docker can't access internet from within LXC Container

I have launched a Ubuntu 20.04 LXC container on RedHat 8.6 using the following command

lxc launch ubuntu:20.04 --storage default -c security.privileged=true -c boot.autostart=true --network lxdbr0

I installed docker in the container and configured my network proxy settings in /etc/systemd/system/docker.service.d/http-proxy.conf and then restarted the docker service.

[Service]
Environment="HTTP_PROXY=<proxy address redacted>"
Environment="HTTPS_PROXY=<proxy address redacted>"

I get a TLS handshake timeout error when I try to pull an image

root@still-katydid:~# docker pull nginx
Using default tag: latest
Error response from daemon: Get "https://registry-1.docker.io/v2/": net/http: TLS handshake timeout

Looking at /var/log/syslog I can see some errors

Dec  8 11:57:36 still-katydid dockerd[9606]: time="2022-12-08T11:57:36.486272382Z" level=warning msg="Your kernel does not support cgroup blkio weight"
Dec  8 11:57:36 still-katydid dockerd[9606]: time="2022-12-08T11:57:36.486290117Z" level=warning msg="Your kernel does not support cgroup blkio weight_device"
Dec  8 11:57:36 still-katydid dockerd[9606]: time="2022-12-08T11:57:36.487001498Z" level=info msg="Loading containers: start."
Dec  8 11:57:36 still-katydid dockerd[9606]: time="2022-12-08T11:57:36.489111401Z" level=warning msg="Running modprobe bridge br_netfilter failed with message: modprobe: WARNING: Module bridge not found in directory /lib/modules/4.18.0-372.9.1.el8.x86_64\nmodprobe: WARNING: Module br_netfilter not found in directory /lib/modules/4.18.0-372.9.1.el8.x86_64\n, error: exit status 1"
Dec  8 11:57:36 still-katydid dockerd[9606]: time="2022-12-08T11:57:36.591405424Z" level=info msg="Default bridge (docker0) is assigned with an IP address 172.17.0.0/16. Daemon option --bip can be used to set a preferred IP address"

I know the proxy address settings are correct, as I also have them configured in my .bashrc file and I can curl addresses such https://www.bbc.co.uk successfully.

The firewall is disabled on both the host and in the container.

I have rebooted the container and the host multiple times.

I solved my issue. I had a special character ! in my password. I had already escaped it with %21 but it turns out that docker requires a double %%.

So for docker proxy passwords a ! character needs to be escaped with %%21

There is more info available here https://docs.docker.com/config/daemon/systemd/