINISHED
 => [internal] load build definition from Dockerfile                                                                                     0.0s
 => => transferring dockerfile: 37B                                                                                                      0.0s
 => [internal] load .dockerignore                                                                                                        0.0s
 => => transferring context: 35B                                                                                                         0.0s
 => [internal] load metadata for docker.io/oven/bun:1                                                                                    0.8s
 => [auth] oven/bun:pull token for registry-1.docker.io                                                                                  0.0s
 => [base 1/2] FROM docker.io/oven/bun:1@sha256:373265748d3cd3624cb3f3ee6004f45b1fc3edbd07a622aeeec17566d2756997                         0.0s
 => [internal] load build context                                                                                                        0.0s
 => => transferring context: 155B                                                                                                        0.0s
 # ...lots of commands...
 => exporting to image                                                                                                                   0.0s
 => => exporting layers                                                                                                                  0.0s
 => => writing image sha256:360663f7fdcd6f11e8e94761d5592e2e4dfc8d167f034f15cd5a863d5dc093c4                                             0.0s
 => => naming to docker.io/library/bun-hello-world                                                                                       0.0s
Now start a running container from the bun-hello-world image with docker run. The -d flag runs it in detached mode, and -p 3000:3000 maps the container’s port 3000 to port 3000 on your machine. The run command prints the container ID.
terminal
docker run -d -p 3000:3000 bun-hello-world

7f03e212a15ede8644379bce11a13589f563d3909a9640446c5bbefce993678d
The container is now running in the background. Visit localhost:3000. You should see a Hello, World! message.
To stop the container, run docker stop <container-id>.
terminal
docker stop 7f03e212a15ede8644379bce11a13589f563d3909a9640446c5bbefce993678d
If you can’t find the container ID, docker ps lists all running containers.
terminal
docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
7f03e212a15e        bun-hello-world     "bun run index.ts"       2 minutes ago       Up 2 minutes        0.0.0.0:3000->3000/tcp   flamboyant_cerf
See the Docker documentation for more advanced usage.