A Postgres database connection pool
$ rebar3 compile
$ rebar3 edoc
Configuration can be passed through maps or proplists. App config files will be setting config for the ppool app. Configuration is in the following format:
-type(resolver(t) :: {env, string()} | % get system environment variable
{fn, atom(), atom()} | % Call a method with 0 arity. Return should be either no_value or {value, Value}
{chain, [resolver(t)]} | % Chain of resolvers to evaluate in order
{value, t()}, % Set to a specific value (useful if it could collide with resolver values)
t()). % A value to resolve to
% Note: resolver(t) can only get the following types from environment variables:
% integer(), string(), float(), atom(), binary(), boolean()
% Any other type must be provided as a term or through a function call
#{
sup_name => atom(), % Optional, changes registered names for pool supervisor
default_pool => atom(), % Optional, default pool to use with ppool_db calls
id_siffix => binary(), % Optional, binary to add to end of table name to get ID column
% Defaults to <<"_id">>
use_inflection => boolean(), % Optional, determines if table names should be turned to singular
% when determining column name (e.g. "users" => "user")
% Default is true
inflection_method => {atom(), atom()}, % {Module, Method} to use for inflection
% Defaults to {ppool_inflection, singular}
pools => [
#{
name => atom(), % Required, name to register pool as
% Used when specifying the pool to ppool_db calls
pool => #{
size => resolver(integer()), % Optional, maximum connection pool size. Default 10
max_overflow => resolver(integer()), % Optional, maximum number of connections created if pool is emtpy. Default 10
strategy => resolver(lifo | fifo) % Optional, determines how freed connections are put back in the. Default lifo queue
},
db => #{
hostname => resolver(string() | binary()), % Required, DB host name
database => resolver(string() | binary()), % Required, database to connect to
username => resolver(string() | binary()), % Required, username to login as
password => resolver(string() | binary()), % Required, password to login with
port => resolver(integer()), % Optional, port to connect to (default 5432)
ssl => resolver(boolean() | 'required'), % Optional, whether to use SSL
ssl_opts => resolver([ssl_option()]), % Optional, epgsql SSL params
tcp_opts => resolver([tcp_option()]), % Optional, epgsql TCP params
socket_active => resolver(boolean() | integer()), % Optional, epgsql socket active option
async => resolver(atom() | pid()), % Optional, process to receive LISTEN/NOTIFY messages
codecs => resolver([{epgsql_codec:codec_mod(), any()}]), % Optional, epgsql codec args
nulls => resolver([any()]), % Optional, epgsq NULL terms
replication => resolver(Replication :: string()) % Optional, replication string info
}
}
]
}