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Module Plasma_client_config

module Plasma_client_config: sig .. end
Configuration of clients

class type client_config = object .. end
val parse_config_file : string -> client_config list
Parses the config file and returns all included configs

The config file should look like:

      plasmafs {
        cluster {
          clustername = "cluster1";
          node { addr = "hostname:port" };
          node { addr = "hostname:port" };
        ... (* more [cluster] sections possible *)

As usual, one can also have

       node_list = "filename";
       port = <default_port>;

instead of several node/addr sections. node_list points then to another file enumerating the hostnames (and optionally ports).

val get_config : ?clustername:string ->
?nn_nodes:string list -> unit -> client_config
get_config (): This is the standard way for clients to obtain a config object. Generally, the settings can be passed directly to get_config, by environment variables, and by the config file ~/.plasmafs.

  • If both clustername and nn_nodes are passed, this configuration is taken
  • The file ~/.plasmafs is parsed and all configurations are extracted.
  • If a clustername is passed, this configuration is selected (it is an error if this does not exist). Environment variables are ignored.
  • If no clustername is passed, and the environment variable PLASMAFS_CLUSTER is set, this variable selects the cluster. If also PLASMAFS_NAMENODES is set, the namenodes are configured from there. Otherwise the PLASMAFS_CLUSTER must be described in the configuration file.
  • Otherwise, the first configuration from ~/.plasmafs is selected.
  • Otherwise the algorithm fails.
The precedence in short: function arguments, then environment variable, then first entry from config file. Only if the cluster name is taken on a certain precdence level, the host/port list on this level is meaningful.

PLASMAFS_NAMENODES enumerates the namenodes in host:port syntax, separated by commas.

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