| CHAKE(1) | CHAKE(1) |
chake - serverless configuration with chef
chake is a tool that helps you manage multiple hosts with, without the need for a chef server. Configuration is managed in a local directory, which should probably be under version control with git(1) or anything else. Configuration is usually deployed via rsync over SSH, and applied by invoking chef-solo(1) over SSH on each host.
$ chake init [create] nodes.yaml [ mkdir] nodes.d/ [create] config.rb [ mkdir] config/roles [ mkdir] cookbooks/basics/recipes/ [create] cookbooks/basics/recipes/default.rb [create] Rakefile
A brief explanation of the created files:
After the repository is created, you can call either chake or rake, as they are completely equivalent.
Just after you created your repository, the contents of nodes.yaml is the following:
host1.mycompany.com:
run_list:
- recipe[basics]
You can list your hosts with rake nodes:
$ rake nodes host1.mycompany.com ssh
To add more nodes, just append to nodes.yaml:
host1.mycompany.com:
run_list:
- recipe[basics] host2.mycompany.com:
run_list:
- recipes[basics]
And chake now knows about your new node:
$ rake nodes host1.mycompany.com ssh host2.mycompany.com ssh
Nodes have very few initial requirements to be managed with chake:
A note on password prompts: every time chake calls ssh on a node, you may be required to type in your password; every time chake calls sudo on the node, you may be require to type in your password. For managing one or two nodes this is probably fine, but for larger numbers of nodes it is not practical. To avoid password prompts, you can:
To check whether hosts are correcly configured, you can use the check task:
$ rake check
That will run the the sudo true command on each host. If that pass without you having to passwords, you are sure that
$ rake check
Note that by default all tasks that apply to all hosts will run in parallel, using rake’s support for multitasks. If for some reason you need to prevent that, you can pass -j1 (or --jobs=1`) in the rake invocation. Note that by default rake will only run N+4 tasks in parallel, where N is the number of cores on the machine you are running it. If you have more than N+4 hosts and want all of them to be handled in parallel, you might want o pass -j (or --jobs), without any number, as the last argument; with that rake will have no limit on the number of tasks to perform in parallel.
To apply the configuration to all nodes, run
$ rake converge
To apply the configuration to a single node, run
$ rake converge:$NODE
To apply a single recipe on all nodes, run
$ rake apply[myrecipe]
To apply a single recipe on a specific node, run
$ rake apply:$NODE[myrecipe]
If you don’t inform a recipe in the command line, you will be prompted for one.
To run a shell command on all nodes, run
$ rake run[command]
If the command you want to run contains spaces, or other characters that are special do the shell, you have to quote them.
To run a shell command on a specific node, run
$ rake run:$NODE[command]
If you don’t inform a command in the command line, you will be prompted for one.
To check the existing tasks, run
$ rake -T
Since chake is actually a wrapper for Chef Solo, you should read the [chef documentation]( ⟨URL: https://docs.chef.io/ ⟩). In special, look at the [Chef Solo Documentation]( ⟨URL: https://docs.chef.io/chef_solo.html ⟩).
When chake acts on a node for the first time, it has to bootstrap it. The bootstrapping process includes doing the following:
The keys in the hash that is represented in nodes.yaml is a node URL. All components of the URL but the hostname are optional, so just listing hostnames is the simplest form of specifying your nodes. Here are all the components of the node URLs:
[backend://][username@]hostname[:port][/path]
You can define rake tasks that will be executed before bootstrapping nodes, before uploading configuration management content to nodes, and before converging. To do this, you just need to enhance the corresponding tasks:
Example:
task :bootstrap_common do
sh './scripts/pre-bootstrap-checks' end
Any files ending matching .gpg and .asc will be decrypted with GnuPG before being sent to the node. You can use them to store passwords and other sensitive information (SSL keys, etc) in the repository together with the rest of the configuration.
If you need special SSH configuration parameters, you can create a file called .ssh_config (or whatever file name you have in the $CHAKE_SSH_CONFIG environment variable, see below for details) in at the root of your repository, and chake will use it when calling ssh.
To easily login to one of your host, just run rake login:$HOSTNAME. This will automatically use the repository-local SSH configuration as above so you don’t have to type -F .ssh_config all the time.
Some times, you will also want or need to prefix your SSH invocations with some prefix command in order to e.g. tunnel it through some central exit node. You can do this by setting $CHAKE_SSH_PREFIX on your environment. Example:
CHAKE_SSH_PREFIX=tsocks rake converge
The above will make all SSH invocations to all hosts be called as tsocks ssh [...]
If you want to manage your local workstation with chake, you can declare a local node like this in nodes.yaml:
local://thunderbolt:
run_list:
- role[workstation]
To apply the configuration to the local host, you can use the conventional rake converge:thunderbolt, or the special target rake local.
When converging all nodes, chake will skip nodes that are declared with the local:// backend and whose hostname does not match the hostname in the declaration. For example:
local://desktop:
run_list:
- role[workstation] local://laptop:
run_list:
- role[workstation]
When you run rake converge on desktop, laptop will be skipped, and vice-versa.
| 2018-04-14 |