This is a simple role, based on DavidWittman/ansible-redis that installs redis.
- Requires Ansible 1.6.3+
- Compatible with most versions of Ubuntu/Debian and RHEL/CentOS
Below are a few example playbooks and configurations for deploying a variety of Redis architectures.
This role expects to be run as root or as a user with sudo privileges.
Deploying a single Redis server node is pretty trivial; just add the role to your playbook and go. Here's an example which we'll make a little more exciting by setting the bind address to 127.0.0.1:
---
- hosts: redis01.helabs.com
vars:
- redis_bind: 127.0.0.1
roles:
- helabs.redis
That's it! You'll now have a Redis server listening on 127.0.0.1 on
redis01.helabs.com. By default, the Redis binaries are installed under
/opt/redis, though this can be overridden by setting the redis_install_dir
variable.
Configuring replication in Redis is
accomplished by deploying multiple nodes, and setting the redis_slaveof
variable on the slave nodes, just as you would in the redis.conf. In the
example that follows, we'll deploy a Redis master with three slaves.
In this example, we're going to use groups to separate the master and slave nodes. Let's start with the inventory file:
[redis-master]
redis-master.helabs.com
[redis-slave]
redis-slave0[1:3].helabs.com
And here's the playbook:
---
- name: configure the master redis server
hosts: redis-master
roles:
- helabs.redis
- name: configure redis slaves
hosts: redis-slave
vars:
- redis_slaveof: redis-master.helabs.com 6379
roles:
- helabs.redis
redis_slaveof: "{{ hostvars['redis-master.helabs.com'].ansible_eth1.ipv4.address }} {{ redis_port }}"
Using Master-Slave replication is great for durability and distributing reads and writes, but not so much for high availability. If the master node fails, a slave must be manually promoted to master, and connections will need to be redirected to the new master. The solution for this problem is Redis Sentinel, a distributed system which uses Redis itself to communicate and handle automatic failover in a Redis cluster.
Sentinel itself uses the same redis-server binary that Redis uses, but runs with
the --sentinel
flag and with a different configuration file. All of this, of
course, is abstracted with this Ansible role, but it's still good to know.
To add a Sentinel node to an existing deployment, assign this same redis
role
\to it, and set the variable redis_sentinel
to True on that particular host.
[redis-master]
redis-master.helabs.com
[redis-slave]
redis-slave0[1:3].helabs.com
[redis-sentinel]
redis-sentinel0[1:3].helabs.com redis_sentinel=True
Above, we've added three more hosts in the redis-sentinel group (though this
group serves no purpose within the role, it's merely an identifier), and set the
redis_sentinel
variable inline within the inventory file.
Now, all we need to do is set the redis_sentinel_monitors
variable to define
the Redis masters which Sentinel should monitor. In this case, I'm going to do
this within the playbook:
- name: configure the master redis server
hosts: redis-master
roles:
- helabs.redis
- name: configure redis slaves
hosts: redis-slave
vars:
- redis_slaveof: redis-master.helabs.com 6379
roles:
- helabs.redis
- name: configure redis sentinel nodes
hosts: redis-sentinel
vars:
- redis_sentinel_monitors:
- name: master01
host: redis-master.helabs.com
port: 6379
roles:
- helabs.redis
This will configure the Sentinel nodes to monitor the master we created above
using the identifier master01
. By default, Sentinel will use a quorum of 2,
which means that at least 2 Sentinels must agree that a master is down in order
for a failover to take place. This value can be overridden by setting the
quorum
key within your monitor definition.
See the Sentinel docs for more details.
Along with the variables listed above, Sentinel has a number of its own
configurables just as Redis server does. These are prefixed with
redis_sentinel_
, and are enumerated in the Role Variables section below.
If the environment your server resides in does not allow downloads (i.e. if the machine is sitting in a dmz) set the variable redis_tarball
to the path of a locally downloaded tar.gz file to prevent a http download from redis.io.
For example (file was stored in same folder as the playbook that included the redis role):
vars:
- redis_version: 2.8.14
- redis_tarball: redis-2.8.14.tar.gz
In this case the source archive is copied towards the server over ssh rather than downloaded.
Here is a list of all the default variables for this role, which are also available in defaults/main.yml. One of these days I'll format these into a table or something.
---
## Installation options
redis_version: 2.8.9
redis_install_dir: /opt/redis
redis_user: redis
redis_group: "{{ redis_user }}"
redis_dir: /var/lib/redis/{{ redis_port }}
redis_download_url: "http://download.redis.io/releases/redis-{{ redis_version }}.tar.gz"
redis_tarball: false
# The open file limit for Redis/Sentinel
redis_nofile_limit: 16384
## Role options
# Configure Redis as a service
# This creates the init scripts for Redis and ensures the process is running
# Also applies for Redis Sentinel
redis_as_service: true
# Add local facts to /etc/ansible/facts.d for Redis
redis_local_facts: true
## Networking/connection options
redis_bind: 0.0.0.0
redis_port: 6379
redis_password: false
redis_tcp_backlog: 511
redis_tcp_keepalive: 0
# Max connected clients at a time
redis_maxclients: 10000
redis_timeout: 0
# Socket options
# Set socket_path to the desired path to the socket. E.g. /var/run/redis/{{ redis_port }}.sock
redis_socket_path: false
redis_socket_perm: 755
## Replication options
# Set slaveof just as you would in redis.conf. (e.g. "redis01 6379")
redis_slaveof: false
# Make slaves read-only. "yes" or "no"
redis_slave_read_only: "yes"
redis_slave_priority: 100
redis_repl_backlog_size: false
## Logging
redis_logfile: '""'
# Enable syslog. "yes" or "no"
redis_syslog_enabled: "yes"
redis_syslog_ident: redis_{{ redis_port }}
# Syslog facility. Must be USER or LOCAL0-LOCAL7
redis_syslog_facility: USER
## General configuration
redis_daemonize: "yes"
redis_pidfile: /var/run/redis/{{ redis_port }}.pid
# Number of databases to allow
redis_databases: 16
redis_loglevel: notice
# Log queries slower than this many milliseconds. -1 to disable
redis_slowlog_log_slower_than: 10000
# Maximum number of slow queries to save
redis_slowlog_max_len: 128
# Redis memory limit (e.g. 4294967296, 4096mb, 4gb)
redis_maxmemory: false
redis_maxmemory_policy: noeviction
redis_rename_commands: []
# How frequently to snapshot the database to disk
# e.g. "900 1" => 900 seconds if at least 1 key changed
redis_save:
- 900 1
- 300 10
- 60 10000
redis_appendonly: "no"
redis_appendfilename: "appendonly.aof"
redis_appendfsync: "everysec"
redis_no_appendfsync_on_rewrite: "no"
redis_auto_aof_rewrite_percentage: "100"
redis_auto_aof_rewrite_min_size: "64mb"
## Redis sentinel configs
# Set this to true on a host to configure it as a Sentinel
redis_sentinel: false
redis_sentinel_dir: /var/lib/redis/sentinel_{{ redis_sentinel_port }}
redis_sentinel_bind: 0.0.0.0
redis_sentinel_port: 26379
redis_sentinel_pidfile: /var/run/redis/sentinel_{{ redis_sentinel_port }}.pid
redis_sentinel_logfile: '""'
redis_sentinel_syslog_ident: sentinel_{{ redis_sentinel_port }}
redis_sentinel_monitors:
- name: master01
host: localhost
port: 6379
quorum: 2
auth_pass: ant1r3z
down_after_milliseconds: 30000
parallel_syncs: 1
failover_timeout: 180000
notification_script: false
client_reconfig_script: false
The following facts are accessible in your inventory or tasks outside of this role.
- `{{ ansible_local.redis.bind }}`
- `{{ ansible_local.redis.port }}`
- `{{ ansible_local.redis.sentinel_bind }}`
- `{{ ansible_local.redis.sentinel_port }}`
- `{{ ansible_local.redis.sentinel_monitors }}`
To disable these facts, set redis_local_facts
to a false value.