modularitycontainers/chronyd repository overview

⁠chrony

Network Time Protocol Server Container

⁠Dependencies

To build the chrony container, some components are required that aren't in the Base Runtime image.

⁠Build Dependencies

• pps-tools

⁠How to build the container

docker build --tag=chrony .

⁠How to use the container

The chrony server uses a config file (/etc/chrony.conf:) on the host, this file needs to be created first. Example contents of /etc/chrony.conf, see 'man chrony.conf' for more options:

server 127.127.8.0 mode 2 # local radio clock
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 12 # local fallback clock

Command for running chrony docker container:

  # in privileged mode, try to avoid this:
  # docker run --privileged -v /etc/chrony.conf:/etc/ntp.conf:ro -d chrony
  # better solution with capabilities, needs docker-1.12:
  docker run --net=host --cap-add SYS_TIME -v /etc/chrony.conf:/etc/ntp.conf:ro -d $(IMAGE_NAME)

⁠How to test the chrony server

Commands for testing chrony docker container:

ntpq -c "host localhost -pn

replace localhost with container IP if required

⁠Running on OpenShift

This container requires root in order to run chronyd as chronyd checks for the user ID. It also requires the SYS_TIME capability. The required steps are:

oadm policy add-scc-to-user anyuid -z default
oc edit scc anyuid

An editor terminal will open after the last command. Search for

allowedCapabilities: null

and replace it with

allowedCapabilities:
- SYS_TIME

and

defaultAddCapabilities: null

with

defaultAddCapabilities:
- SYS_TIME

Save and exit the editor and then deploy the container.