Red Hat Enterprise Linux (RHEL) System Roles
RHEL System Roles Overview
Red Hat Enterprise Linux (RHEL) 7.4 introduced RHEL System Roles as a collection of Ansible roles and modules that provide a stable and consistent configuration interface to remotely manage RHEL 6.10 and later versions of Red Hat Enterprise Linux. The effort is based on development of the Linux System Roles upstream project. The following roles are provided and supported as follows:
| Fully Supported | Technology Preview |
|---|---|
| kdump | postfix |
| network | |
| selinux | |
| timesync |
Roles in Technology Preview status are tested as stable but the interface (role inputs) may receive future updates that could be incompatible with the current state.
The RHEL System Roles are provided in the RHEL Extras channel.
The Ansible Engine product channel is provided as a convenience with the Red Hat Enterprise Linux subscription as an unsupported dependency for the implementation of RHEL System Roles. Support of Ansible Engine provided by the RHEL subscription is limited to the context of, and modules used by, the RHEL System Roles.
- Note: Previously, the ansible package was provided in the Extras channel. This version has been deprecated and will no longer receive updates. It is recommended to either uninstall this version and its dependencies, or enable the Ansible Engine channel in order to receive errata updates. More information can be found in the article Ansible deprecated in the Extras channel.
A full support subscription is available for Ansible Engine and Ansible Tower which are also able to use the RHEL System Roles. Additional information can be found at Top Support Policies for Red Hat Ansible Automation.
Typically Ansible Engine and the RHEL System Roles only need to be installed on a single, or few, Control node(s) which can then be used to manage or configure client nodes. While the roles will likely work with earlier versions, compatibility is only tested against RHEL 6.10 and later clients.
Getting Started
Installing RHEL System Roles and Ansible
The rhel-system-roles and ansible RPM packages are provided in the RHEL Extras and Ansible Engine channels respectively.
-
Use subscription-manager to list the Ansible Engine channels available. Note that the generic "2" channel will always provide the latest release of the 2.X stream as opposed to configuring a more specific version such as 2.5.
# subscription-manager refresh # subscription-manager repos --list | grep ansible -
To persistently enable the Extras channel and install using Red Hat Subscription Manager (Server is used in this example):
# subscription-manager refresh # subscription-manager repos --enable=rhel-7-server-extras-rpms --enable=rhel-7-server-ansible-2-rpms # yum install rhel-system-roles ansible -
To temporarily enable the Extras and Ansible Engine channels and install:
# subscription-manager refresh # yum --enablerepo=rhel-7-server-extras-rpms --enablerepo=rhel-7-server-ansible-2-rpms \ install rhel-system-roles ansible
Documentation
The rhel-system-roles package will install by default to the following locations where SUBSYSTEM is the name of the subsystem that contains the individual role manages. Examples may include network, timesync, or other subsystems as they become supported. Each subsystem role will include a README file which documents how to use the role and supported parameter values, as well as the matching README in the linux-system-roles Ansible Galaxy landing space.
-
Documentation
/usr/share/doc/rhel-system-roles-<version>/SUBSYSTEM/ -
Ansible Roles
/usr/share/ansible/roles/rhel-system-roles.SUBSYSTEM/
Example usage of the rhel-system-roles.network role
This example assumes the following
- Generally, Ansible is not installed on every system, but rather on a single system designated as the Ansible management or control node who's purpose is to manage other systems via Ansible.
- This example is executed from a RHEL 7.5 system used as the Ansible control node.
- A target, or client test system with a hostname of rhel7.5-test
- rhel7.5-test has a primary network interface to access (eth0), and a secondary interface for this example (eth1).
- Either the rhel7.5-test FQDN or IP Address has been added to the Ansible Inventory file /etc/ansible/hosts on the control node.
- The control node user ID running the test playbook has ssh access to, and
sudoability on rhel7.5-test. Alternatively, the-uoption can be used to specify a user which does have this ability. - For further details, see the Ansible Getting Started or Quick Start Video at http://docs.ansible.com/ for further details on how to use Ansible.
-
Using a text editor, create a file containing contents similar to the following:
$ vim example-network-playbook.yml --- - hosts: rhel7.5-test vars: network_connections: - name: DBnic state: up type: ethernet interface_name: eth1 autoconnect: yes ip: dhcp4: yes auto6: no roles: - role: rhel-system-roles.network -
Test that we have access to the machine. If not, refer to the Ansible documentation on how to enable Ansible to access a remote system.
$ ansible -m ping rhel7.5-test rhel7.5-test | SUCCESS => { "changed": false, "ping": "pong" } -
Query the Ansible Facts to see the guests network configuration.
$ ansible rhel7.5-test -m setup -a 'gather_subset=network filter=ansible_interfaces' rhel7.5-test | SUCCESS => { "ansible_facts": { "ansible_interfaces": [ "lo", "eth1", "eth0" ] }, "changed": false } -
Query the Ansible Facts to see the characteristics of eth1
$ ansible rhel7.5-test -m setup -a 'gather_subset=network filter=ansible_eth1' rhel7.5-test | SUCCESS => { "ansible_facts": { "ansible_eth1": { "active": true, "device": "eth1", "features": { "busy_poll": "off [fixed]", "fcoe_mtu": "off [fixed]", "generic_receive_offload": "on", "generic_segmentation_offload": "on", "highdma": "on [fixed]", "hw_tc_offload": "off [fixed]", "l2_fwd_offload": "off [fixed]", "large_receive_offload": "off [fixed]", "loopback": "off [fixed]", "netns_local": "off [fixed]", "ntuple_filters": "off [fixed]", "receive_hashing": "off [fixed]", "rx_all": "off [fixed]", "rx_checksumming": "on [fixed]", "rx_fcs": "off [fixed]", "rx_vlan_filter": "on [fixed]", "rx_vlan_offload": "off [fixed]", "rx_vlan_stag_filter": "off [fixed]", "rx_vlan_stag_hw_parse": "off [fixed]", "scatter_gather": "on", "tcp_segmentation_offload": "on", "tx_checksum_fcoe_crc": "off [fixed]", "tx_checksum_ip_generic": "on", "tx_checksum_ipv4": "off [fixed]", "tx_checksum_ipv6": "off [fixed]", "tx_checksum_sctp": "off [fixed]", "tx_checksumming": "on", "tx_fcoe_segmentation": "off [fixed]", "tx_gre_segmentation": "off [fixed]", "tx_gso_robust": "off [fixed]", "tx_ipip_segmentation": "off [fixed]", "tx_lockless": "off [fixed]", "tx_mpls_segmentation": "off [fixed]", "tx_nocache_copy": "off", "tx_scatter_gather": "on", "tx_scatter_gather_fraglist": "off [fixed]", "tx_sctp_segmentation": "off [fixed]", "tx_sit_segmentation": "off [fixed]", "tx_tcp6_segmentation": "on", "tx_tcp_ecn_segmentation": "on", "tx_tcp_segmentation": "on", "tx_udp_tnl_segmentation": "off [fixed]", "tx_vlan_offload": "off [fixed]", "tx_vlan_stag_hw_insert": "off [fixed]", "udp_fragmentation_offload": "on", "vlan_challenged": "off [fixed]" }, "macaddress": "52:54:00:e1:c2:4c", "module": "virtio_net", "mtu": 1500, "pciid": "virtio4", "promisc": false, "type": "ether" } }, "changed": false } -
Execute your example playbook. Note: You may safely ignore the warning message for now that the “wait for activation” feature is not yet implemented.
$ ansible-playbook -l rhel7.5-test example-network-playbook.yml PLAY [rhel7.5-test] ********************************************************************* TASK [Gathering Facts] ********************************************************* ok: [rhel7.5-test] TASK [rhel-system-roles.network : Check which services are running] ************ ok: [rhel7.5-test] TASK [rhel-system-roles.network : Check which packages are installed] ********** ok: [rhel7.5-test] TASK [rhel-system-roles.network : Install packages] **************************** skipping: [rhel7.5-test] TASK [rhel-system-roles.network : Enable network service] ********************** ok: [rhel7.5-test] TASK [rhel-system-roles.network : Print network provider] ********************** ok: [rhel7.5-test] => { "msg": "Using network provider: nm" } TASK [rhel-system-roles.network : Configure networking connection profiles] **** [WARNING]: [003] <info> #0, state:up persistent_state:present, 'DBnic': add connection DBnic, b62a7ea6-f1a4-408a-843e-ea292aa58b44 [WARNING]: [004] <info> #0, state:up persistent_state:present, 'DBnic': up connection DBnic, b62a7ea6-f1a4-408a-843e-ea292aa58b44 (is-modified) changed: [rhel7.5-test] TASK [rhel-system-roles.network : Re-test connectivity] ************************ ok: [rhel7.5-test] PLAY RECAP ********************************************************************* rhel7.5-test : ok=7 changed=1 unreachable=0 failed=0 -
Query again to see that eth1 is now online and has a IP Address assigned.
$ ansible rhel7.5-test -m setup -a 'gather_subset=network filter=ansible_eth1' rhel7.5-test | SUCCESS => { "ansible_facts": { "ansible_eth1": { "active": true, "device": "eth1", "features": { "busy_poll": "off [fixed]", "fcoe_mtu": "off [fixed]", "generic_receive_offload": "on", "generic_segmentation_offload": "on", "highdma": "on [fixed]", "hw_tc_offload": "off [fixed]", "l2_fwd_offload": "off [fixed]", "large_receive_offload": "off [fixed]", "loopback": "off [fixed]", "netns_local": "off [fixed]", "ntuple_filters": "off [fixed]", "receive_hashing": "off [fixed]", "rx_all": "off [fixed]", "rx_checksumming": "on [fixed]", "rx_fcs": "off [fixed]", "rx_vlan_filter": "on [fixed]", "rx_vlan_offload": "off [fixed]", "rx_vlan_stag_filter": "off [fixed]", "rx_vlan_stag_hw_parse": "off [fixed]", "scatter_gather": "on", "tcp_segmentation_offload": "on", "tx_checksum_fcoe_crc": "off [fixed]", "tx_checksum_ip_generic": "on", "tx_checksum_ipv4": "off [fixed]", "tx_checksum_ipv6": "off [fixed]", "tx_checksum_sctp": "off [fixed]", "tx_checksumming": "on", "tx_fcoe_segmentation": "off [fixed]", "tx_gre_segmentation": "off [fixed]", "tx_gso_robust": "off [fixed]", "tx_ipip_segmentation": "off [fixed]", "tx_lockless": "off [fixed]", "tx_mpls_segmentation": "off [fixed]", "tx_nocache_copy": "off", "tx_scatter_gather": "on", "tx_scatter_gather_fraglist": "off [fixed]", "tx_sctp_segmentation": "off [fixed]", "tx_sit_segmentation": "off [fixed]", "tx_tcp6_segmentation": "on", "tx_tcp_ecn_segmentation": "on", "tx_tcp_segmentation": "on", "tx_udp_tnl_segmentation": "off [fixed]", "tx_vlan_offload": "off [fixed]", "tx_vlan_stag_hw_insert": "off [fixed]", "udp_fragmentation_offload": "on", "vlan_challenged": "off [fixed]" }, "ipv4": { "address": "192.168.122.216", "broadcast": "192.168.122.255", "netmask": "255.255.255.0", "network": "192.168.122.0" }, "ipv6": [ { "address": "fe80::5054:ff:fee1:c24c", "prefix": "64", "scope": "link" } ], "macaddress": "52:54:00:e1:c2:4c", "module": "virtio_net", "mtu": 1500, "pciid": "virtio4", "promisc": false, "type": "ether" } }, "changed": false }
More examples
The roles carry their own example playbooks under their respective documentation directories (see above).
2 Comments
This article needs an update as RHEL 7.4 is now out of beta and the rhel-server-roles packages are available in the following channel (not beta):
The rhel-7-server-ansible-2-rpms contains all of the last 5 releases (currently 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4 and 2.5.0 releases, as of 2018 April). In most cases, the supporting packages are several releases behind what is available on extras and epel.
What is the value in maintaining all of these version specific channels? Administration should not need to know the release levels to enable, but rather select a general application set, and pick "latest", which is the entire point of ansible. This version specific channel idea is the exact opposite of what the product itself is intending to promote.