ConfigServer

Concept

Many applications need configuration that might change at runtime. ConfigServer can deliver configuration which is stored in a git repository.

The repository is cloned into the local file system and pulled from the origin at regular intervals.

Installation

The package can be installed by adding config_server to your list of dependencies in mix.exs:

def deps do
  [
    {:config_server, "~> 0.4.0"}
  ]
end

Configuration

If you are using http:

config :config_server,
  repo_url: "https://ghp_XXX@github.com/odo/config_server",
  repo_path: "/tmp/config_server_checkout",
  pull_interval_ms: 1000,
  state_change_fun: fn(old_config, new_config) -> IO.inspect({old_config, new_config}) end

If you are using ssh and want a specific branch to be used plus a custom parser:

config :config_server,
  repo_url: "git@github.com:odo/config_server",
  git_ssh_command: "ssh -i ~/.ssh/my_private_key", 
  repo_path: "/tmp/config_server_checkout",
  branch: "staging",
  pull_interval_ms: 1000,
  state_change_fun: fn(old_config, new_config) -> IO.inspect({old_config, new_config}) end,
  parsing_fun: {MyParser, :parse}

repo_url

This can be

• A directory file:///path/to/repo/directory
• A HTTP URL like https://token@github.com/foo/bar
• SSH path like git@github.com:odo/config_server together with git_ssh_command (see above)

repo_path

A path where the checkout of your configuration repository lives.

state_change_fun as ((any(), any()) -> :ok | :error | {:error, any()}) | {atom(), atom()}

This can be skipped or can be defined as {module, function}. ConfigServer will pass in the old and new configuration as arguments. Initially, the old configuration will be nil. If state_change_fun returns :error or {:error, something} then that means that the configuration is faulty and ConfigServer rolls back to the previous configuration.

parsing_fun ((String.t()) -> {:ok, any()} | {:error, any()}) | {atom(), atom()}

The default parser looks for Json files, parses them and puts them into one big map. If you like to do something else you can pass the :parsing_fun option to turn the checkout path of the repo into the configuration you need.

Usage

To retrieve the current configuration, call ConfigServer.config().

Format

The config repo is returned as a map with file names as keys and file content as values. Json files are parsed and the .json ending is filtered out. Files and directories starting with dots are ignored.