Concepts

Why?

Getch is insipired by Hiera and copies the concept of a queryable hierarchical datastore. It is a purely server side implementation which uses HTTP to offer a queryable interface to hosts in your DataCenter (or anywhere else as long as you can establish a TCP connection).

The tool is meant to be used by organization who don't have a fully fledged configuration management system (like Chef, Puppet etc.) deployed but still want to benefit from a central hierarchical configuration store.

Additionally because everything is stored in a directory structure in plain text files you can manage the whole configuration hierarchy in the version control system of your choice (passwords can by stored in an encrypted format).

Concept

The idea is to build a directory tree structure representing the structure of your IT organization and services.

This structure can be queried with any HTTP client (be it a browser or a command-line tool like curl or wget). There is also a native command line client available called getchctl. Clients can query either for a single key in order to receive a single value or filenames in order to download complete files.

Getch reacts to queries by searching through its configured directory tree until it finds a directory with the same name that the querying host has. Starting from this directory it will scan all files downwards and upwards in the directory tree.

In case a single key was queried, all found files (on all levels of the tree in the path identifies with the hostname) will be scanned to see if any one contains the queried key. The corresponding value of the key is then returned as plain text inside the HTTP response body. The identified tree path is scanned bottom-up and therefore more concrete (lower level) values are preferred over more commonly defined (higher level) values.

In case a filename was queried Getch will scan all levels of the tree (again only the path to the querying hostname directory) in order to find a file with the same name. If it finds one it will send the file through an internal template engine before it is returned as a downloadable file back to the HTTP client. The templating engine will have all key=value pairs from all configuration files of all layers through the complete path of the hostname in its context. Effectively this way you can use configuration values from anywhere in the hierarchy as variables (referenced by their key) in configuration files that you store in Getch.

Find below a sample directory structure that Getch may work with. How you layout your hierarchy is completely up to you.

  .
  └── myorg/
      ├── departmentA/
      │   ├── common.properties
      │   ├── serviceA/
      │   │   ├── preprod/
      │   │   │   ├── app/
      │   │   │   │   └── hostname5/
      │   │   │   │       └── tomcat/
      │   │   │   │           ├── datasources.yaml
      │   │   │   │           └── instance.properties
      │   │   │   ├── db/
      │   │   │   │   └── hostname6/
      │   │   │   │       └── mysql/
      │   │   │   │           └── my.cnf
      │   │   │   └── web/
      │   │   │       └── hostname4/
      │   │   │           └── apache/
      │   │   │               └── webserver_details.properties
      │   │   ├── prod/
      │   │   │   ├── app/
      │   │   │   │   └── hostname2/
      │   │   │   │       ├── hostconfig.properties
      │   │   │   │       └── tomcat/
      │   │   │   │           ├── datasources.yaml
      │   │   │   │           └── instance.properties
      │   │   │   ├── db/
      │   │   │   │   └── hostname3/
      │   │   │   │       ├── hostconfig.properties
      │   │   │   │       └── mysql/
      │   │   │   │           └── my.cnf
      │   │   │   └── web/
      │   │   │       └── hostname1/
      │   │   │           ├── apache/
      │   │   │           │   └── webserver_details.properties
      │   │   │           └── hostconfig.properties
      │   │   ├── serviceA.yaml
      │   │   └── test/
      │   │       ├── ...
      │   └── serviceB/
      │       ├── preprod/
      │       │   ├── app/
      │       │   │   ├── hostname5/
      │       │   │   │   └── tomcat/
      │       │   │   │       ├── datasources.yaml
      │       │   │   │       └── instance.properties
      │       │   │   └── hostname14/
      │       │   │       └── tomcat/
      │       │   ├── db/
      │       │   │   ├── hostname6/
      │       │   │   │   └── mysql/
      │       │   │   │       └── my.cnf
      │       │   │   └── hostname15/
      │       │   │       └── mysql/
      │       │   └── web/
      │       │       ├── hostname4/
      │       │       │   └── apache/
      │       │       │       └── webserver_details.properties
      │       │       └── hostname13/
      │       │           └── apache/
      │       ├── prod/
      │       │   ├── app/
      │       │   │   ├── hostname2/
      │       │   │   │   ├── hostconfig.properties
      │       │   │   │   └── tomcat/
      │       │   │   │       ├── datasources.yaml
      │       │   │   │       └── instance.properties
      │       │   │   └── hostname11/
      │       │   │       └── tomcat/
      │       │   ├── db/
      │       │   │   ├── hostname3/
      │       │   │   │   ├── hostconfig.properties
      │       │   │   │   └── mysql/
      │       │   │   │       └── my.cnf
      │       │   │   └── hostname12/
      │       │   │       └── mysql/
      │       │   └── web/
      │       │       ├── hostname1/
      │       │       │   ├── apache/
      │       │       │   │   └── webserver_details.properties
      │       │       │   └── hostconfig.properties
      │       │       └── hostname10/
      │       │           └── apache/
      │       ├── serviceB.yaml
      │       └── test/
      │           ├── ...
      ├── departmentB/
      └── org_conventions.properties