mirror of https://github.com/ceph/ceph-ansible.git
70 lines
4.4 KiB
Markdown
70 lines
4.4 KiB
Markdown
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# ceph-iscsi-ansible
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This project provides a mechanism to deploy iSCSI gateways in front of a ceph cluster using Ansible. The ansible playbooks
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provided rely upon configuration logic from the "ceph-iscsi-config" project. This separation provides independence to the
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configuration logic, potentially opening up the possibility for puppet/chef to create/manage ceph/iSCSI gateways in the
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same way.
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## Introduction
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At a high level, this project provides custom modules which are responsible for calling the configuration logic, together
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with the relevant playbooks. The project defines a new ceph-ansible role; ceph-iscsi-gw, together with two playbooks;
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- **ceph-iscsi-gw-yml** ... to define our change the gateway configuration based on group_vars/ceph-iscsi-gw.yml
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- **purge_gateways.yml** .. to destroy the LIO configuration, or the LIO and any associated rbd images.
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## Features
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The combination of the playbooks and the configuration logic deliver the following features;
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- confirms RHEL7.3 and aborts if necessary
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- ensures targetcli/device-mapper-multipath is installed (for rtslib support)
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- configures multipath.conf
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- creates rbd's if needed - at allocation time, each rbd is assigned an owner, which will become the preferred path
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- checks the size of the rbds at run time and expands if necessary
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- maps the rbd's to the host (gateway)
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- enables the rbdmap service to start on boot, and reconfigures the target service to be dependent on rbdmap
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- adds the rbd's to the /etc/ceph/rbdmap file ensuring the devices are automatically mapped following a gateway reboot
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- maps these rbds to LIO
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- once mapped, the alua preferred path state is set or cleared (supporting an active/passive topology)
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- creates an iscsi target - common iqn, and multiple tpg's
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- adds a portal ip based on a the provided IP addresses defined in the group vars to each tpg
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- enables the local tpg, other gateways are defined as disabled
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- adds all the mapped luns to ALL tpg's (ready for client assignment)
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- add clients to the active/enabled tpg, with/without CHAP
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- images mapped to clients can be added/removed by changing image_list and rerunning the playbook
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- clients can be removed using the state=absent variable and rerunning the playbook. At this point the entry can be
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removed from the group variables file
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- configuration can be wiped with the purge_gateway playbook
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- current state can be seen by looking at the configuration object (stored in the rbd pool)
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### Why RHEL 7.3?
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There are several system dependencies that are required to ensure the correct (i.e. don't eat my data!) behaviors when OSD connectivity
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or gateway nodes fail. RHEL 7.3 delivers the necessary kernel changes, and also provides an updated multipathd, enabling rbd images
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to be managed by multipathd.
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## Prerequisites
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* a working ceph cluster ( *rbd pool defined* )
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* a server/host with ceph-ansible installed and working
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* nodes intended to be gateways should be at least ceph clients, with the ability to create and map rbd images
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## Testing So far
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The solution has been tested on a collocated cluster where the osd/mons and gateways all reside on the same node.
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## Quick Start
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### Prepare the iSCSI Gateway Nodes
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1. install the ceph-iscsi-config package on the nodes, intended to be gateways. NB. The playbook includes a check for the presence
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of this rpm (https://github.com/pcuzner/ceph-iscsi-config)
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### Install the ansible playbooks
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1. install the ceph-iscsi-ansible rpm from the packages directory on the node where you already have ceph-ansible installed.
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2. update /etc/ansible/hosts to include a host group (ceph-iscsi-gw) for the nodes that you want to become iscsi gateways
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3. make a copy of the group_vars/ceph-iscsi-gw.sample file called ceph-iscsi-gw, and update it to define the environment you want
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4. run the playbook
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```> ansible-playbook ceph-iscsi-gw.yml```
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## Purging the configuration
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As mentioned above, the project provides a purge-gateways.yml playbook which can remove the LIO configuration alone, or remove
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both LIO and all associated rbd images that have been declared in the group_vars/ceph-iscsi-gw file. The purge playbook will
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check for any active iscsi sessions, and abort if any are found.
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## Known Issues and Considerations
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1. the ceph cluster name is the default 'ceph', so the corresponding configuration file /etc/ceph/ceph.conf is assumed to be valid
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