nss-docker-ng is a NSS plugin for finding Docker containers by their ID or name.
The container names are searched in a virtual domain name .docker.
Install it, then try:
$ docker run --name my-app -d hashicorp/http-echo -listen=:80 -text="✅ it works!"
04e8b7ccf6215a17064ec0d15d4235d5c62c461bc26a681c8ee64344bb0dc2df
$ getent hosts my-app.docker
172.17.0.4 my-app.docker 04e8b7ccf621.docker
$ curl http://my-app.docker
✅ it works!
$ ping my-app.docker
PING test.docker (172.17.0.4) 56(84) bytes of data.
64 bytes from 172.17.0.4: icmp_seq=1 ttl=64 time=0.171 ms
$ docker stop my-app
You can have nss-docker-ng respond to all subdomains for a container by setting the label .com.github.petski.nss-docker-ng.container-subdomains-allowed to true, True or 1.
$ docker run --name my-app-with-subdomains -d --label=".com.github.petski.nss-docker-ng.container-subdomains-allowed=true" hashicorp/http-echo -listen=:80 -text="✅ it works!"
670b3dc0aa2761d0fa150180e1cc1769d5e7e5a3332c12562197c7a782ed8a94
$ getent hosts my-app-with-subdomains.docker
172.29.0.2 my-app-with-subdomains.docker 670b3dc0aa27.docker
$ getent hosts foo.my-app-with-subdomains.docker
172.29.0.2 my-app-with-subdomains.docker 670b3dc0aa27.docker foo.my-app-with-subdomains.docker
$ docker stop my-app-with_subdomains
DESTDIR="/usr/local/lib/nss-docker-ng/" && \
sudo --preserve-env=DESTDIR install -m 0755 -d "$DESTDIR" && \
curl -sL 'https://github.com/petski/nss-docker-ng/releases/latest/download/libnss_docker_ng.so' -o - | sudo --preserve-env=DESTDIR tee "${DESTDIR}/libnss_docker_ng.so" > /dev/null && \
echo "${DESTDIR}" | sudo tee /etc/ld.so.conf.d/nss-docker-ng.conf > /dev/null && \
sudo /sbin/ldconfig
Then, add the docker_ng service to the hosts:-line in /etc/nsswitch.conf. For example: hosts: files docker_ng dns
sudo add-apt-repository ppa:petski/ubuntu/nss-docker-ng && \
sudo apt install nss-docker-ng
You'll need at least git, cargo and patchelf.
git clone https://github.com/petski/nss-docker-ng.git
cd nss-docker-ng
cargo build --release && \
patchelf --set-soname libnss_docker_ng.so.2 target/release/libnss_docker_ng.so && \
DESTDIR="/usr/local/lib/nss-docker-ng/" && \
sudo --preserve-env=DESTDIR install -m 0755 -d "$DESTDIR" && \
sudo --preserve-env=DESTDIR install -m 0644 target/release/libnss_docker_ng.so "${DESTDIR}/libnss_docker_ng.so" && \
echo "${DESTDIR}" | sudo tee /etc/ld.so.conf.d/nss-docker-ng.conf > /dev/null && \
sudo /sbin/ldconfig
Then, add the docker_ng service to the hosts:-line in /etc/nsswitch.conf. For example: hosts: files docker_ng dns
Contributions are welcome! Nothing to contribute, but you do appreciate this software? Please star ⭐ this repo.
cargo build && \
patchelf --set-soname libnss_docker_ng.so.2 target/debug/libnss_docker_ng.so && \
DESTDIR="/usr/local/lib/nss-docker-ng/" && \
sudo --preserve-env=DESTDIR install -m 0755 -d "$DESTDIR" && \
sudo --preserve-env=DESTDIR install -m 0644 target/debug/libnss_docker_ng.so "${DESTDIR}/libnss_docker_ng.so" && \
echo "${DESTDIR}" | sudo tee /etc/ld.so.conf.d/nss-docker-ng.conf > /dev/null && \
sudo /sbin/ldconfig
getent hosts not-existing-container.docker
# Failed to inspect container 'not-existing-container': error 404 Not Found - No such container: not-existing-container
There are other options to achieve this feature. I'm comparing them HERE.