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nginxdockerprivilegesbasic-authenticationdocker-registry

How to make pull public and push requiring login in docker registry v2?

I started the registry as composed containers using this instruction : https://www.digitalocean.com/community/tutorials/how-to-set-up-a-private-docker-registry-on-ubuntu-14-04

However I would like to differentiate access, so anyone without logging in have access to pull the images from repository, but cannot push.

At the first approach I tried to achieve that by setting in nginx (because I used it for frontend like in the tutorial) limit_except

limit_except GET HEAD {
    auth_basic "Docker Registry";
    auth_basic_user_file /etc/nginx/conf.d/registry.password;
}

Unfortunately thus the pull works smoothly but docker login command doesn't work.

$ docker login myhost.example.net
Username: myuser
Password: 
Email: 
Error response from daemon: no successful auth challenge for https://myhost.example.net/v2/ - errors: []

As it appears, both docker pull and docker login sends the same HTTP GET request and it is hard to differentiate between them.

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

Now let's look at different requests and analyze it.

Docker login (with http basic turned on):

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 401 Unauthorized
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:40:40 GMT
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
WWW-Authenticate: Basic realm="Docker Registry"
Docker-Distribution-Api-Version: registry/2.0

<html>
<head><title>401 Authorization Required</title></head>
<body bgcolor="white">
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx/1.9.9</center>
</body>
</html>
GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Authorization: Basic eHh4Onh4eAo=
Accept-Encoding: gzip

HTTP/1.1 200 OK
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:40:40 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 2
Connection: keep-alive
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Docker-Distribution-Api-Version: registry/2.0

Docker login (with http basic turned off)

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 200 OK
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 10:09:26 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 2
Connection: keep-alive
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Docker-Distribution-Api-Version: registry/2.0

After receiving 200 OK, the command fails like mentioned above.

Docker pull (with http basic turned off):

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 200 OK
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:53:54 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 2
Connection: keep-alive
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Docker-Distribution-Api-Version: registry/2.0

{}GET /v2/my-ubuntu-image/manifests/latest HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 200 OK
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:53:54 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 39196
Connection: keep-alive
Docker-Content-Digest: sha256:8b6bef1314e51d06ab2f89af1f1d2c486245d4c2b1b3c169812b479c12f5410e
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:8b6bef1314e51d06ab2f89af1f1d2c486245d4c2b1b3c169812b479c12f5410e"
X-Content-Type-Options: nosniff
Docker-Distribution-Api-Version: registry/2.0

{
 ... (truncated) ...

Docker pull (with http basic turned on, with crendentials):

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 401 Unauthorized
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:52:00 GMT
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
WWW-Authenticate: Basic realm="Docker Registry"
Docker-Distribution-Api-Version: registry/2.0

<html>
<head><title>401 Authorization Required</title></head>
<body bgcolor="white">
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx/1.9.9</center>
</body>
</html>
GET /v2/my-ubuntu-image/manifests/latest HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Authorization: Basic cmZzY206d2llbGJyZnNjbXBvd3N6ZWN6YXN5
Accept-Encoding: gzip

HTTP/1.1 200 OK
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:52:00 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 39196
Connection: keep-alive
Docker-Content-Digest: sha256:8b6bef1314e51d06ab2f89af1f1d2c486245d4c2b1b3c169812b479c12f5410e
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:8b6bef1314e51d06ab2f89af1f1d2c486245d4c2b1b3c169812b479c12f5410e"
X-Content-Type-Options: nosniff
Docker-Distribution-Api-Version: registry/2.0
... (truncated) ...

Docker pull (with http basic turned on, without crendentials):

GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 401 Unauthorized
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:39:54 GMT
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
WWW-Authenticate: Basic realm="Docker Registry"
Docker-Distribution-Api-Version: registry/2.0

<html>
<head><title>401 Authorization Required</title></head>
<body bgcolor="white">
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx/1.9.9</center>
</body>
</html>
GET /v2/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Accept-Encoding: gzip

HTTP/1.1 401 Unauthorized
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:39:54 GMT
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
WWW-Authenticate: Basic realm="Docker Registry"
Docker-Distribution-Api-Version: registry/2.0

<html>
<head><title>401 Authorization Required</title></head>
<body bgcolor="white">
<center><h1>401 Authorization Required</h1></center>
<hr><center>nginx/1.9.9</center>
</body>
</html>
GET /v1/repositories/my-ubuntu-image/images HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
X-Docker-Token: true
Accept-Encoding: gzip

HTTP/1.1 404 Not Found
Server: nginx/1.9.9
Date: Tue, 05 Jan 2016 09:39:54 GMT
Content-Type: text/html
Content-Length: 168
Connection: keep-alive

<html>
<head><title>404 Not Found</title></head>
<body bgcolor="white">
<center><h1>404 Not Found</h1></center>
<hr><center>nginx/1.9.9</center>
</body>
</html>

By looking at the last example we can clearly see when pull doesn't have credentials tries twice to access url /v2/, so maybe we can differentiate the request in some way, when the client ask for /v2/ url twice in row ?

I also heard that the newest registry (I think version >= 2.1) has built-in support for HTTP Basic Auth, but I cannot find that in docs.

I hope I explained the case thoroughly.

Solution

  • I am answering myself, as I found the issue thread on the Docker's github. The case seems very complex. Because the registry specification is open is hard to tell who is the one to blame, the docker tools or the registry.

    Please look at the issue here and the other related: https://github.com/docker/distribution/issues/1230

    Portus seems interesting alternative. Thanks, @{Jonathon Reinhart}! I will give it a try later on.

    For now I will just limit the POST request and PUT requests to the ones from the local address or localhost (you can push ommiting the nginx).

    POST /v2/superpartia/blobs/uploads/ HTTP/1.1
Host: myhost.example.net
User-Agent: docker/1.9.1 go/go1.4.2 git-commit/a34a1d5 kernel/4.2.0-19-generic os/linux arch/amd64
Content-Length: 0
Authorization: Basic eHh4Onh4eA==
Content-Type: 
Accept-Encoding: gzip
ked from local address

    So I limit only everything other than GET and HEAD (HEAD is implied by GET, look at the nginx manual)

    location /v2/ {
...
    limit_except GET {
        allow 172.x.x.x;
        deny all;
    }
...

    This way push is blocked:

    Error parsing HTTP response: invalid character '<' looking for beginning of value: "<html>\r\n<head><title>403 Forbidden</title></head>\r\n<body bgcolor=\"white\">\r\n<center><h1>403 Forbidden</h1></center>\r\n<hr><center>nginx/1.9.9</center>\r\n</body>\r\n</html>\r\n"