Bug: systemd-resolved issues #580
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mageddo
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discussion
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Hey @ratcashdev , DPS won´t be able to configure itself as the default DNS when running inside a docker container when the host is using system-resolved. Yep, you will do need to restart systemd-resolved using service or systemctl command, see more details about the limitation. If you are using DPS as your primary DNS solver I would recommend follow theses steps to configure it as a service and don't have to reconfigure systemd-resolved at every restart. In alternative you can bypass systemd-resolved and use resolv.conf without the need to restart any service by following these instructions: services:
dns-proxy:
image: defreitas/dns-proxy-server
hostname: dns
volumes:
- type: bind
source: /var/run/docker.sock
target: /var/run/docker.sock
- type: bind
source: /etc
target: /host/etc
environment:
- MG_RESOLVCONF=/host/etc/resolv.conf
ports:
- "5380:5380" |
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HI @mageddo thanks for the quick replay and solution.
can you plz elaborate what is the fundamental issue here? |
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Basically systemd-resolved need to be restarted and it's a host program, a host program can't be executed from the docker container as expected by the isolation principle, DPS is running inside a docker container so it can´t restart the host system-resolved at the host. |
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@mageddo I have tried your suggested setup above. Unfortunately, it seems it still does not work.
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I will do a check, looks like DPS hasn't permission to edit |
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yeah, pretty much: |
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Got it.
# ls -lha /host/etc/resolv*
lrwxrwxrwx 1 root root 39 Sep 15 2022 /host/etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.confSo you need to run like below: services:
dns-proxy:
image: defreitas/dns-proxy-server
hostname: dns
volumes:
- /run/systemd/resolve/:/host/run/
environment:
MG_RESOLVCONF: /host/run/stub-resolv.conf
ports:
- "5380:5380"
Improving the logs to make the failing condition explicit at #585 . |
mageddo
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discussion
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This issue is stale because it has been waiting-feedback for 15 days with no activity. |
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This issue was closed because it has been inactive for 7 days since being marked as stale, you can reopen it at any time. |
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Tested this today. Unfortunately, it still does not work. Logs look good, but a simple ping to a hostname registered in the compose file fails. logs: /etc/resolv.conf (linked to /run/systemd/resolve/stub-resolv.conf) now looks like this: |
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@ratcashdev can you confirm that DPS is being used as the default DNS? can you see query entries at DPS logs? If your /etc/resolv.conf keeps with You can ping |
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@mageddo unfortunately none of the pings work and I don't see any name queries in the DPS logs. |
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Looks like systemd-resolved is acting and ignoring resolv.conf. If you really want to run DPS inside docker container you can set an static IP for DPS container and configure it on systemd-resolved as following (you will need to use DPS 3.30.5-snapshot): services:
dns-proxy:
image: defreitas/dns-proxy-server:3.30.5-snapshot
hostname: dns
volumes:
- type: bind
source: /var/run/docker.sock
target: /var/run/docker.sock
networks:
my_network:
ipv4_address: 171.18.0.10
environment:
- MG_LOG_LEVEL=DEBUG
networks:
my_network:
driver: bridge
ipam:
config:
- subnet: 171.18.0.0/16Locate the DNS= line in the [Resolve] section and add the container's static IP: [Resolve]
DNS=171.18.0.10
FallbackDNS=Restart the systemd-resolved service to apply the changes: DPS will be used when available sudo systemctl restart systemd-resolved |
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Thanks for the suggestion. My primary use case was to start dns-proxy from inside docker-compose to allow seamless communication between the host and other containers using host names during integration testing. The requirement to restart resolved makes this a non-practical approach (to the extent of being practically unusable) for my use case. |
What is Happening
starting dns-proxy from within a compose file, like:
ping dnsexecuted from the host saysName or service not knownThe logs, in addition contain the entry:
Not possible to restart resolved service: service systemd-resolved restartActually, the command
serviceis not present on my machine. Onlysystemctl restart systemd-resolvedworks.However, even if I restart
resolvedmanually, DNS lookup does not work through dns-proxy.What is Expected
systemd-resolved is restarted and DNS lookup works.
Specs
docker version27.1.2docker run --rm defreitas/dns-proxy-server --version3.25.10-snapshotThe text was updated successfully, but these errors were encountered: