Using the Envoy Docker Image

Note

Envoy OCI images are built using Docker and have been extensively tested in large scale deployments running with Docker. Use of other container technologies such as Podman might function correctly but have not been extensively tested and are not expressly supported.

The following examples use the official Envoy OCI image.

These instructions are known to work for the x86_64 and arm64 architectures.

Running Envoy with `docker compose`

If you would like to use Envoy with docker compose you can overwrite the provided configuration file by using a volume.

version: '3'
services:
  envoy:
    image: envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6
    ports:
      - "10000:10000"
    volumes:
      - ./envoy.yaml:/etc/envoy/envoy.yaml

If you use this method, you will have to ensure that the envoy user can read the mounted file either by ensuring the correct permissions on the file, or making it world-readable, as described below.

Build and run an Envoy image with Docker

Create a simple Dockerfile to execute Envoy.

If you create a custom envoy.yaml you can create your own Docker image with it using the following Dockerfile recipe:

FROM envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6
COPY envoy.yaml /etc/envoy/envoy.yaml
RUN chmod go+r /etc/envoy/envoy.yaml

Build the Docker image using:

$ docker build -t envoy:v1 .

Assuming Envoy is configured to listen on ports 9901 and 10000, you can now start it in Docker with:

$ docker run -d --name envoy -p 9901:9901 -p 10000:10000 envoy:v1

or in Podman (unsupported) with:

$ podman run -d --name envoy -p 9901:9901 -p 10000:10000 envoy:v1

Root filesystem permissions for running Envoy in containers

The Envoy container image can be run with the container’s root filesystem mounted read-only. For example, using Docker and Podman, you can use the --read-only option of the run command.

With Kubernetes, this means setting podSpec.containers.securityContext.readOnlyFilesystem to true.

With Nomad, this means setting readonly_rootfs = true in the task’s config block when using the docker or podman driver.

Permissions for running Envoy in containers as a non-root user

By default, the Envoy OCI image will start as the root user but will switch to the envoy user created at build time, in the Docker ENTRYPOINT.

Alternatively, you can start the container specifying the Docker user.

In this case the container will not attempt to drop privileges, but you will still need to ensure that the user running inside the container has any required permissions, as described below.

Changing the `uid` and/or `gid` of the `envoy` user inside the container

The default uid and gid for the envoy user are 101.

The uid and gid of this user can be set at runtime using the ENVOY_UID and ENVOY_GID environment variables.

This can be done, for example, on the Docker command line:

$ docker run -d --name envoy -e ENVOY_UID=777 -e ENVOY_GID=777 envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6

This can be useful if you wish to restrict or provide access to unix sockets inside the container, or for controlling access to an Envoy socket from outside of the container.

To run the process inside the container as the root user you can set ENVOY_UID to 0, but doing so has the potential to weaken the security of your running container.

Logging permissions inside the Envoy container

The envoy image sends application logs to /dev/stdout and /dev/stderr by default, and these can be viewed in the container log.

If you send application, admin or access logs to a file output, the envoy user will require the necessary permissions to write to this file. This can be achieved by setting the ENVOY_UID and/or by making the file writeable by the envoy user.

For example, to mount a log folder from the host and make it writable, you can:

$ mkdir logs
$ chown 777 logs
$ docker run -d --name envoy -v $(pwd)/logs:/var/log -e ENVOY_UID=777 envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6

You can then configure envoy to log to files in /var/log

Configuration and binary file permissions inside the Envoy container

The envoy user also needs to have permission to access any required configuration files mounted into the container.

Any binary files specified in the configuration should also be executable by the envoy user.

If you are running in an environment with a strict umask setting, you may need to provide envoy with access by setting the ownership and/or permissions of the file.

One method of doing this without changing any file permissions is to start the container with the host user’s uid, for example:

$ docker run -d --name envoy -v $(pwd)/envoy.yaml:/etc/envoy/envoy.yaml -e ENVOY_UID=$(id -u) envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6

Listen only on ports > 1024 inside the Envoy container

Unix-based systems restrict opening well-known ports (ie. with a port number < 1024) to the root user.

If you need to listen on a well-known port you can use Docker to do so.

For example, to create an Envoy server listening on port 8000, with forwarding from port 80:

$ docker run -d --name envoy -p 80:8000 envoyproxy/envoy:dev-1fea93583e535ca058a5cc105327e26ff1e756a6