Configure proxy for Docker

For Docker Engine

Reference: https://docs.docker.com/engine/daemon/proxy/#systemd-unit-file

Create a systemd drop-in directory for the docker service:

sudo mkdir -p /etc/systemd/system/docker.service.d

Create and edit a configuration file for proxy:

sudo nano /etc/systemd/system/docker.service.d/http-proxy.conf

With the following content:

[Service]
Environment="HTTP_PROXY=http://proxy.example.com:3128"
Environment="HTTPS_PROXY=http://proxy.example.com:3128"
Environment="NO_PROXY=localhost,127.0.0.0/8,::1"

Flush changes:

sudo systemctl daemon-reload

Restart Docker:

sudo systemctl restart docker

Verify that the configuration is applied:

sudo systemctl show --property=Environment docker

The configuration should appear in the output. Example:

Environment=HTTP_PROXY=http://proxy.example.com:3128 HTTPS_PROXY=http://proxy.example.com:3128 NO_PROXY=localhost,127.0.0.0/8,::1

For a Docker container

Reference: https://forums.docker.com/t/how-to-reach-localhost-on-host-from-docker-container/113321

Accessing a proxy server running on the host machine

In the docker-compose file:

services:
  container:
    ...
    environment:
      ...
      HTTP_PROXY: http://proxy.example.com:3128
      HTTPS_PROXY: http://proxy.example.com:3128
      NO_PROXY: "localhost,127.0.0.0/8,::1"
    extra_hosts:
      - "host.docker.internal:host-gateway"
...

📝 Note
Firewall rules may apply to the traffic between Docker’s virtual Ethernet adapter and the host machine’s Ethernet adapter. It might be a good idea to check the firewall configurations.

Restart the stack:

docker compose up -d

Accessing a proxy server elsewhere

The extra_hosts field is no longer needed. Simply configure the environment. Example:

services:
  container:
    ...
    environment:
      ...
      HTTP_PROXY: http://host.docker.internal:3128
      HTTPS_PROXY: http://host.docker.internal:3128
      NO_PROXY: "localhost,127.0.0.0/8,::1"
...