How to use this image

All examples in this guide use the public image. If you've mirrored the repository for your own use (for example, to your Docker Hub namespace), update your commands to reference the mirrored image instead of the public one.

For example:

• Public image: dhi.io/openspeedtest:<tag>
• Mirrored image: <your-namespace>/dhi-openspeedtest:<tag>

For the examples, you must first use docker login dhi.io to authenticate to the registry to pull the images.

OpenSpeedTest is a self-hosted HTML5 network speed test. Full project documentation is at https://openspeedtest.com⁠ and https://github.com/openspeedtest/Speed-Test⁠. This image replaces openspeedtest/latest.

Start an OpenSpeedTest image

The server listens on port 3000 for HTTP and port 3001 for HTTPS. There is no openspeedtest binary on PATH. nginx is the server, and the entrypoint is /docker-entrypoint.sh. A command you append to docker run is executed by that entrypoint.

Run the server

$ docker run -d --name openspeedtest \
  -p 3000:3000 \
  -p 3001:3001 \
  dhi.io/openspeedtest:<tag>

Open http://127.0.0.1:3000/⁠ for HTTP. The response is the speed-test page, and the body contains OpenSpeedTest:

$ curl -fsS http://127.0.0.1:3000/ | grep -F 'OpenSpeedTest'

HTTPS uses the certificate generated in the image. Browsers warn because that certificate is self-signed (CN=localhost). curl needs -k for the same reason:

$ curl -kfsS -o /dev/null -w '%{http_code}\n' https://127.0.0.1:3001/

The page downloads /downloading and posts the upload test to /upload:

$ curl -fsS -D - -o /dev/null http://127.0.0.1:3000/downloading | grep -i '^Content-Length:'
$ curl -fsS -o /dev/null -w '%{http_code}\n' -X POST http://127.0.0.1:3000/upload

GET /downloading returns Content-Length: 31457280. POST /upload returns 200.

Run nginx directly

$ docker run --rm dhi.io/openspeedtest:<tag> nginx -v

The command prints the bundled nginx version and exits.

Use your own TLS certificate

The image stores a self-signed certificate at /etc/ssl/nginx.crt and the key at /etc/ssl/nginx.key. Both files are mode 0444, and the certificate subject is CN=localhost. Replace them by mounting your own files at those two paths. The files must be readable by UID 65532. Mounting a directory over /etc/ssl hides the CA bundle, so mount the two files. Run the following commands from the directory that contains nginx.crt and nginx.key:

$ chmod 0444 nginx.crt nginx.key
$ docker run -d --name openspeedtest \
  -p 3000:3000 \
  -p 3001:3001 \
  -v "$PWD/nginx.crt:/etc/ssl/nginx.crt:ro" \
  -v "$PWD/nginx.key:/etc/ssl/nginx.key:ro" \
  dhi.io/openspeedtest:<tag>

If a container named openspeedtest is already running, remove it before this command. Confirm HTTPS still answers:

$ curl -kfsS -o /dev/null -w '%{http_code}\n' https://127.0.0.1:3001/

Document root

nginx serves files from /usr/share/openspeedtest. /usr/share/nginx/html is a symlink to that directory, so either path reaches the same files. The directory is writable by UID 65532.

Change the listen ports

Set CHANGE_CONTAINER_PORTS to True and set HTTP_PORT and HTTPS_PORT. The default command rewrites every 3000 and 3001 listener, including the IPv6 lines, then starts nginx. Publish the new container ports:

$ docker run -d --name openspeedtest \
  -e CHANGE_CONTAINER_PORTS=True \
  -e HTTP_PORT=3100 \
  -e HTTPS_PORT=3101 \
  -p 3100:3100 \
  -p 3101:3101 \
  dhi.io/openspeedtest:<tag>

$ curl -fsS -o /dev/null -w '%{http_code}\n' http://127.0.0.1:3100/

The command prints 200.

DOMAIN_NAME replaces YOURDOMAIN in the server name. ALLOW_ONLY is a semicolon-separated origin allow-list. SET_SERVER_NAME inserts a heading into INDEX_HTML. VERIFY_OWNERSHIP writes /usr/share/nginx/html/Verify.txt when that file is absent. CONFIG is the server file, /etc/nginx/conf.d/OpenSpeedTest-Server.conf.

Let's Encrypt issuance and cron are not included. ENABLE_LETSENCRYPT=True does not run certbot. Mount /etc/ssl/nginx.crt and /etc/ssl/nginx.key to use your own certificate. These directories exist and are writable by UID 65532:

• /var/log/letsencrypt
• /etc/letsencrypt
• /var/lib/letsencrypt

The runtime user is nginx (UID 65532). SET_USER is 65532. The working directory is /. Docker stops the container with SIGQUIT. The default command is /entrypoint.sh, which execs nginx -g 'daemon off;'.

Development image

Runtime tags run as UID 65532 and do not include bash. A development tag (the tag includes dev) runs as root and includes bash and a package manager (apt on Debian, apk on Alpine):

$ docker run --rm dhi.io/openspeedtest:<tag>-dev bash -c 'id -u'

The command prints 0.

Non-hardened images vs. Docker Hardened Images

Migration off openspeedtest/latest depends on the differences above:

• The entrypoint is /docker-entrypoint.sh. The default command is /entrypoint.sh, which applies the port, domain, and page switches and then execs nginx. A command you pass, such as nginx -v, replaces /entrypoint.sh.
• The document root is /usr/share/openspeedtest, and /usr/share/nginx/html links to it.
• TLS files are /etc/ssl/nginx.crt and /etc/ssl/nginx.key. Mount those two files.
• Container ports are 3000/tcp and 3001/tcp.
• The runtime user is UID 65532. Development tags run as root and include a shell.

Image variants

Docker Hardened Images come in different variants depending on their intended use. Image variants are identified by their tag.

• Runtime variants are designed to run your application in production. These images are intended to be used either directly or as the FROM image in the final stage of a multi-stage build. These images typically:

  • Run as a nonroot user
  • Do not include a shell or a package manager
  • Contain only the minimal set of libraries needed to run the app

• Build-time variants typically include dev in the tag name and are intended for use in the first stage of a multi-stage Dockerfile. These images typically:

  • Run as the root user
  • Include a shell and package manager
  • Are used to build or compile applications

• FIPS variants include fips in the variant name and tag. They come in both runtime and build-time variants. These variants use cryptographic modules that have been validated under FIPS 140, a U.S. government standard for secure cryptographic operations. For example, usage of MD5 fails in FIPS variants.

To view the image variants and get more information about them, select the Tags tab for this repository, and then select a tag.

Migrate to a Docker Hardened Image

To migrate your application to a Docker Hardened Image, you must update your Dockerfile. At minimum, you must update the base image in your existing Dockerfile to a Docker Hardened Image. This and a few other common changes are listed in the following table of migration notes.

The following steps outline the general migration process.

1. Find hardened images for your app.

   A hardened image may have several variants. Inspect the image tags and find the image variant that meets your needs.

2. Update the base image in your Dockerfile.

   Update the base image in your application's Dockerfile to the hardened image you found in the previous step. For framework images, this is typically going to be an image tagged as dev because it has the tools needed to install packages and dependencies.

3. For multi-stage Dockerfiles, update the runtime image in your Dockerfile.

   To ensure that your final image is as minimal as possible, you should use a multi-stage build. All stages in your Dockerfile should use a hardened image. While intermediary stages will typically use images tagged as dev, your final runtime stage should use a non-dev image variant.

4. Install additional packages

   Docker Hardened Images contain minimal packages in order to reduce the potential attack surface. You may need to install additional packages in your Dockerfile. Inspect the image variants to identify which packages are already installed.

   Only images tagged as dev typically have package managers. You should use a multi-stage Dockerfile to install the packages. Install the packages in the build stage that uses a dev image. Then, if needed, copy any necessary artifacts to the runtime stage that uses a non-dev image.

   For Alpine-based images, you can use apk to install packages. For Debian-based images, you can use apt-get to install packages.

Troubleshooting migration

The following are common issues that you may encounter during migration.

General debugging

The hardened images intended for runtime don't contain a shell nor any tools for debugging. The recommended method for debugging applications built with Docker Hardened Images is to use Docker Debug⁠ to attach to these containers. Docker Debug provides a shell, common debugging tools, and lets you install other tools in an ephemeral, writable layer that only exists during the debugging session.

Permissions

By default image variants intended for runtime, run as the nonroot user. Ensure that necessary files and directories are accessible to the nonroot user. You may need to copy files to different directories or change permissions so your application running as the nonroot user can access them.

Privileged ports

Non-dev hardened images run as a nonroot user by default. As a result, applications in these images can't bind to privileged ports (below 1024) when running in Kubernetes or in Docker Engine versions older than 20.10. To avoid issues, configure your application to listen on port 1025 or higher inside the container, even if you map it to a lower port on the host. For example, docker run -p 80:8080 my-image will work because the port inside the container is 8080, and docker run -p 80:81 my-image won't work because the port inside the container is 81.

No shell

By default, image variants intended for runtime don't contain a shell. Use dev images in build stages to run shell commands and then copy any necessary artifacts into the runtime stage. In addition, use Docker Debug to debug containers with no shell.

Entry point

Docker Hardened Images may have different entry points than images such as Docker Official Images. Use docker inspect to inspect entry points for Docker Hardened Images and update your Dockerfile if necessary.