The redgrid from alepharchives

redgrid's Introduction

About

Redgrid performs automatic Erlang node discovery through a shared Redis pub/sub channel.

Build

$ make

Run

Start Redgrid with no arguments

$ erl -pa ebin deps/*/ebin
1> redgrid:start_link().
{ok,<0.33.0>}
2> whereis(redgrid).
<0.33.0>

Start Redgrid with custom Redis url

$ erl -pa ebin deps/*/ebin
1> redgrid:start_link([{redis_url, "redis://localhost:6379/"}]).
{ok,<0.33.0>}

Start Redgrid as a non-registered (anonymous) process

$ erl -pa ebin deps/*/ebin
1> redgrid:start_link([anonymous]).
{ok,<0.33.0>}

Start with arbitrary meta data

$ erl -pa ebin deps/*/ebin
1> redgrid:start_link([{<<"foo">>, <<"bar">>}]).
{ok,<0.33.0>}

Example

TAB 1

Start foo node

$ erl -pa ebin deps/*/ebin -name foo@`hostname`
([email protected])1> redgrid:start_link().
{ok,<0.39.0>}

TAB 2

Start bar node

$ erl -pa ebin deps/*/ebin -name bar@`hostname`
([email protected])1> redgrid:start_link().
{ok,<0.39.0>}

View registered nodes

([email protected])2> redgrid:nodes().
[{'[email protected]',[<<"ip">>, <<"localhost">>]},
 {'[email protected]',[{<<"ip">>, <<"localhost">>}]}]
([email protected])3> [node()|nodes()].
['[email protected]', '[email protected]']

Update meta data for bar node

([email protected])4> redgrid:update_meta([{weight, 50}]).
ok

TAB 1

View registered nodes (including updated meta data for bar)

([email protected])2> redgrid:nodes().
[{'[email protected]',[<<"ip">>, <<"localhost">>]},
 {'[email protected]',[{<<"ip">>,<<"localhost">>},
                                            {<<"weight">>, <<"50">>}]}]

Diagram

This diagram demonstrates what's happening underneath the covers when the foo node joins a cluster comprised of a single node (bar).

ENV VARS

LOCAL_IP: The IP written to Redis to which other nodes will attempt to connect
DOMAIN: Used to build Redis key and channel names
VERSION: Used to build Redis key and channel names

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