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--- # Ansible .footnote[Tip: press `P` to view the presenter notes] ??? Presenter notes contain extra information which might be useful if you intend to use these slides for teaching. Press `P` again to switch presenter notes off --- ## Configuration Management - Manages the configuration of machines - Specifies what software is installed, how it is configured --- ### Why Configuration Management What happened: - Precisely what changes were made? - Did you write them down? - Can you reproduce them precisely for the next machine? What if: - ... your server dies? - ... your VM is accidentally deleted? - Can you recover? --- ### Why Configuration Management - Reproducibility - Ensure 1000s of machines are correctly configured - Easily recover from bad situations --- ### Ansible - Ansible is one of many tools (Chef, Puppet, Salt, etc) - It uses a 'push' model: SSH into machine and executes commands - Very popular - Many modules for common tasks like copying files or managing users or services. --- ## Important Terms --- ### Inventory File ```ini [webservers] 192.168.0.1 192.168.0.2 ansible_user=ubuntu [databases] db_1.example.org ansible_user=root ``` ??? Defines the systems (called "hosts") against which Ansible will work. The headings in square brackets are group names, used to select a set of systems on which Ansible should operate. It is possible to assign variables to hosts and groups to be used later in playbooks. --- ### Ansible Module and Tasks ```yaml --- - copy: src: foo.conf dest: /etc/foo.conf owner: foo group: foo mode: 0644 - package: name: ntpdate state: present ``` ??? Tasks are module invocations with their configuration. Here is an example of invoking the `copy` module and the package module. Copy copies a file from `src` on the local host to destination (the remote host) and sets some attributes about the file Next we see an example of the `package` module, a generic OS package manager. It ensures that for the package named `ntpdate`, its state is `present` (i.e. installed) --- ### Role .pull-left[ A collection of: - tasks - files - templates - variables - handlers ] .pull-right[ ``` . ├── defaults │ └── main.yml ├── handlers │ └── main.yml ├── meta │ └── main.yml ├── README.md ├── tasks │ ├── apache.yml │ ├── main.yml │ └── stratumN.yml ├── templates │ └── stratum1_squid.conf.j2 ├── tests │ ├── inventory │ └── test.yml └── vars └── main.yml ``` ] ??? **Tasks** will be executed which will usually include tasks to **copy** files from the `files` directory and **template** files from the `templates` directory over to the remote server. **variables** are defined for use in the templates and tasks, and **handlers** are used to automatically restart services when configuration changes. --- ### Playbook .pull-left[ - We define a playbook which has a name - And applies to some group of hosts - We specify some additional variables - And then invoke some roles ] .pull-right[ ```yaml - name: CVMFS hosts: all vars: cvmfs_role: client galaxy_cvmfs_repos_enabled: true roles: - geerlingguy.repo-epel - galaxyproject.cvmfs ``` ] --- ### Vault Allows encryption of files, can collaborate on Ansible playbooks without worrying about accidentally sharing secrets like passwords. ``` $ANSIBLE_VAULT;1.1;AES256 63333238633033313664633437316231323932326531386266636637353037313335613563663934 6639666536653631363739383639633165633337393334630a353233393938646539306362633738 61613439366435336230636561663864323765303663666239613430323534333665636665643964 6537376666323333660a663233343565393166373665366138306661343764623561343634656463 31636265303430623731643766346434323565663436626466353765393465376533376366356463 ``` --- ## Ansible Philosophies - Some people write a single playbook that completely manages a machine (installing everything on a brand new machine) - Other people write playbooks for a single task (e.g. upgrading software) - Which one depends on your use case. --- ## Ansible Galaxy - Public repository of roles - Many for common software deployment (nginx, apache, postgresql) - Different "Galaxy" than the bioinformatics tool server (but Ansible can be used to install that too!) --- ## Thank you! This material is the result of a collaborative work. Thanks to the [Galaxy Training Network](https://wiki.galaxyproject.org/Teach/GTN) and all the contributors!
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