Specifying a custom Network Time Protocol (NTP) server

Allow access to Red Hat NTP servers or configure a custom Network Time Protocol (NTP) server for your hosts.

You can specify a custom NTP server for Red Hat CoreOS hosts only.

Specifying a custom NTP server for an unattached host

To configure your hosts to use a custom NTP server before you attach them to a location, edit the host script to include your custom NTP server information. This example uses a chrony NTP server.

Create a chrony.conf file similar to the following example.

pool time.adn.networklayer.com iburst

server time.adn.networklayer.com iburst minpoll 3 maxpoll 4

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Specify file containing keys for NTP authentication.
keyfile /etc/chrony.keys

# Get TAI-UTC offset and leap seconds from the system tz database.
leapsectz right/UTC

# Specify directory for log files.
logdir /var/log/chrony

Convert the content to base64.
```
cat chrony.conf | base64
```
Download the attach script for your location. For RHCOS hosts, the attach script is an ignition (.ign) script.
```
ibmcloud sat host attach --location LOCATION --operating-system RHCOS
```

Edit the script and add an entry to the storage.files array, where BASE64_ENCODED_CHRONY_FILE_DATA is the base 64 string from step 2.

{
  "overwrite": true,
  "path": "/etc/chrony.conf",
  "contents": {
    "source":"data:text/plain;base64,BASE64_ENCODED_CHRONY_FILE_DATA"
    },
    "mode": 420
 }

Save the script.
Validate the script.
```
cat IGNITION_FILE_PATH | jq -r
```

After your script is validated, you can attach the hosts to your location.

Specifying a custom NTP server for an attached host

You can configure a custom NTP server for your hosts after they are attached to the location.

Create a chrony.conf file similar to the following example.

pool time.adn.networklayer.com iburst

server time.adn.networklayer.com iburst minpoll 3 maxpoll 4

# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift

# Allow the system clock to be stepped in the first three updates
# if its offset is larger than 1 second.
makestep 1.0 3

# Enable kernel synchronization of the real-time clock (RTC).
rtcsync

# Specify file containing keys for NTP authentication.
keyfile /etc/chrony.keys

# Get TAI-UTC offset and leap seconds from the system tz database.
leapsectz right/UTC

# Specify directory for log files.
logdir /var/log/chrony

Log in to the host system.
Update the chrony.conf file for that host, where CHRONY_FILE_DATA is the name of the file you created in step 1. Do not convert this file into base64.
```
cat >"/etc/chrony.conf" <<EOF
CHRONY_FILE_DATA
EOF
systemctl restart chronyd
```

After you update the chrony.conf file, your host uses your custom NTP server.