Services, Ports, Protocols#
Apache#
Apache serves the ICE ClusterWare ™ REST API via HTTP on port 80 using
the httpd systemd service aliased as
clusterware. HTTPS Encryption over port 443 can be enabled through
standard Apache and operating system procedures. Apache is Open
Source, and Penguin Computing contributes the REST API. The
log files are /var/log/clusterware/api_access_log and
/var/log/clusterware/api_error_log.
The ClusterWare GUI is also served through Apache from the
/var/www/clusterware/front/ directory.
Chrony#
Chrony is used to keep time synchronized across the cluster, including synchronization to upstream network time-servers and to all nodes within the cluster itself. In a cluster with multiple head nodes where no upstream time server is reachable, the head nodes select one head node as the time server and the remaining head nodes and other nodes within the cluster use that head node as the time source.
The systemd service name is chronyd and it uses port 123 for its time-keeping
communications and port 323 for receiving commands from the chronyc
management tool. This service is configured and restarted by the ClusterWare
service based on the cluster configuration. The configuration file is generated
from a template located at /opt/scyld/clusterware-chrony/chrony.conf.template.
It is common to configure the head node(s) to use an external time source and leave the compute node configuration as-is so that the compute nodes reference the head node as a time source. While not recommended, it is also possible to change the time source on compute nodes. If you do change the compute node time source, make sure the head nodes are synchronized to each other and to the compute nodes.
DHCP#
DHCP provides dynamic host configuration and is used when provisioning compute nodes. If you are using the ClusterWare software to provision compute nodes, you cannot disable or swap to a different DHCP service or server.
DHCP has a systemd service name clusterware-dhcpd and uses
port 68. The log file is var/log/clusterware/isc-dhcpd.log. This
service is configured, started, and stopped by the ClusterWare service based on
the cluster configuration. The configuration file is generated from a template
located at /opt/scyld/clusterware-iscdhcp/dhcpd.conf.template.
Important
Never directly try to control DHCP on a ClusterWare head node, it
will not work. Services that start with clusterware- are managed by the
ClusterWare service.
DNS#
DNS provides name- and ip-address-lookup services. Resolution of compute node
hostnames go through the DNS server. The ClusterWare software also provides DNS
name resolution using the cw-clusterctl hosts command and can add IP
addresses to name mappings as well as custom SRV records. For details, see
Node Name Resolution. If you are using Slurm with your compute nodes, DNS is also
used for Slurm-specific SRV records. The Slurm SRV records are used by compute
nodes to locate the Slurm controller.
While not recommended, it is possible to use an alternate DNS source. However, you will lose access to the DNS capabilities described. If you are using an alternate DNS source, make sure the compute node hostnames are resolvable.
DNS has a systemd service name clusterware-dnsmasq and uses port 53.
This service is configured, started, and stopped by the ClusterWare service
based on the clusterconfiguration. The configuration file is generated from a
template located at /opt/scyld/clusterware-dnsmasq/dnsmasq.conf.template.
Important
Never directly try to control DNS on a ClusterWare head node, it
will not work. Services that start with clusterware- are managed by the
ClusterWare service.
etcd#
The replicated configuration key/value store etcd
has the systemd service name clusterware-etcd.
Log files are found in /var/log/clusterware/.
etcd uses port 52380 to communicate with other head nodes.
Important
Never directly try to control etcd on a ClusterWare head node, it
will not work. Services that start with
clusterware- are managed by the ClusterWare service.
iSCSI#
iSCSI optionally serves root filesystems to compute nodes and uses
port 3260. Serving root file systems via iSCSI is configured by the
ClusterWare service using the targetcli command line tool.
OpenSSH#
OpenSSH provides services to remotely execute programs and to transfer files,
with a systemd service name sshd and using port 22.
Encryption is SSH.
The log file is /var/log/messages.
Telegraf / Telegraf-Relay / InfluxDB#
All head node and compute node performance data collected by telegraf is sent to a systemd service named telegraf-relay on one of the head nodes over HTTP(S). Telegraf-Relay replicates and relays this data to every other telegraf-relay over HTTPS. Each telegraf-relay finally sends the data to its locally hosted InfluxDB for storage.
TFTP#
The TFTP Server provides downloads for early iPXE boot files,
with a systemd service name xinetd and using port 69.
This service can be replaced by appropriate network card firmware.
The log file is /var/log/messages.