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Chapter 7. Docker tasks
OpenShift Container Platform uses Docker to run applications in pods that are composed by any number of containers.
As a cluster administrator, sometimes Docker requires some extra configuration in order to efficiently run elements of the OpenShift Container Platform installation.
7.1. Increasing Docker storage
Increasing the amount of storage available ensures continued deployment without any outages. To do so, a free partition must be made available that contains an appropriate amount of free capacity.
7.1.1. Evacuating the node
Procedure
- From a master instance, or as a cluster administrator, allow the evacuation of any pod from the node and disable scheduling of other pods on that node: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- If there are containers running with local volumes that will not migrate, run the following command: - oc adm drain ${NODE} --ignore-daemonsets --delete-local-data.
- List the pods on the node to verify that they have been removed: - oc adm manage-node ${NODE} --list-pods- $ oc adm manage-node ${NODE} --list-pods Listing matched pods on node: ose-app-node01.example.com NAME READY STATUS RESTARTS AGE- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
For more information on evacuating and draining pods or nodes, see Node maintenance.
7.1.2. Increasing storage
You can increase Docker storage in two ways: attaching a new disk, or extending the existing disk.
Increasing storage with a new disk
Prerequisites
- A new disk must be available to the existing instance that requires more storage. In the following steps, the original disk is labeled - /dev/xvdb, and the new disk is labeled- /dev/xvdd, as shown in the /etc/sysconfig/docker-storage-setup file:- vi /etc/sysconfig/docker-storage-setup - # vi /etc/sysconfig/docker-storage-setup DEVS="/dev/xvdb /dev/xvdd"- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- The process may differ depending on the underlying OpenShift Container Platform infrastructure. 
Procedure
- Stop the - dockerand- atomic-openshift-nodeservices:- systemctl stop docker atomic-openshift-node - # systemctl stop docker atomic-openshift-node- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Run the - docker-storage-setupcommand to extend the volume groups and logical volumes associated with container storage:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Start the Docker services: - systemctl start docker vgs - # systemctl start docker # vgs VG #PV #LV #SN Attr VSize VFree docker_vol 2 1 0 wz--n- 64.99g <55.00g- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- A benefit in adding a disk compared to creating a new volume group and re-running - docker-storage-setupis that the images that were used on the system still exist after the new storage has been added:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- With the increase in storage capacity, enable the node to be schedulable in order to accept new incoming pods. - As a cluster administrator, run the following from a master instance: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
Increasing storage with a new disk
- Evacuate the node following the previous steps.
- Stop the - dockerand- atomic-openshift-nodeservices:- systemctl stop docker atomic-openshift-node - # systemctl stop docker atomic-openshift-node- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Resize the existing disk as desired. This can can depend on your environment: - If you are using LVM (Logical Volume Manager): - lvremove /dev/docker_vg/docker/lv - # lvremove /dev/docker_vg/docker/lv- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Remove the Docker volume group: - vgremove docker_vg - # vgremove docker_vg- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- pvremove /dev/<my_previous_disk_device> - # pvremove /dev/<my_previous_disk_device>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
 
- If you are using a cloud provider, you can detach the disk, destroy the disk, then create a new bigger disk, and attach it to the instance.
- For a non-cloud environment, the disk and file system can be resized. See the following solution for more information: 
 
- Verify that the /etc/sysconfig/container-storage-setup file is correctly configured for the new disk by checking the device name, size, etc.
- Run - docker-storage-setupto reconfigure the new disk:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Start the Docker services: - systemctl start docker vgs - # systemctl start docker # vgs VG #PV #LV #SN Attr VSize VFree docker_vol 2 1 0 wz--n- 64.99g <55.00g- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Start the - atomic-openshift-nodeservice:- systemctl start atomic-openshift-node - # systemctl start atomic-openshift-node- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
7.1.3. Changing the storage backend
					With the advancements of services and file systems, changes in a storage backend may be necessary to take advantage of new features. The following steps provide an example of changing a device mapper backend to an overlay2 storage backend. overlay2 offers increased speed and density over traditional device mapper.
				
7.1.3.1. Evacuating the node
- From a master instance, or as a cluster administrator, allow the evacuation of any pod from the node and disable scheduling of other pods on that node: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- If there are containers running with local volumes that will not migrate, run the following command: - oc adm drain ${NODE} --ignore-daemonsets --delete-local-data
- List the pods on the node to verify that they have been removed: - oc adm manage-node ${NODE} --list-pods- $ oc adm manage-node ${NODE} --list-pods Listing matched pods on node: ose-app-node01.example.com NAME READY STATUS RESTARTS AGE- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - For more information on evacuating and draining pods or nodes, see Node maintenance. 
- With no containers currently running on the instance, stop the - dockerand- atomic-openshift-node serviceservices:- systemctl stop docker atomic-openshift-node - # systemctl stop docker atomic-openshift-node- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Verify the name of the volume group, logical volume name, and physical volume name: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Modify the - docker-storage-setupfile to specify the- STORAGE_DRIVER.Note- When a system is upgraded from Red Hat Enterprise Linux version 7.3 to 7.4, the - dockerservice attempts to use- /varwith the- STORAGE_DRIVERof extfs. The use of extfs as the- STORAGE_DRIVERcauses errors. See the following bug for more info regarding the error:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Set up the storage: - docker-storage-setup - # docker-storage-setup- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Start the - dockerand- atomic-openshift-nodeservices:- systemctl start docker atomic-openshift-node - # systemctl start docker atomic-openshift-node- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- With the storage modified to use - overlay2, enable the node to be schedulable in order to accept new incoming pods.- From a master instance, or as a cluster administrator: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
7.2. Managing Docker certificates
An OpenShift Container Platform internal registry is created as a pod. However, containers may be pulled from external registries if desired. By default, registries listen on TCP port 5000. Registries provide the option of securing exposed images via TLS or running a registry without encrypting traffic.
					Docker interprets .crt files as CA certificates and .cert files as client certificates. Any CA extensions must be .crt.
				
In order to use OpenShift Container Platform with an external registry, the registry certificate authority (CA) certificate must be trusted for all the nodes that can pull images from the registry.
						Depending on the Docker version, the process to trust a Docker registry varies. The latest versions of Docker’s root certificate authorities are merged with system defaults. Prior to docker version 1.13, the system default certificate is used only when no other custom root certificates exist.
					
Procedure
- Copy the CA certificate to - /etc/pki/ca-trust/source/anchors/:- sudo cp myregistry.example.com.crt /etc/pki/ca-trust/source/anchors/ - $ sudo cp myregistry.example.com.crt /etc/pki/ca-trust/source/anchors/- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Extract and add the CA certificate to the list of trusted certificates authorities: - sudo update-ca-trust extract - $ sudo update-ca-trust extract- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Verify the SSL certificate using the - opensslcommand:- openssl verify myregistry.example.com.crt - $ openssl verify myregistry.example.com.crt myregistry.example.com.crt: OK- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Once the certificate is in place and the trust is updated, restart the - dockerservice to ensure the new certificates are properly set:- sudo systemctl restart docker.service - $ sudo systemctl restart docker.service- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
For Docker versions prior to 1.13, perform the following additional steps for trusting certificates of authority:
- On every node create a new directory in - /etc/docker/certs.dwhere the name of the directory is the host name of the Docker registry:- sudo mkdir -p /etc/docker/certs.d/myregistry.example.com - $ sudo mkdir -p /etc/docker/certs.d/myregistry.example.com- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- The port number is not required unless the Docker registry cannot be accessed without a port number. Addressing the port to the original Docker registry is as follows: - myregistry.example.com:port
- Accessing the Docker registry via IP address requires the creation of a new directory within - /etc/docker/certs.don every node where the name of the directory is the IP of the Docker registry:- sudo mkdir -p /etc/docker/certs.d/10.10.10.10 - $ sudo mkdir -p /etc/docker/certs.d/10.10.10.10- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Copy the CA certificate to the newly created Docker directories from the previous steps: - sudo cp myregistry.example.com.crt \ /etc/docker/certs.d/myregistry.example.com/ca.crt sudo cp myregistry.example.com.crt /etc/docker/certs.d/10.10.10.10/ca.crt - $ sudo cp myregistry.example.com.crt \ /etc/docker/certs.d/myregistry.example.com/ca.crt $ sudo cp myregistry.example.com.crt /etc/docker/certs.d/10.10.10.10/ca.crt- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Once the certificates have been copied, restart the - dockerservice to ensure the new certificates are used:- sudo systemctl restart docker.service - $ sudo systemctl restart docker.service- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
7.2.2. Docker certificates backup
When performing a node host backup, ensure to include the certificates for external registries.
Procedure
- If using - /etc/docker/certs.d, copy all the certificates included in the directory and store the files:- sudo tar -czvf docker-registry-certs-$(hostname)-$(date +%Y%m%d).tar.gz /etc/docker/certs.d/ - $ sudo tar -czvf docker-registry-certs-$(hostname)-$(date +%Y%m%d).tar.gz /etc/docker/certs.d/- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- If using a system trust, store the certificates prior to adding them within the system trust. Once the store is complete, extract the certificate for restoration using the - trustcommand. Identify the system trust CAs and note the- pkcs11ID:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Extract the certificate in - pemformat and provide it a name. For example,- myca.crt.- trust extract --format=pem-bundle \ --filter="%a5%b3%e1%2b%2b%49%b6%d7%73%a1%aa%94%f5%01%e7%73%65%4c%ac%50;type=cert" myca.crt - $ trust extract --format=pem-bundle \ --filter="%a5%b3%e1%2b%2b%49%b6%d7%73%a1%aa%94%f5%01%e7%73%65%4c%ac%50;type=cert" myca.crt- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Verify the certificate has been properly extracted via - openssl:- openssl verify myca.crt - $ openssl verify myca.crt- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Repeat the procedure for all the required certificates and store the files in a remote location.
7.2.3. Docker certificates restore
In the event of the deletion or corruption of the Docker certificates for the external registries, the restore mechanism uses the same steps as the installation method using the files from the backups performed previously.
7.3. Managing Docker registries
				You can configure OpenShift Container Platform to use external docker registries to pull images. However, you can use configuration files to allow or deny certain images or registries.
			
If the external registry is exposed using certificates for the network traffic, it can be named as a secure registry. Otherwise, traffic between the registry and host is plain text and not encrypted, meaning it is an insecure registry.
7.3.1. Docker search external registries
					By default, the docker daemon has the ability to pull images from any registry, but the search operation is performed against docker.io/ and registry.access.redhat.com. The daemon can be be configured to search images from other registries using the --add-registry option with the docker daemon.
				
						The ability to search images from the Red Hat Registry registry.access.redhat.com exists by default in the Red Hat Enterprise Linux docker package.
					
Procedure
- To allow users to search for images using - docker searchwith other registries, add those registries to the- /etc/containers/registries.conffile under the- registriesparameter:- registries: - registry.access.redhat.com - my.registry.example.com - registries: - registry.access.redhat.com - my.registry.example.com- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Prior to OpenShift Container Platform version 3.6, this was accomplished using - /etc/sysconfig/dockerwith the following options:- ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com" - ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com"- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - The first registry added is the first registry searched. 
- Restart the - dockerdaemon to allow for- my.registry.example.comto be used:- sudo systemctl restart docker.service - $ sudo systemctl restart docker.service- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Restarting the - dockerdaemon causes the- dockercontainers to restart.
- Using the Ansible installer, this can be configured using the - openshift_docker_additional_registriesvariable in the Ansible hosts file:- openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com - openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
					Docker can be configured to block operations from external registries by configuring the registries and block_registries flags for the docker daemon.
				
Procedure
- Add the allowed registries to the - /etc/containers/registries.conffile with the- registriesflag:- registries: - registry.access.redhat.com - my.registry.example.com - registries: - registry.access.redhat.com - my.registry.example.com- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Prior to 3.6, the - /etc/sysconfig/dockerfile is modified instead:- ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com" - ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com"- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- The - docker.ioregistry can be added using the same method.
- Block the rest of the registries: - block_registries: - all - block_registries: - all- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Block the rest of the registries in older versions: - BLOCK_REGISTRY='--block-registry=all' - BLOCK_REGISTRY='--block-registry=all'- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Restart the - dockerdaemon:- sudo systemctl restart docker.service - $ sudo systemctl restart docker.service- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Restarting the - dockerdaemon causes the- dockercontainers to restart.
- In this example, the - docker.ioregistry has been blacklisted, so any operation regarding that registry fails:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Add - docker.ioback to the- registriesvariable by modifying the file again and restarting the service.- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - or - ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com --add-registry=docker.io" BLOCK_REGISTRY='--block-registry=all' - ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com --add-registry=docker.io" BLOCK_REGISTRY='--block-registry=all'- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Restart the Docker service: - sudo systemctl restart docker - $ sudo systemctl restart docker- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- To verify that the image is now available to be pulled: - Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- If using an external registry is required, for example to modify the - dockerdaemon configuration file in all the node hosts that require to use that registry, create a blacklist on those nodes to avoid malicious containers from being executed.- Using the Ansible installer, this can be configured using the - openshift_docker_additional_registriesand- openshift_docker_blocked_registriesvariables in the Ansible hosts file:- openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com openshift_docker_blocked_registries=all - openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com openshift_docker_blocked_registries=all- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
7.3.3. Secure registries
In order to be able to pull images from an external registry, it is required to trust the registry certificates, otherwise the pull image operation fails.
In order to do so, see the Installing a Certificate Authority Certificate for External Registries section.
					If using a whitelist, the external registries should be added to the registries variable, as explained above.
				
7.3.4. Insecure registries
External registries that use non-trusted certificates, or without certificates at all, should be avoided.
					However, any insecure registries should be added using the --insecure-registry option to allow for the docker daemon to pull images from the repository. This is the same as the --add-registry option, but the docker operation is not verified.
				
The registry should be added using both options to enable search, and, if there is a blacklist, to perform other operations, such as pulling images.
					For testing purposes, an example is shown on how to add a localhost insecure registry.
				
Procedure
- Modify - /etc/containers/registries.confconfiguration file to add the localhost insecure registry:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Prior to 3.6, modify the - /etc/sysconfig/dockerconfiguration file to add the localhost:- ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com --add-registry=docker.io --add-registry=localhost:5000" INSECURE_REGISTRY="--insecure-registry=localhost:5000" BLOCK_REGISTRY='--block-registry=all' - ADD_REGISTRY="--add-registry=registry.access.redhat.com --add-registry=my.registry.example.com --add-registry=docker.io --add-registry=localhost:5000" INSECURE_REGISTRY="--insecure-registry=localhost:5000" BLOCK_REGISTRY='--block-registry=all'- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Restart the - dockerdaemon to use the registry:- sudo systemctl restart docker.service - $ sudo systemctl restart docker.service- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - Restarting the - dockerdaemon causes the- dockercontainers to be restarted.
- Run a Docker registry pod at - localhost:- sudo docker run -p 5000:5000 registry:2 - $ sudo docker run -p 5000:5000 registry:2- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Pull an image: - sudo docker pull openshift/hello-openshift - $ sudo docker pull openshift/hello-openshift- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Tag the image: - sudo docker tag docker.io/openshift/hello-openshift:latest localhost:5000/hello-openshift-local:latest - $ sudo docker tag docker.io/openshift/hello-openshift:latest localhost:5000/hello-openshift-local:latest- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Push the image to the local registry: - sudo docker push localhost:5000/hello-openshift-local:latest - $ sudo docker push localhost:5000/hello-openshift-local:latest- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Using the Ansible installer, this can be configured using the - openshift_docker_additional_registries,- openshift_docker_blocked_registries, and- openshift_docker_insecure_registriesvariables in the- Ansiblehosts file:- openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com,localhost:5000 openshift_docker_insecure_registries=localhost:5000 openshift_docker_blocked_registries=all - openshift_docker_additional_registries=registry.access.redhat.com,my.registry.example.com,localhost:5000 openshift_docker_insecure_registries=localhost:5000 openshift_docker_blocked_registries=all- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- You can also set the - openshift_docker_insecure_registriesvariable to the IP address of the host.- 0.0.0.0/0is not a valid setting.
7.3.5. Authenticated registries
					Using authenticated registries with docker requires the docker daemon to log in to the registry. With OpenShift Container Platform, a different set of steps must be performed, because the users can not run docker login commands on the host. Authenticated registries can be used to limit the images users can pull or who can access the external registries.
				
					If an external docker registry requires authentication, create a special secret in the project that uses that registry and then use that secret to perform the docker operations.
				
Procedure
- Create a - dockercfgsecret in the project where the user is going to log in to the- dockerregistry:- oc project <my_project> oc create secret docker-registry <my_registry> --docker-server=<my.registry.example.com> --docker-username=<username> --docker-password=<my_password> --docker-email=<me@example.com> - $ oc project <my_project> $ oc create secret docker-registry <my_registry> --docker-server=<my.registry.example.com> --docker-username=<username> --docker-password=<my_password> --docker-email=<me@example.com>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- If a - .dockercfgfile exists, create the secret using the- occommand:- oc create secret generic <my_registry> --from-file=.dockercfg=<path/to/.dockercfg> --type=kubernetes.io/dockercfg - $ oc create secret generic <my_registry> --from-file=.dockercfg=<path/to/.dockercfg> --type=kubernetes.io/dockercfg- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Populate the - $HOME/.docker/config.jsonfile:- oc create secret generic <my_registry> --from-file=.dockerconfigjson=<path/to/.dockercfg> --type=kubernetes.io/dockerconfigjson - $ oc create secret generic <my_registry> --from-file=.dockerconfigjson=<path/to/.dockercfg> --type=kubernetes.io/dockerconfigjson- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Use the - dockercfgsecret to pull images from the authenticated registry by linking the secret to the service account performing the pull operations. The default service account to pull images is named- default:- oc secrets link default <my_registry> --for=pull - $ oc secrets link default <my_registry> --for=pull- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- For pushing images using the S2I feature, the - dockercfgsecret is mounted in the S2I pod, so it needs to be linked to the proper service account that performs the build. The default service account used to build images is named- builder.- oc secrets link builder <my_registry> - $ oc secrets link builder <my_registry>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- In the - buildconfig, the secret should be specified for push or pull operations:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- If the external registry delegates authentication to external services, create both - dockercfgsecrets: the registry one using the registry URL and the external authentication system using its own URL. Both secrets should be added to the service accounts.- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
7.3.6. ImagePolicy admission plug-in
					An admission control plug-in intercepts requests to the API, and performs checks depending on the configured rules and allows or denies certain actions based on those rules. OpenShift Container Platform can limit the allowed images running in the environment using the ImagePolicy admission plug-in where it can control:
				
- The source of images: which registries can be used to pull images
- Image resolution: force pods to run with immutable digests to ensure the image does not change due to a re-tag
- Container image label restrictions: force an image to have or not have particular labels
- Image annotation restrictions: force an image in the integrated container registry to have or not have particular annotations
						ImagePolicy admission plug-in is currently considered beta.
					
Procedure
- If the - ImagePolicyplug-in is enabled, it needs to be modified to allow the external registries to be used by modifying the- /etc/origin/master/master-config.yamlfile on every master node:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Note- Enabling - ImagePolicyrequires users to specify the registry when deploying an application like- oc new-app docker.io/kubernetes/guestbookinstead- oc new-app kubernetes/guestbook, otherwise it fails.
- To enable the admission plug-ins at installation time, the - openshift_master_admission_plugin_configvariable can be used with a- jsonformatted string including all the- pluginConfigconfiguration:- openshift_master_admission_plugin_config={"openshift.io/ImagePolicy":{"configuration":{"kind":"ImagePolicyConfig","apiVersion":"v1","executionRules":[{"name":"allow-images-from-other-registries","onResources":[{"resource":"pods"},{"resource":"builds"}],"matchRegistries":["docker.io","*my.registry.example.com*","registry.access.redhat.com"]}]}}}- openshift_master_admission_plugin_config={"openshift.io/ImagePolicy":{"configuration":{"kind":"ImagePolicyConfig","apiVersion":"v1","executionRules":[{"name":"allow-images-from-other-registries","onResources":[{"resource":"pods"},{"resource":"builds"}],"matchRegistries":["docker.io","*my.registry.example.com*","registry.access.redhat.com"]}]}}}- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Warning- There is a current issue to be fixed in OpenShift Container Platform 3.6.1 where - ImagePolicypods can not be deployed using default templates, and give the following error message- Failed create | Error creating: Pod "" is invalid: spec.containers[0].\image: Forbidden: this image is prohibited by policy.- See the Image Policy is not working as expected Red Hat Knowledgebase article for a workaround. 
7.3.7. Import images from external registries
					Application developers can import images to create imagestreams using the oc import-image command, and OpenShift Container Platform can be configured to allow or deny image imports from external registries.
				
Procedure
- To configure the allowed registries where users can import images, add the following to the - /etc/origin/master/master-config.yamlfile:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- To import images from an external authenticated registry, create a secret within the desired project.
- Even if not recommended, if the external authenticated registry is insecure or the certificates can not be trusted, the - oc import-imagecommand can be used with the- --insecure=trueoption.- If the external authenticated registry is secure, the registry certificate should be trusted in the master hosts as they run the registry import controller as: - Copy the certificate in the - /etc/pki/ca-trust/source/anchors/:- sudo cp <my.registry.example.com.crt> /etc/pki/ca-trust/source/anchors/<my.registry.example.com.crt> - $ sudo cp <my.registry.example.com.crt> /etc/pki/ca-trust/source/anchors/<my.registry.example.com.crt>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Run - update-ca-trustcommand:- sudo update-ca-trust - $ sudo update-ca-trust- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Restart the master services on all the master hosts: - sudo systemctl restart atomic-openshift-master-api sudo systemctl restart atomic-openshift-master-controllers - $ sudo systemctl restart atomic-openshift-master-api $ sudo systemctl restart atomic-openshift-master-controllers- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- The certificate for the external registry should be trusted in the OpenShift Container Platform registry: - for i in pem openssl java; do oc create configmap ca-trust-extracted-${i} --from-file /etc/pki/ca-trust/extracted/${i} oc set volume dc/docker-registry --add -m /etc/pki/ca-trust/extracted/${i} --configmap-name=ca-trust-extracted-${i} --name ca-trust-extracted-${i} done- $ for i in pem openssl java; do oc create configmap ca-trust-extracted-${i} --from-file /etc/pki/ca-trust/extracted/${i} oc set volume dc/docker-registry --add -m /etc/pki/ca-trust/extracted/${i} --configmap-name=ca-trust-extracted-${i} --name ca-trust-extracted-${i} done- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow Warning- There is no official procedure currently for adding the certificate to the registry pod, but the above workaround can be used. - This workaround creates - configmapswith all the trusted certificates from the system running those commands, so the recommendation is to run it from a clean system where just the required certificates are trusted.
- Alternatively, modify the registry image in order to trust the proper certificates rebuilding the image using a - Dockerfileas:- FROM registry.access.redhat.com/openshift3/ose-docker-registry:v3.6 ADD <my.registry.example.com.crt> /etc/pki/ca-trust/source/anchors/ USER 0 RUN update-ca-trust extract USER 1001 - FROM registry.access.redhat.com/openshift3/ose-docker-registry:v3.6 ADD <my.registry.example.com.crt> /etc/pki/ca-trust/source/anchors/ USER 0 RUN update-ca-trust extract USER 1001- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Rebuild the image, push it to a - dockerregistry, and use that image as- spec.template.spec.containers["name":"registry"].imagein the registry- deploymentconfig:- oc patch dc docker-registry -p '{"spec":{"template":{"spec":{"containers":[{"name":"registry","image":"*myregistry.example.com/openshift3/ose-docker-registry:latest*"}]}}}}'- $ oc patch dc docker-registry -p '{"spec":{"template":{"spec":{"containers":[{"name":"registry","image":"*myregistry.example.com/openshift3/ose-docker-registry:latest*"}]}}}}'- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
						To add the imagePolicyConfig configuration at installation, the openshift_master_image_policy_config variable can be used with a json formatted string including all the imagePolicyConfig configuration, like:
					
openshift_master_image_policy_config={"imagePolicyConfig":{"allowedRegistriesForImport":[{"domainName":"docker.io"},{"domainName":"\*.docker.io"},{"domainName":"*.redhat.com"},{"domainName":"*my.registry.example.com*"}]}}
openshift_master_image_policy_config={"imagePolicyConfig":{"allowedRegistriesForImport":[{"domainName":"docker.io"},{"domainName":"\*.docker.io"},{"domainName":"*.redhat.com"},{"domainName":"*my.registry.example.com*"}]}}
					For more information about the ImagePolicy, see the ImagePolicy admission plug-in section.
				
7.3.8. OpenShift Container Platform registry integration
You can install OpenShift Container Platform as a stand-alone container registry to provide only the registry capabilities, but with the advantages of running in an OpenShift Container Platform platform.
For more information about the OpenShift Container Platform registry, see Installing a Stand-alone Deployment of OpenShift Container Registry.
To integrate the OpenShift Container Platform registry, all previous sections apply. From the OpenShift Container Platform point of view, it is treated as an external registry, but there are some extra tasks that need to be performed, because it is a multi-tenant registry and the authorization model from OpenShift Container Platform applies so when a new project is created, the registry does not create a project within its environment as it is independent.
7.3.8.1. Connect the registry project with the cluster
						As the registry is a full OpenShift Container Platform environment with a registry pod and a web interface, the process to create a new project in the registry is performed using the oc new-project or oc create command line or via the web interface.
					
						Once the project has been created, the usual service accounts (builder, default, and deployer) are created automatically, as well as the project administrator user is granted permissions. Different users can be authorized to push/pull images as well as "anonymous" users.
					
There can be several use cases, such as allowing all the users to pull images from this new project within the registry, but if you want to have a 1:1 project relationship between OpenShift Container Platform and the registry, where the users can push and pull images from that specific project, some steps are required.
The registry web console shows a token to be used for pull/push operations, but the token showed there is a session token, so it expires. Creating a service account with specific permissions allows the administrator to limit the permissions for the service account, so that, for example, different service accounts can be used for push or pull images. Then, a user does not have to configure for token expiration, secret recreation, and other tasks, as the service account tokens will not expire.
Procedure
- Create a new project: - oc new-project <my_project> - $ oc new-project <my_project>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Create a registry project: - oc new-project <registry_project> - $ oc new-project <registry_project>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Create a service account in the registry project: - oc create serviceaccount <my_serviceaccount> -n <registry_project> - $ oc create serviceaccount <my_serviceaccount> -n <registry_project>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Give permissions to push and pull images using the - registry-editorrole:- oc adm policy add-role-to-user registry-editor -z <my_serviceaccount> -n <registry_project> - $ oc adm policy add-role-to-user registry-editor -z <my_serviceaccount> -n <registry_project>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow - If only pull permissions are required, the - registry-viewerrole can be used.
- Get the service account token: - TOKEN=$(oc sa get-token <my_serviceaccount> -n <registry_project>) - $ TOKEN=$(oc sa get-token <my_serviceaccount> -n <registry_project>)- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Use the token as the password to create a - dockercfgsecret:- oc create secret docker-registry <my_registry> \ --docker-server=<myregistry.example.com> --docker-username=<notused> --docker-password=${TOKEN} --docker-email=<me@example.com>- $ oc create secret docker-registry <my_registry> \ --docker-server=<myregistry.example.com> --docker-username=<notused> --docker-password=${TOKEN} --docker-email=<me@example.com>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- Use the - dockercfgsecret to pull images from the registry by linking the secret to the service account performing the pull operations. The default service account to pull images is named- default:- oc secrets link default <my_registry> --for=pull - $ oc secrets link default <my_registry> --for=pull- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- For pushing images using the S2I feature, the - dockercfgsecret is mounted in the S2I pod, so it needs to be linked to the proper service account that performs the build. The default service account used to build images is named- builder:- oc secrets link builder <my_registry> - $ oc secrets link builder <my_registry>- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow 
- In the - buildconfig, the secret should be specified for push or pull operations:- Copy to Clipboard Copied! - Toggle word wrap Toggle overflow