Description
openedon Apr 21, 2024
Description
I use Compose. I have two networks:
private(bridge, internal)public(bridge)
I have these containers:
wireguard- in both networksprivateandpublicat the same time. Provides VPN. Single instance only.worker- in networkprivateonly. Multiple instances. These have adnsconfig added with a public DNS server IP to allow resolution of public domains.
Objective: The worker internet traffic must only ever go through wireguard and never leave the host machine directly. Local DNS must continue to work so the containers can resolve each other's IPs and talk to each other. Internet DNS must also resolve.
Issue 1: This is difficult to setup because Docker networking does not have the right tools for the job. It is not possible to change a network's default gateway to point to a container IP.
Solution for issue 1: I added NET_ADMIN capability to worker and used this script to change the default route:
wireguard_ip=$(getent hosts wireguard | awk '{ print $1 }')
ip route replace default via $wireguard_ipIssue 2: With NET_ADMIN capability, nothing prevents the container from changing the default route again and pointing back to the Docker default gateway, at which point it would bypass the VPN traffic.
Solution for 2: That's why I use the internal network flag on private, which adds iptables firewall rules that prevent traffic from leaving that network completely.
Issue 3: These iptables rules block all traffic with IPs outside of the private CIDR. So it won't let traffic pass through the wireguard VPN because the IPs fall outside of the private CIDR.
Solution for 3:
I created another container with capability NET_ADMIN and critically with network_mode: host. This container then adds more iptables rules to the DOCKER-USER chain. It runs:
iptables -N ACCEPT-TO-INTERNET
iptables -A ACCEPT-TO-INTERNET -d 10.0.0.0/8 -j RETURN
iptables -A ACCEPT-TO-INTERNET -d 172.16.0.0/12 -j RETURN
iptables -A ACCEPT-TO-INTERNET -d 192.168.0.0/16 -j RETURN
iptables -A ACCEPT-TO-INTERNET -j ACCEPT
iptables -N ACCEPT-FROM-INTERNET
iptables -A ACCEPT-FROM-INTERNET -s 10.0.0.0/8 -j RETURN
iptables -A ACCEPT-FROM-INTERNET -s 172.16.0.0/12 -j RETURN
iptables -A ACCEPT-FROM-INTERNET -s 192.168.0.0/16 -j RETURN
iptables -A ACCEPT-FROM-INTERNET -j ACCEPT
iptables -I DOCKER-USER -i private -o private -j ACCEPT-TO-INTERNET
iptables -I DOCKER-USER -i private -o private -j ACCEPT-FROM-INTERNETThis will allow traffic destined to internet IPs to be exchanged between private containers. Crucially, it still blocks traffic that is sent to the Docker's original default route, but allows internet traffic to go to the wireguard container.
The reason I chose to do this setup in a container is because I wanted the entire application to be self-contained and portable, instead of relying on host machine startup scripts.
After jumping through all the hoops above, I got my networking setup working. Traffic goes from worker in private via wireguard in private, and exits via wireguard in public but now in a VPN tunnel. The worker containers cannot bypass this even if they get hacked and change their default route.
Now for the actual issue I have: this setup worked fine all the way to v4.28.0 (139021). Traffic went through correctly. Local DNS resolved correctly. Internet DNS also resolved correctly. After updating to v4.29.0 (145265), the internet DNS no longer works. Cannot resolve internet names. Local resolution continues to work. Traffic still flows through correctly, I can ping 8.8.8.8 from worker just fine.
I could do something like echo "nameserver 8.8.8.8" > /etc/resolv.conf in worker and that would allow me to resolve internet names but also prevent me from resolving local Docker names. I do not know what changed or where between v4.28 and v4.29, but internet resolution no longer works since v4.29.
Reproduce
As you can see, this is a pretty elaborate setup which also requires an active WireGuard connection, the latter I cannot provide for you. If necessary, I can make a repository to put my docker-compose.yaml in there together with the .sh scripts, but it will require you to supply your own WireGuard config anyway. Let me know what you need.
Expected behavior
No response
docker version
Client:
Cloud integration: v1.0.35+desktop.13
Version: 26.0.0
API version: 1.45
Go version: go1.21.8
Git commit: 2ae903e
Built: Wed Mar 20 15:14:46 2024
OS/Arch: darwin/amd64
Context: desktop-linux
Server: Docker Desktop 4.29.0 (145265)
Engine:
Version: 26.0.0
API version: 1.45 (minimum version 1.24)
Go version: go1.21.8
Git commit: 8b79278
Built: Wed Mar 20 15:18:01 2024
OS/Arch: linux/amd64
Experimental: false
containerd:
Version: 1.6.28
GitCommit: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
runc:
Version: 1.1.12
GitCommit: v1.1.12-0-g51d5e94
docker-init:
Version: 0.19.0
GitCommit: de40ad0docker info
Client:
Version: 26.0.0
Context: desktop-linux
Debug Mode: false
Plugins:
buildx: Docker Buildx (Docker Inc.)
Version: v0.13.1-desktop.1
Path: /Users/xxx/.docker/cli-plugins/docker-buildx
compose: Docker Compose (Docker Inc.)
Version: v2.26.1-desktop.1
Path: /Users/xxx/.docker/cli-plugins/docker-compose
debug: Get a shell into any image or container. (Docker Inc.)
Version: 0.0.27
Path: /Users/xxx/.docker/cli-plugins/docker-debug
dev: Docker Dev Environments (Docker Inc.)
Version: v0.1.2
Path: /Users/xxx/.docker/cli-plugins/docker-dev
extension: Manages Docker extensions (Docker Inc.)
Version: v0.2.23
Path: /Users/xxx/.docker/cli-plugins/docker-extension
feedback: Provide feedback, right in your terminal! (Docker Inc.)
Version: v1.0.4
Path: /Users/xxx/.docker/cli-plugins/docker-feedback
init: Creates Docker-related starter files for your project (Docker Inc.)
Version: v1.1.0
Path: /Users/xxx/.docker/cli-plugins/docker-init
sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
Version: 0.6.0
Path: /Users/xxx/.docker/cli-plugins/docker-sbom
scout: Docker Scout (Docker Inc.)
Version: v1.6.3
Path: /Users/xxx/.docker/cli-plugins/docker-scout
WARNING: Plugin "/Users/xxx/.docker/cli-plugins/docker-scan" is not valid: failed to fetch metadata: fork/exec /Users/xxx/.docker/cli-plugins/docker-scan: no such file or directory
Server:
Containers: 3
Running: 3
Paused: 0
Stopped: 0
Images: 6
Server Version: 26.0.0
Storage Driver: overlay2
Backing Filesystem: extfs
Supports d_type: true
Using metacopy: false
Native Overlay Diff: true
userxattr: false
Logging Driver: json-file
Cgroup Driver: cgroupfs
Cgroup Version: 2
Plugins:
Volume: local
Network: bridge host ipvlan macvlan null overlay
Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
Swarm: inactive
Runtimes: io.containerd.runc.v2 runc
Default Runtime: runc
Init Binary: docker-init
containerd version: ae07eda36dd25f8a1b98dfbf587313b99c0190bb
runc version: v1.1.12-0-g51d5e94
init version: de40ad0
Security Options:
seccomp
Profile: unconfined
cgroupns
Kernel Version: 6.6.22-linuxkit
Operating System: Docker Desktop
OSType: linux
Architecture: x86_64
CPUs: 8
Total Memory: 1.92GiB
Name: docker-desktop
ID: c0a42fb8-518b-45f0-b43c-4b30d10147a9
Docker Root Dir: /var/lib/docker
Debug Mode: false
HTTP Proxy: http.docker.internal:3128
HTTPS Proxy: http.docker.internal:3128
No Proxy: hubproxy.docker.internal
Labels:
com.docker.desktop.address=unix:///Users/xxx/Library/Containers/com.docker.docker/Data/docker-cli.sock
Experimental: false
Insecure Registries:
hubproxy.docker.internal:5555
127.0.0.0/8
Live Restore Enabled: false
WARNING: daemon is not using the default seccomp profileDiagnostics ID
a
Additional Info
No response