https://github.com/kevinjqiu/coredns-dockerdiscovery

Docker Discovery Plugin for CoreDNS
https://github.com/kevinjqiu/coredns-dockerdiscovery

coredns coredns-plugin discovery docker

Last synced: 3 days ago
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Docker Discovery Plugin for CoreDNS

• Host: GitHub
• URL: https://github.com/kevinjqiu/coredns-dockerdiscovery
• Owner: kevinjqiu
• License: apache-2.0
• Created: 2018-04-21T04:22:29.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2024-03-25T13:47:31.000Z (8 months ago)
• Last Synced: 2024-04-17T19:24:23.734Z (7 months ago)
• Topics: coredns, coredns-plugin, discovery, docker
• Language: Go
• Size: 72.3 KB
• Stars: 56
• Watchers: 3
• Forks: 29
• Open Issues: 10
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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• awesome-coredns - dockerdiscovery - Docker Discovery Plugin for CoreDNS (External Plguins)

README

        
coredns-dockerdiscovery

===================================

Docker discovery plugin for coredns

Name

----

dockerdiscovery - add/remove DNS records for docker containers.

Syntax

------

    docker [DOCKER_ENDPOINT] {

        domain DOMAIN_NAME

        hostname_domain HOSTNAME_DOMAIN_NAME

        network_aliases DOCKER_NETWORK

        label LABEL

        compose_domain COMPOSE_DOMAIN_NAME

    }

* `DOCKER_ENDPOINT`: the path to the docker socket. If unspecified, defaults to `unix:///var/run/docker.sock`. It can also be TCP socket, such as `tcp://127.0.0.1:999`.

* `DOMAIN_NAME`: the name of the domain for [container name](https://docs.docker.com/engine/reference/run/#name---name), e.g. when `DOMAIN_NAME` is `docker.loc`, your container with `my-nginx` (as subdomain) [name](https://docs.docker.com/engine/reference/run/#name---name) will be assigned the domain name: `my-nginx.docker.loc`

* `HOSTNAME_DOMAIN_NAME`: the name of the domain for [hostname](https://docs.docker.com/config/containers/container-networking/#ip-address-and-hostname). Work same as `DOMAIN_NAME` for hostname.

* `COMPOSE_DOMAIN_NAME`: the name of the domain when it is determined the

    container is managed by docker-compose.  e.g. for a compose project of

    "internal" and service of "nginx", if `COMPOSE_DOMAIN_NAME` is

    `compose.loc` the fqdn will be `nginx.internal.compose.loc`

* `DOCKER_NETWORK`: the name of the docker network. Resolve directly by [network aliases](https://docs.docker.com/v17.09/engine/userguide/networking/configure-dns) (like internal docker dns resolve host by aliases whole network)

* `LABEL`: container label of resolving host (by default enable and equals ```coredns.dockerdiscovery.host```)

How To Build

------------

    GO111MODULE=on go get -u github.com/coredns/coredns

    GO111MODULE=on go get github.com/kevinjqiu/coredns-dockerdiscovery

    cd ~/go/src/github.com/coredns/coredns

    echo "docker:github.com/kevinjqiu/coredns-dockerdiscovery" >> plugin.cfg

    cat plugin.cfg | uniq > plugin.cfg.tmp

    mv plugin.cfg.tmp plugin.cfg

    make all

    ~/go/src/github.com/coredns/coredns/coredns --version

Alternatively, you can use the following manual steps:

1. Checkout coredns:  `go get github.com/coredns/coredns`.

2. `cd $GOPATH/src/github.com/coredns/coredns`

3. `echo "docker:github.com/kevinjqiu/coredns-dockerdiscovery" >> plugin.cfg`

4. `go generate`

5. `make`

Alternatively, run insider docker container

    docker build -t coredns-dockerdiscovery .

    docker run --rm -v ${PWD}/Corefile:/etc/Corefile -v /var/run/docker.sock:/var/run/docker.sock -p 15353:15353/udp coredns-dockerdiscovery -conf /etc/Corefile

Run tests

    go test -v

Example

-------

`Corefile`:

    .:15353 {

        docker unix:///var/run/docker.sock {

            domain docker.loc

            hostname_domain docker-host.loc

        }

        log

    }

Start CoreDNS:

    $ ./coredns

    .:15353

    2018/04/26 22:36:32 [docker] start

    2018/04/26 22:36:32 [INFO] CoreDNS-1.1.1

    2018/04/26 22:36:32 [INFO] linux/amd64, go1.10.1,

    CoreDNS-1.1.1

Start a docker container:

    $ docker run -d --name my-alpine --hostname alpine alpine sleep 1000

    78c2a06ef2a9b63df857b7985468f7310bba0d9ea4d0d2629343aff4fd171861

Use CoreDNS as your resolver to resolve the `my-alpine.docker.loc` or `alpine.docker-host.loc`:

    $ dig @localhost -p 15353 my-alpine.docker.loc

    ; <<>> DiG 9.10.3-P4-Ubuntu <<>> @localhost -p 15353 my-alpine.docker.loc

    ; (1 server found)

    ;; global options: +cmd

    ;; Got answer:

    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61786

    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

    ;; OPT PSEUDOSECTION:

    ; EDNS: version: 0, flags:; udp: 4096

    ;; QUESTION SECTION:

    ;my-alpine.docker.loc.            IN      A

    ;; ANSWER SECTION:

    my-alpine.docker.loc.     3600    IN      A       172.17.0.2

    ;; Query time: 0 msec

    ;; SERVER: 127.0.0.1#15353(127.0.0.1)

    ;; WHEN: Thu Apr 26 22:39:55 EDT 2018

    ;; MSG SIZE  rcvd: 63

Stop the docker container will remove the corresponded DNS entries:

    $ docker stop my-alpine

    78c2a

    $ dig @localhost -p 15353 my-alpine.docker.loc

    ;; QUESTION SECTION:

    ;my-alpine.docker.loc.            IN      A

Container will be resolved by label as ```nginx.loc```

    docker run --label=coredns.dockerdiscovery.host=nginx.loc nginx

 See receipt [how install for local development](setup.md)