Quick answer: configure Docker proxy access at the daemon level, not only in your shell. Set HTTP_PROXY and HTTPS_PROXY, reload the Docker service configuration, and restart Docker so image pulls and container operations use the proxy.
When Docker Needs Proxy Configuration
Docker often needs proxy configuration in corporate networks, restricted lab environments, or machines that can only reach the internet through an HTTP proxy.
If Docker is not configured correctly, you may see failures when pulling images, building containers, or reaching package repositories during a build.
Ubuntu
Set Docker to Use an HTTP Proxy
Older Ubuntu setups may use /etc/default/docker:
sudo /etc/default/docker
export http_proxy="http://127.0.0.1:3128/"
export https_proxy="http://127.0.0.1:3128/"
export HTTP_PROXY="http://127.0.0.1:3128/"
export HTTPS_PROXY="http://127.0.0.1:3128/"
Load Configuration and Restart Docker
sudo service docker restart
CentOS
Set Docker to Use an HTTP Proxy
For systemd-based systems, use a Docker service drop-in:
sudo mkdir -p /etc/systemd/system/docker.service.d
echo '
[Service]
Environment="HTTP_PROXY=http://proxy.foo.bar.com:80/"
' | sudo tee /etc/systemd/system/docker.service.d/http-proxy.conf
Load Configuration and Restart Docker
sudo systemctl daemon-reload
sudo systemctl restart docker
Verify Docker Is Using the Proxy
After restarting Docker, test image pulls:
docker pull hello-world
You can also inspect the Docker service environment:
systemctl show --property=Environment docker
If the proxy is configured correctly, Docker should be able to pull images without manual shell-only proxy exports.
Add NO_PROXY for Internal Hosts
If Docker also needs to reach internal registries or private services directly, configure NO_PROXY.
Example:
Environment="HTTP_PROXY=http://proxy.example.com:80/"
Environment="HTTPS_PROXY=http://proxy.example.com:80/"
Environment="NO_PROXY=localhost,127.0.0.1,.example.internal"
Without NO_PROXY, Docker may route internal traffic through the proxy unnecessarily.
Related Docker Setup
If the next problem is needing sudo for every Docker command, read How to Run Docker Commands as a Non-Root User.
Final Check
The clean state is:
- Docker proxy settings are configured at the daemon level
- Docker has been restarted after the change
docker pull hello-worldworks- internal hosts are covered by
NO_PROXYwhere needed - proxy values are not hard-coded into Dockerfiles unless the build specifically requires it