Using Docker on Synology DSM with an HTTP Proxy

This article describes a simple and reliable configuration to allow Docker on Synology DSM to pull images through an HTTP proxy.

Environment

• Synology NAS (DSM 7.x)
• Docker package (Container Manager / Docker)
• HTTP Proxy reachable from the NAS

1. Configure Docker to Use an HTTP Proxy

On Synology DSM, Docker runs as a systemd service:

pkg-Docker-dockerd.service

(or pkg-ContainerManager-dockerd.service on newer DSM versions using Container Manager)

To configure Docker to use an HTTP proxy, create a systemd drop-in file.

Create the configuration directory

# For Docker package
sudo mkdir -p /etc/systemd/system/pkg-Docker-dockerd.service.d

# For Container Manager package
sudo mkdir -p /etc/systemd/system/pkg-ContainerManager-dockerd.service.d

Create the proxy configuration file

# Docker package
sudo vi /etc/systemd/system/pkg-Docker-dockerd.service.d/http-proxy.conf

# Container Manager package
sudo vi /etc/systemd/system/pkg-ContainerManager-dockerd.service.d/http-proxy.conf

Add the following content:

[Service]
Environment="HTTP_PROXY=http://<PROXY_HOST>:<PROXY_PORT>"
Environment="HTTPS_PROXY=http://<PROXY_HOST>:<PROXY_PORT>"
Environment="NO_PROXY=localhost,127.0.0.1,::1,192.168.0.0/16,10.0.0.0/8,172.16.0.0/12"

Replace <PROXY_HOST> and <PROXY_PORT> with the address of your HTTP proxy.

2. Apply the Configuration

Reload systemd and restart Docker:

sudo systemctl daemon-reload

# Docker package
sudo systemctl restart pkg-Docker-dockerd.service

# Container Manager package
sudo systemctl restart pkg-ContainerManager-dockerd.service

3. Pull Docker Images

After restarting Docker, images can be pulled normally:

docker pull alpine:latest