Just recently my colleague Andrew Nelson (@vmwnelson) posted an article on setting up Ansible on the Nutanix platform. I am also using Ansible to develop playbooks and the like to deploy the ELK stack components (Elasticsearch-Logstash-Kibana) on a block here at Nutanix. My initial aim is to setup a single index in an Elasticsearch (single node for now) cluster and use Logstash to pipe in data to be indexed. On top of that I intend to use Kibana and the Marvel plugin to measure at which point my index begins to struggle (based on stuff like OS level resource consumption, etc) as viewed from Marvel.
From a virtual machine perspective I have a Fedora 22 based gold image. From this base image I clone one VM to be the Ansible master that I will run playbooks (orchestration) from, and another VM which I will deploy my ELK stack to. This second “target” VM has had 7 vDisks added to it. The idea here being that Elasticsearch (ES) can use a comma separated list of vDisks (in my case I created them as six Linear LVM volumes). These are written to in a round robin fashion by ES and so the data gets “striped”. Nutanix vDisks are already redundant so we are getting a kind of RAID 10 for free! Here’s how my disk layout looks once configured and mounted (I am using XFS as my filesystem) on the target VM:
[root@elkhost01 ~]# df -h /dev/mapper/esdata05-esdata05 200G 271M 200G 1% /esdata/data05 /dev/mapper/esdata03-esdata03 200G 291M 200G 1% /esdata/data03 /dev/mapper/esdata04-esdata04 200G 273M 200G 1% /esdata/data04 /dev/mapper/esdata02-esdata02 200G 271M 200G 1% /esdata/data02 /dev/mapper/esdata06-esdata06 200G 291M 200G 1% /esdata/data06 /dev/mapper/eslog-eslog 100G 150M 100G 1% /var/log/elasticsearch /dev/mapper/esdata01-esdata01 200G 279M 200G 1% /esdata/data01 and [root@elkhost01 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert esdata01 esdata01 -wi-ao---- 200.00g esdata02 esdata02 -wi-ao---- 200.00g esdata03 esdata03 -wi-ao---- 200.00g esdata04 esdata04 -wi-ao---- 200.00g esdata05 esdata05 -wi-ao---- 200.00g esdata06 esdata06 -wi-ao---- 200.00g eslog eslog -wi-ao---- 100.00g
The next step is to install and configure Ansible. First off, configure an ansible user on both the orchestration host and target host and sync ssh keys between the two – (there’s a module that does ssh key exchange in Ansible and I will cover that at some stage) – like so:
on both VMs : useradd ansible passwd ansible # generate pub and priv keys .... ssh-keygen -t rsa If using strictmodes (default) in sshd_config file then ensure correct perms on .ssh directory and files chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys [ansible@elkhost01 ~]$ ls -l ~/.ssh total 12 -rw-------. 1 ansible ansible 404 Oct 1 13:38 authorized_keys -rw-------. 1 ansible ansible 1675 Oct 1 13:31 id_rsa -rw-------. 1 ansible ansible 402 Oct 1 13:31 id_rsa.pub Exchange public keys (copy into remote hosts authorized_keys file) for passwordless access [ansible@ansible-host01 ~]$ ssh-copy-id -i ~/.ssh/id_rsa.pub 10.68.64.117 /bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed /bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys ansible@10.68.64.126's password: Number of key(s) added: 1 Now try logging into the machine, with: "ssh '10.68.64.117'" and check to make sure that only the key(s) you wanted were added. [ansible@ansible-host01 ~]$ [ansible@ansible-host01 ~]$ ssh 10.68.64.117 Last login: Thu Oct 1 13:38:35 2015 from 10.68.64.113 [ansible@elkhost01 ~]$
Once you have passwordless ssh configured between your hosts – go ahead and install Ansible on the orchestration host:
# yum install ansible -y
Once installed, there are a few post install steps and tests to make sure that Ansible is working. First off set up a Ansible hosts inventory file that will eventually contain all the hostnames broken out by deployment type. The default location for this file is /etc/ansible/hosts. In this instance I have chosen to specify a non standard name/location in order keep my hosts file within my proposed playbook.
[ansible@ansible-host01 elk]$ pwd /home/ansible/elk [ansible@ansible-host01 elk]$ cat production # file: production [elastic-hosts] 10.68.64.117 [kibana-hosts] 10.68.64.117 [nginx-hosts] 10.68.64.126
And if the passwordless ssh setup is correct – we can test as follows :
[ansible@ansible-host01 elk]$ ansible all -m ping
10.68.64.117 | success >> {
"changed": false,
"ping": "pong"
}
Ansible machine configuration is done via playbooks, which are based on YAML syntax. There’s a great best practice guide here. I have followed that same best practice guide on playbook directory layout below …
elk ├── elastic.yml ├── group_vars ├── host_vars ├── kibana.yml ├── production ├── roles │ ├── common │ │ ├── files │ │ ├── handlers │ │ ├── tasks │ │ │ └── main.yml │ │ ├── templates │ │ └── vars │ │ └── main.yml │ ├── elastic │ │ ├── files │ │ │ └── elasticsearch.repo │ │ ├── handlers │ │ │ └── main.yml │ │ ├── tasks │ │ │ └── main.yml │ │ ├── templates │ │ │ ├── elasticsearch.default.j2 │ │ │ ├── elasticsearch.in.sh.j2 │ │ │ └── elasticsearch.yml.j2 │ │ └── vars │ │ └── main.yml │ └-- kibana │ ├── files │ ├── handlers │ │ └── main.yml │ ├── tasks │ │ └── main.yml │ ├── templates │ │ └── kibana4.service.j2 │ └── vars │ └── main.yml ├── site.yml
I am going to cover the individual roles for elasticsearch, logstash and kibana in subsequent posts. For now there’s a main site wide playbook :
[ansible@ansible-host01 elk]$ cat site.yml --- # file: site.yml - include: elastic.yml - include: kibana.yml - include: logstash.yml #- include: log-forwarder.yml #- include: redis.yml #- include: nginx.yml
Which is then broken up into individual service specific playbooks :
[ansible@ansible-host01 elk]$ cat elastic.yml --- #file: elastic.yml - hosts: elastic-hosts roles: - common - elastic [ansible@ansible-host01 elk]$ cat kibana.yml --- #file: kibana.yml - hosts: kibana-hosts roles: - kibana
I will discuss the individual roles and their associated tasks etc next time. For now this should be enough to get basic Ansible functionality going.
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