Prepare required Docker environments

1. Pre-defined environment

• Internet availabe host: localhost
• Air-gaped host: master01.airgapped.org

2. Pre-request

• You have to use the same linux distribution with your air-gaped host, which is master01.airgapped.org, in this artical we adopt CentOS 7 as host system.
• You'd have to obtain a PURE linux environment which HAVE Internet access without any post-installed packages as was installed in master01.airgapped.org. Otherwise you may encounter failed dependencies for docker in the master01.airgapped.org.
• We assume that you have a PURE Internet access availabe host named localhost.

2.1 Download and install the required packages for Docker

• On the localhost , run following commands:

mkdir ~/rpms
sudo yum update && yum install -y --downloadonly  --downloaddir=${HOME}/rpms docker
ssh [email protected] mkdir packages
#You can verify the outcome by type
ssh [email protected] "pwd && ls"
scp ${HOME}/rpms/* [email protected]:~/packages

• On the master01.airgapped.org , run following commands to install Docker environment

cd ~/packages
sudo rpm -ivh *

​If you encoutner missing depandency error like

warning: audit-libs-python-2.7.6-3.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY
error: Failed dependencies:
libyajl.so.2()(64bit) is needed by oci-systemd-hook-1:0.1.14-1.git1ba44c6.el7.x86_64
libyajl.so.2()(64bit) is needed by oci-umount-2:2.3.0-1.git51e7c50.el7.x86_64
libcgroup is needed by policycoreutils-python-2.5-17.1.el7.x86_64
​On the localhost you can run

sudo yum update && yum reinstall -y --downloadonly  --downloaddir=${HOME}/rpms missing-packages(like yajl libcgroup)

​And redo the scp command for the missing rpms.

2.2 Setup Docker environment and Shoot!

• On the master01.airgapped.org , following the procedure defined in Manage Docker as a non-root user to add docker user group.

sudo groupadd docker
sudo usermod -aG docker $USER

You have to re-login to make current $USER group affect.

• On the master01.airgapped.org , disable SeLinux in order to allow docker container access the host path file.

sudo setenforce 0
sudo sed 's/SELINUX=enforcing/SELINUX=permissive/g' /etc/selinux/config > /etc/selinux/config

Verify the whether selinux is disabled:

$ getenforce
Permissive

• On the master01.airgapped.org , enable and start the docker deamon.

sudo systemctl enable docker && sudo systemctl start docker

• On the master01.airgapped.org , check whether the docker's cgroupdriver is set to systemd --exec-opt native.cgroupdriver=systemd

cat  /usr/lib/systemd/system/docker.service

If not:

• Edit the /usr/lib/systemd/system/docker.service file and add --exec-opt native.cgroupdriver=systemd to /usr/lib/systemd/system/docker.service's ExecStart strings.
• Restart the docker deamon service with

  sudo systemctl reload-deamon docker && sudo systemctl restart docker
  

• On the master01.airgapped.org , check whether docker start successfully.

  systemctl status docker
  

Setup private registry service

3. Pre-request

• You have pulled the newset docker registry image from docker.io and export it to the tar archive.

    docker pull registry \
    && docker save docker.io/registry:latest -o docker-io.registry.tar
  

• You have to import the registry image to the master01.airgapped.org docker image repo cache
  On master01.airgapped.org

   docker load -i docker-io.registry.tar
  

3.1 Create HTTPS certificates required for docker private registry

This procedure follows the example on Openssl certificate creation on k8s official document
On master01.airgapped.org ：

• Prepare cert storage directory

  sudo mkdir /usr/lib/certs -p
  pushd /usr/lib/certs
  

• Generate CA key file

  sudo openssl genrsa -out ca.key 2048
  

• Generate CA certificate file

  sudo openssl req -x509 -new -nodes -key ca.key -subj "/CN=${MASTER_IP}" -days 10000 -out ca.crt
  

You can replace ${MASTER_IP} with your actual or persuade CA server ip address like

    sudo openssl req -x509 -new -nodes -key ca.key -subj "/CN=8.8.8.8" -days 10000 -out ca.crt

• Generate docker docker registry server key file

sudo openssl genrsa -out private-registry-server.key 2048

• Create a config file for generating a Certificate Signing Request (CSR) for docker registry server

cat > /tmp/private-registry-server.conf <<EOF
[ req ]
default_bits = 2048
prompt = no
default_md = sha256
req_extensions = req_ext
distinguished_name = dn

[ dn ]
C = cn #replace with actual info
ST = Tianjin #replace with actual info
L = Tianjin #replace with actual info
O = Air Gaped Company #replace with actual info
OU = Air Gaped team #replace with actual info
CN = master01.airgapped.org  #replace with actual registry server name

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = master01.airgapped.org #replace with alternative dns resolve name
DNS.2 = registry.airgapped.org #replace with alternative dns resolve name
IP.1 = 192.168.122.163 #replace with actuel ip for the registry server

[ v3_ext ]
authorityKeyIdentifier=keyid,issuer:always
basicConstraints=CA:FALSE
keyUsage=keyEncipherment,dataEncipherment
extendedKeyUsage=serverAuth,clientAuth
subjectAltName=@alt_names
EOF

sudo scp /tmp/private-registry-server.conf ./

• Generate the certificate signing request based on the config file for docker registry server

sudo openssl req -new -key  private-registry-server.key \
-out private-registry-server.csr \
-config private-registry-server.conf

• Sign the registry server certificate with CA cert and docker registry server CSR file

sudo openssl x509 -req -in private-registry-server.csr -CA ca.crt -CAkey ca.key \
-CAcreateserial -out private-registry-server.crt -days 10000 \
-extensions v3_ext -extfile private-registry-server.conf

• Verify the final cert for registry server

openssl x509  -noout -text -in private-registry-server.crt

3.2 Start private registry

• Copy the CA certificate to docker's certs directory to avoid insecur repository error, the directory which certs resides in must have the same hostname with the private registry domain name.

sudo mkdir /etc/docker/certs.d/registry.airgapped.org -p
sudo cp /usr/lib/certs/ca.crt /etc/docker/certs.d/registry.airgapped.org

• Run registry container with preset certs and port config

sudo mkdir /mnt/docker_images
docker run -d --restart=always -v /mnt/docker_images:/var/lib/registry \
   -v /usr/lib/certs:/cert \
   -e REGISTRY_HTTP_TLS_CERTIFICATE=/cert/private-registry-server.crt \
   -e REGISTRY_HTTP_TLS_KEY=/cert/private-registry-server.key \
   -e REGISTRY_HTTP_ADDR=0.0.0.0:443 \
   -p 443:443 --name local-registry registry

• Verify private registry successfully started and listen on assigned port

  docker logs local-registry
  

  You should see the following output like,with listening on [::]:443

  time="2017-12-18T12:57:53Z" level=warning msg="No HTTP secret provided - generated random secret. This may cause problems with uploads if multiple registries are behind a load-balancer. To provide a shared secret, fill in http.secret in the configuration file or set the REGISTRY_HTTP_SECRET environment variable." go.version=go1.7.6 instance.id=df382424-0e5d-49ad-b758-2b7b3e92d32f version=v2.6.2
  time="2017-12-18T12:57:53Z" level=info msg="redis not configured" go.version=go1.7.6 instance.id=df382424-0e5d-49ad-b758-2b7b3e92d32f version=v2.6.2
  time="2017-12-18T12:57:53Z" level=info msg="Starting upload purge in 37m0s" go.version=go1.7.6 instance.id=df382424-0e5d-49ad-b758-2b7b3e92d32f version=v2.6.2
  time="2017-12-18T12:57:54Z" level=info msg="using inmemory blob descriptor cache" go.version=go1.7.6 instance.id=df382424-0e5d-49ad-b758-2b7b3e92d32f version=v2.6.2
  time="2017-12-18T12:57:54Z" level=info msg="listening on [::]:443, tls" go.version=go1.7.6 instance.id=df382424-0e5d-49ad-b758-2b7b3e92d32f version=v2.6.2

• Append registry.airgapped.org domain to /etc/hosts, as dedicate domain for registry service

sudo sh -c 'echo "192.168.122.163 registry.airgapped.org" >> /etc/hosts'

If every thing is ok, you shall see the result by verifing the registry v2 API

curl --cacert /usr/lib/certs/ca.crt https://registry.airgapped.org/v2/_catalog
{"repositories":[]}

3.3 Push your first image to private registry and verify

On master01.airgapped.org, At this point, you have:

• one available private registry which is host on master01.airgapped.org and with a dedicate domain name registry.airgapped.org with TLS enabled, listening on port 443.
• one local image named docker.io/registry:latest cached on master01.airgapped.org , as:

  $ docker images
  REPOSITORY                       TAG                 IMAGE ID            CREATED             SIZE
  docker.io/registry               latest              177391bcf802        2 weeks ago         33.26 MB
  

Now you can verify the service by the following scripts:
3.3.1. Tag cached image with new registry path which leads to registry.airgapped.org
bash $ docker tag docker.io/registry:latest registry.airgapped.org/registry:latest $ docker images REPOSITORY TAG IMAGE ID CREATED SIZE registry.airgapped.org/registry latest 177391bcf802 2 weeks ago 33.26 MB docker.io/registry latest 177391bcf802 2 weeks ago 33.26 MB
3.3.2. Push newly taged image to registry.airgapped.org
bash docker push registry.airgapped.org/registry
3.3.3. Remove cached image on local docker, newly tag registry.airgapped.org/registry:latest
bash docker rmi registry.airgapped.org/registry:latest $ docker images REPOSITORY TAG IMAGE ID CREATED SIZE docker.io/registry latest 177391bcf802 2 weeks ago 33.26 MB
3.3.4. Pull image registry from registry.airgapped.org
```bash
$ docker pull registry.airgapped.org/registry
Using default tag: latest
Trying to pull repository registry.airgapped.org/registry ...
latest: Pulling from registry.airgapped.org/registry
Digest: sha256:e82c444f6275eaca07889d471943668ac17fd03ea8d863289a54c199ed216332

$ docker images
REPOSITORY                       TAG                 IMAGE ID            CREATED             SIZE
docker.io/registry               latest              177391bcf802        2 weeks ago         33.26 MB
registry.airgapped.org/registry   latest              177391bcf802        2 weeks ago         33.26 MB
```

Now, you have a working and verified private registry!

For securer docker access, you shall follow the instruction list on Restricting access.