Configuring Docker or System Docker


In RancherOS, you can configure System Docker and Docker daemons by using cloud-config.

Configuring Docker

In your cloud-config, Docker configuration is located under the rancher.docker key.

#cloud-config
rancher:
  docker:
    tls: true
    tls_args: [--tlsverify, --tlscacert=ca.pem, --tlscert=server-cert.pem, --tlskey=server-key.pem, '-H=0.0.0.0:2376']
    storage_driver: overlay

You can also customize Docker after it’s been started using ros config.

$ sudo ros config set rancher.docker.storage_driver overlay

User Docker settings

Many of the standard Docker daemon arguments can be placed under the rancher.docker key. The command needed to start the Docker daemon will be generated based on these arguments. The following arguments are currently supported.

Key Value
bridge String
config_file String
containerd String
debug Boolean
exec_root String
group String
graph String
host List
insecure_registry List
live_restore Boolean
log_driver String
log_opts Map where keys and values are strings
pid_file String
registry_mirror String
restart Boolean
selinux_enabled Boolean
storage_driver String
userland_proxy Boolean

In addition to the standard daemon arguments, there are a few fields specific to RancherOS.

Key Value Default Description
extra_args List of Strings [] Arbitrary daemon arguments, appended to the generated command
environment List of Strings []  
tls Boolean false When setting up TLS, this key needs to be set to true.
tls_args List of Strings (used only if tls: true) []  
server_key String (used only if tls: true) "" PEM encoded server TLS key.
server_cert String (used only if tls: true) "" PEM encoded server TLS certificate.
ca_key String (used only if tls: true) "" PEM encoded CA TLS key.
storage_context String console Specifies the name of the system container in whose context to run the Docker daemon process.

Configuring System Docker

In your cloud-config, System Docker configuration is located under the rancher.system_docker key.

#cloud-config
rancher:
  system_docker:
    storage_driver: overlay

System Docker settings

All daemon arguments shown in the first table are also available to System Docker. The following are also supported.

Key Value Default Description
extra_args List of Strings [] Arbitrary daemon arguments, appended to the generated command
environment List of Strings (optional) []  

Using a pull through registry mirror

There are 3 Docker engines that can be configured to use the pull-through Docker Hub registry mirror cache:

#cloud-config
rancher:
  bootstrap_docker:
    registry_mirror: "http://10.10.10.23:5555"
  docker:
    registry_mirror: "http://10.10.10.23:5555"
  system_docker:
    registry_mirror: "http://10.10.10.23:5555"

bootstrap_docker is used to prepare and initial network and pull any cloud-config options that can be used to configure the final network configuration and System-docker - its very unlikely to pull any images.

A successful pull through mirror cache request by System-docker looks like:

[[email protected] rancher]# system-docker pull alpine
Using default tag: latest
DEBU[0201] Calling GET /v1.23/info
> WARN[0201] Could not get operating system name: Error opening /usr/lib/os-release: open /usr/lib/os-release: no such file or directory
WARN[0201] Could not get operating system name: Error opening /usr/lib/os-release: open /usr/lib/os-release: no such file or directory
DEBU[0201] Calling POST /v1.23/images/create?fromImage=alpine%3Alatest
DEBU[0201] hostDir: /etc/docker/certs.d/10.10.10.23:5555
DEBU[0201] Trying to pull alpine from http://10.10.10.23:5555/ v2
DEBU[0204] Pulling ref from V2 registry: alpine:latest
DEBU[0204] pulling blob "sha256:2aecc7e1714b6fad58d13aedb0639011b37b86f743ba7b6a52d82bd03014b78e" latest: Pulling from library/alpine
DEBU[0204] Downloaded 2aecc7e1714b to tempfile /var/lib/system-docker/tmp/GetImageBlob281102233 2aecc7e1714b: Extracting  1.99 MB/1.99 MB
DEBU[0204] Untar time: 0.161064213s
DEBU[0204] Applied tar sha256:3fb66f713c9fa9debcdaa58bb9858bd04c17350d9614b7a250ec0ee527319e59 to 841c99a5995007d7a66b922be9bafdd38f8090af17295b4a44436ef433a2aecc7e1714b: Pull complete
Digest: sha256:0b94d1d1b5eb130dd0253374552445b39470653fb1a1ec2d81490948876e462c
Status: Downloaded newer image for alpine:latest