Specifying a custom Network Time Protocol (NTP) server

Keeping time is an integral part of any system. You can choose to allow access to the Red Hat network time protocol (NTP) servers or you can configure access to a custom Network Time Protocol (NTP) server.

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 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.