eredis_cluster is a wrapper for eredis to support cluster mode of Redis 3.0.0+
Improvements compared to adrienmo/eredis_cluster:
- Support of TLS introduced in Redis 6
- Uses Nordix/eredis
- Many Dialyzer corrections
- Elvis code formatting
- Containerized testing
- Added APIs:
connect/2- Connect to init nodes, with optionsqa2/1- query all nodes with re-attempts, returns [{Node, Result},..]q_noreply/1- query a single Redis instance but wont wait for its resultload_script/1- pre-load script to all Redis instancesscan/4- Perform a scan command on given Redis instancedisconnect/1- disconnect from given Redis instancesget_pool_by_command/1- get which Redis pool that handles a given commandget_pool_by_key/1- get which Redis pool that handles a given keyget_cluster_nodes/0- get cluster nodes information list (CLUSTER NODES)get_cluster_slots/0- get cluster slots information (CLUSTER SLOTS)
- Changed behaviour:
qa/1- query all nodes, now with re-attemptsget_cluster_slots/2- Gives descriptive errors when failing
- Correct last Dialyzer warnings
- Improve test coverage
get_cluster_slots/2, throw a reply?, improve tests- Improve test suite to demonstrate the case where Redis cluster is crashing, resharding, recovering...
The directory contains a Makefile that uses rebar3.
Setup a Redis cluster and start the tests using following commands:
make
make start # Start a local Redis cluster
make test # Run tests towards the cluster
make stop # Teardown the Redis clusterTo configure the Redis cluster, you can use an application variable (probably in your app.config):
{eredis_cluster,
[
{init_nodes,[
{"127.0.0.1", 30001},
{"127.0.0.1", 30002}
]},
{pool_size, 5},
{pool_max_overflow, 10},
{password, "redis_pw"},
{socket_options, [{send_timeout, 6000}, ...]},
{tls, [{cacertfile, "ca.crt"}, ...]}
]
}
You don't need to specify all nodes of your configuration as eredis_cluster will
retrieve them through the command CLUSTER SLOTS at runtime.
init_nodes: List of Redis instances to fetch cluster information from. Default:[]pool_size: Number of connected clients to each Redis instance. Default:10pool_max_overflow: Max number of extra clients that can be started when the pool is exhausted. Default:0password: Password to use for a Redis cluster configured withrequirepass. Default:""(i.e. AUTH not sent)socket_options: Extra socket options. Enables selecting host interface or perf. tuning. Default:[]tls: Enable TLS/SSL and use specified TLSOptions. Default: TLS not enabled.
An alternative is to set configurations programmatically via set_env() and eredis_cluster:connect/1.
application:set_env(eredis_cluster, pool_size, 5),
application:set_env(eredis_cluster, pool_max_overflow, 10),
application:set_env(eredis_cluster, password, "redis_pw"),
application:set_env(eredis_cluster, socket_options, [{send_timeout, 6000}]),
application:set_env(eredis_cluster, tls, [{cacertfile, "ca.crt"},
{certfile, "client.crt"},
{keyfile, "client.key"}]),
%% Set initial nodes and perform a controlled connect
eredis_cluster:connect([{"127.0.0.1", 30001},
{"127.0.0.1", 30002}]).It is also possible to give options while doing a connect using eredis_cluster:connect/2 instead.
The given options will precede options set via application configuration,
i.e will be prepended to the property list.
Options = [{tls, [{cacertfile, "ca.crt"},
{certfile, "client.crt"},
{keyfile, "client.key"}]}],
eredis_cluster:connect([{"127.0.0.1", 30001},
{"127.0.0.1", 30002}], Options).%% Start the application
eredis_cluster:start().
%% Simple command
eredis_cluster:q(["GET","abc"]).
%% Pipeline
eredis_cluster:qp([["LPUSH", "a", "a"], ["LPUSH", "a", "b"], ["LPUSH", "a", "c"]]).
%% Pipeline in multiple node (keys are sorted by node, a pipeline request is
%% made on each node, then the result is aggregated and returned. The response
%% keep the command order
eredis_cluster:qmn([["GET", "a"], ["GET", "b"], ["GET", "c"]]).
%% Transaction
eredis_cluster:transaction([["LPUSH", "a", "a"], ["LPUSH", "a", "b"], ["LPUSH", "a", "c"]]).
%% Transaction Function
Function = fun(Worker) ->
eredis_cluster:qw(Worker, ["WATCH", "abc"]),
{ok, Var} = eredis_cluster:qw(Worker, ["GET", "abc"]),
%% Do something with Var %%
Var2 = binary_to_integer(Var) + 1,
{ok, Result} = eredis_cluster:qw(Worker,[["MULTI"], ["SET", "abc", Var2], ["EXEC"]]),
lists:last(Result)
end,
eredis_cluster:transaction(Function, "abc").
%% Optimistic Locking Transaction
Function = fun(GetResult) ->
{ok, Var} = GetResult,
Var2 = binary_to_integer(Var) + 1,
{[["SET", Key, Var2]], Var2}
end,
Result = optimistic_locking_transaction(Key, ["GET", Key], Function),
{ok, {TransactionResult, CustomVar}} = Result
%% Atomic Key update
Fun = fun(Var) -> binary_to_integer(Var) + 1 end,
eredis_cluster:update_key("abc", Fun).
%% Atomic Field update
Fun = fun(Var) -> binary_to_integer(Var) + 1 end,
eredis_cluster:update_hash_field("abc", "efg", Fun).
%% Eval script, both script and hash are necessary to execute the command,
%% the script hash should be precomputed at compile time otherwise, it will
%% execute it at each request. Could be solved by using a macro though.
Script = "return redis.call('set', KEYS[1], ARGV[1]);",
ScriptHash = "4bf5e0d8612687699341ea7db19218e83f77b7cf",
eredis_cluster:eval(Script, ScriptHash, ["abc"], ["123"]).
%% Flush DB
eredis_cluster:flushdb().
%% Query on all cluster server
eredis_cluster:qa(["FLUSHDB"]).
%% Execute a query on the server containing the key "TEST"
eredis_cluster:qk(["FLUSHDB"], "TEST").Following Redis-log indicates that Redis accepts TLS, but the client is not configured for TLS.
# Error accepting a client connection: error:1408F10B:SSL routines:ssl3_get_record:wrong version number (conn: fd=12)
Debug logging for TLS connections can be enabled in eredis_cluster by the connect option: {log_level, debug}