openresty/lua-resty-redis

Name

lua-resty-redis - Lua redis client driver for the ngx_lua based on the cosocket API

Table of Contents

• Name
• Status
• Description
• Synopsis
• Methods
  • new
  • connect
  • set_timeout
  • set_timeouts
  • set_keepalive
  • get_reused_times
  • close
  • init_pipeline
  • commit_pipeline
  • cancel_pipeline
  • hmset
  • hmget
  • array_to_hash
  • read_reply
  • add_commands
• Redis Authentication
• Redis Transactions
• Load Balancing and Failover
• Debugging
• Automatic Error Logging
• Error Handling and Connection Lifecycle
• Check List for Issues
• Limitations
• Installation
• TODO
• Community
  • English Mailing List
  • Chinese Mailing List
• Bugs and Patches
• Author
• Copyright and License
• See Also

Status

This library is considered production ready.

Description

This Lua library is a Redis client driver for the ngx_lua nginx module:

https://github.com/openresty/lua-nginx-module/#readme

This Lua library takes advantage of ngx_lua's cosocket API, which ensures 100% nonblocking behavior.

Note that at least ngx_lua 0.5.14 or OpenResty 1.2.1.14 is required.

Synopsis

    # you do not need the following line if you are using
    # the OpenResty bundle:
    lua_package_path "/path/to/lua-resty-redis/lib/?.lua;;";

    server {
        location /test {
            # need to specify the resolver to resolve the hostname
            resolver 8.8.8.8;

            content_by_lua_block {
                local redis = require "resty.redis"
                local red = redis:new()

                red:set_timeouts(1000, 1000, 1000) -- 1 sec

                -- or connect to a unix domain socket file listened
                -- by a redis server:
                --     local ok, err = red:connect("unix:/path/to/redis.sock")

                -- connect via ip address directly
                local ok, err = red:connect("127.0.0.1", 6379)

                -- or connect via hostname, need to specify resolver just like above
                local ok, err = red:connect("redis.openresty.com", 6379)

                if not ok then
                    ngx.say("failed to connect: ", err)
                    return
                end

                ok, err = red:set("dog", "an animal")
                if not ok then
                    ngx.say("failed to set dog: ", err)
                    -- the connection is closed automatically when the
                    -- request ends, see "Error Handling and Connection
                    -- Lifecycle" below
                    return
                end

                ngx.say("set result: ", ok)

                local res, err = red:get("dog")
                if not res then
                    ngx.say("failed to get dog: ", err)
                    return
                end

                if res == ngx.null then
                    ngx.say("dog not found.")
                    return
                end

                ngx.say("dog: ", res)

                red:init_pipeline()
                red:set("cat", "Marry")
                red:set("horse", "Bob")
                red:get("cat")
                red:get("horse")
                local results, err = red:commit_pipeline()
                if not results then
                    ngx.say("failed to commit the pipelined requests: ", err)
                    return
                end

                for i, res in ipairs(results) do
                    if type(res) == "table" then
                        if res[1] == false then
                            ngx.say("failed to run command ", i, ": ", res[2])
                        else
                            -- process the table value
                        end
                    else
                        -- process the scalar value
                    end
                end

                -- put it into the connection pool of size 100,
                -- with 10 seconds max idle time
                local ok, err = red:set_keepalive(10000, 100)
                if not ok then
                    ngx.say("failed to set keepalive: ", err)
                    return
                end

                -- or just close the connection right away:
                -- local ok, err = red:close()
                -- if not ok then
                --     ngx.say("failed to close: ", err)
                --     return
                -- end
            }
        }
    }

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Methods

All of the Redis commands have their own methods with the same name except all in lower case.

You can find the complete list of Redis commands here:

http://redis.io/commands

You need to check out this Redis command reference to see what Redis command accepts what arguments.

The Redis command arguments can be directly fed into the corresponding method call. For example, the "GET" redis command accepts a single key argument, then you can just call the "get" method like this:

    local res, err = red:get("key")

Similarly, the "LRANGE" redis command accepts three arguments, then you should call the "lrange" method like this:

    local res, err = red:lrange("nokey", 0, 1)

For example, "SET", "GET", "LRANGE", and "BLPOP" commands correspond to the methods "set", "get", "lrange", and "blpop".

The methods are generated on demand, so every Redis command works this way, including commands newer than this library and multi-word commands (the sub-command is just the first argument):

    -- CLIENT SETNAME myapp
    local res, err = red:client("setname", "myapp")

    -- BITFIELD mykey GET u8 0
    local res, err = red:bitfield("mykey", "get", "u8", 0)

Here are some more examples:

    -- HMGET myhash field1 field2 nofield
    local res, err = red:hmget("myhash", "field1", "field2", "nofield")

    -- HMSET myhash field1 "Hello" field2 "World"
    local res, err = red:hmset("myhash", "field1", "Hello", "field2", "World")

All these command methods returns a single result in success and nil otherwise. In case of errors or failures, it will also return a second value which is a string describing the error.

A Redis "status reply" results in a string typed return value with the "+" prefix stripped.

A Redis "integer reply" results in a Lua number typed return value.

A Redis "error reply" results in a false value and a string describing the error.

A non-nil Redis "bulk reply" results in a Lua string as the return value. A nil bulk reply results in a ngx.null return value.

A non-nil Redis "multi-bulk reply" results in a Lua table holding all the composing values (if any). If any of the composing value is a valid redis error value, then it will be a two element table {false, err}.

A nil multi-bulk reply returns in a ngx.null value.

See http://redis.io/topics/protocol for details regarding various Redis reply types.

In addition to all those redis command methods, the following methods are also provided:

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new

syntax: red, err = redis:new()

Creates a redis object. In case of failures, returns nil and a string describing the error.

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connect

syntax: ok, err = red:connect(host, port, options_table?)

syntax: ok, err = red:connect("unix:/path/to/unix.sock", options_table?)

Attempts to connect to the remote host and port that the redis server is listening to or a local unix domain socket file listened by the redis server.

Before actually resolving the host name and connecting to the remote backend, this method will always look up the connection pool for matched idle connections created by previous calls of this method.

The optional options_table argument is a Lua table holding the following keys:

• ssl

  If set to true, then uses SSL to connect to redis (defaults to false).

• ssl_verify

  If set to true, then verifies the validity of the server SSL certificate (defaults to false). Note that you need to configure the lua_ssl_trusted_certificate to specify the CA (or server) certificate used by your redis server. You may also need to configure lua_ssl_verify_depth accordingly.

• server_name

  Specifies the server name for the new TLS extension Server Name Indication (SNI) when connecting over SSL.

• pool

  Specifies a custom name for the connection pool being used. If omitted, then the connection pool name will be generated from the string template <host>:<port> or <unix-socket-path>, followed by /db=<db> when the db option is given and /user=<username> when the username option is in effect (for example 127.0.0.1:6379/db=1 or 127.0.0.1:6379/db=2/user=alice), so that connections to different databases or ACL users never share a pool. The password is never part of the pool name: every caller sharing a pool must authenticate the same way, or specify its own pool.

• db

  Selects the given Redis database with the SELECT command right after a new connection is established. The value must be a number (or a numeric string); anything else raises a Lua error. Connections reused from the connection pool are left untouched, which is why such connections get their own pool (see pool above). Omit this option for the default database 0. If SELECT fails, connect closes the connection and returns nil plus the error string "failed to select database <db>: <err>".

• password

  Authenticates a new connection with the AUTH command before SELECT (if any). Connections reused from the connection pool are left untouched. An empty string means no authentication. If AUTH fails, connect closes the connection and returns nil plus the error string "failed to authenticate: <err>". See also Redis Authentication.

• username

  The Redis ACL user name to authenticate as (AUTH <username> <password>, Redis 6.0+). Only used together with password; an empty string means the default user.

• tcp_keepalive

  If set to true, enables TCP keepalive (SO_KEEPALIVE) on the connection, whether newly established or reused from the pool. This lets an idle connection, typically one blocked in read_reply for Pub/Sub messages, notice a silently dropped peer. Only SO_KEEPALIVE is set: the probe timing comes from the operating system (on Linux net.ipv4.tcp_keepalive_time, 7200 seconds by default), so tune those kernel parameters or send a periodic PING if you need faster detection. Requires the setoption cosocket method (ngx_lua 0.10.18 with lua-resty-core, the default since OpenResty 1.15.8.1). If it cannot be enabled, connect closes the connection and returns nil plus the error string "failed to enable tcp keepalive: <err>".

Note that these keys are read from the whole options_table: a table that already carries a db, password, username or tcp_keepalive key for other purposes now has that meaning here.

• pool_size

  Specifies the size of the connection pool. If omitted and no backlog option was provided, no pool will be created. If omitted but backlog was provided, the pool will be created with a default size equal to the value of the lua_socket_pool_size directive. The connection pool holds up to pool_size alive connections ready to be reused by subsequent calls to connect, but note that there is no upper limit to the total number of opened connections outside of the pool. If you need to restrict the total number of opened connections, specify the backlog option. When the connection pool would exceed its size limit, the least recently used (kept-alive) connection already in the pool will be closed to make room for the current connection. Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so the size limit specified here also applies to every single Nginx worker process. Also note that the size of the connection pool cannot be changed once it has been created. Note that at least ngx_lua 0.10.14 is required to use this options.

• backlog

  If specified, this module will limit the total number of opened connections for this pool. No more connections than pool_size can be opened for this pool at any time. If the connection pool is full, subsequent connect operations will be queued into a queue equal to this option's value (the "backlog" queue). If the number of queued connect operations is equal to backlog, subsequent connect operations will fail and return nil plus the error string "too many waiting connect operations". The queued connect operations will be resumed once the number of connections in the pool is less than pool_size. The queued connect operation will abort once they have been queued for more than connect_timeout, controlled by set_timeout, and will return nil plus the error string "timeout". Note that at least ngx_lua 0.10.14 is required to use this options.

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set_timeout

syntax: red:set_timeout(time)

Sets the timeout (in ms) protection for subsequent operations, including the connect method.

Since version v0.28 of this module, it is advised that set_timeouts be used in favor of this method.

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set_timeouts

syntax: red:set_timeouts(connect_timeout, send_timeout, read_timeout)

Respectively sets the connect, send, and read timeout thresholds (in ms), for subsequent socket operations. Setting timeout thresholds with this method offers more granularity than set_timeout. As such, it is preferred to use set_timeouts over set_timeout.

This method was added in the v0.28 release.

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set_keepalive

syntax: ok, err = red:set_keepalive(max_idle_timeout, pool_size)

Puts the current Redis connection immediately into the ngx_lua cosocket connection pool.

You can specify the max idle timeout (in ms) when the connection is in the pool and the maximal size of the pool every nginx worker process.

In case of success, returns 1. In case of errors, returns nil with a string describing the error.

Only call this method in the place you would have called the close method instead. Calling this method will immediately turn the current redis object into the closed state. Any subsequent operations other than connect() on the current object will return the closed error.

A connection with an open transaction cannot be put into the pool: from the multi call until Redis has acknowledged an exec or discard, this method returns nil and the error string "in transaction" and the connection stays open. If exec or discard fails with a Redis error reply (for example EXECABORT or NOPERM), the connection is still considered to be in a transaction; close it. Pipelined multi, exec and discard take effect when their replies are read by commit_pipeline. Note that WATCH is not tracked: unwatch (or close) before keeping such a connection alive.

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get_reused_times

syntax: times, err = red:get_reused_times()

This method returns the (successfully) reused times for the current connection. In case of error, it returns nil and a string describing the error.

If the current connection does not come from the built-in connection pool, then this method always returns 0, that is, the connection has never been reused (yet). If the connection comes from the connection pool, then the return value is always non-zero. So this method can also be used to determine if the current connection comes from the pool.

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close

syntax: ok, err = red:close()

Closes the current redis connection and returns the status.

In case of success, returns 1. In case of errors, returns nil with a string describing the error.

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init_pipeline

syntax: red:init_pipeline()

syntax: red:init_pipeline(n)

Enable the redis pipelining mode. All subsequent calls to Redis command methods will automatically get cached and will send to the server in one run when the commit_pipeline method is called or get cancelled by calling the cancel_pipeline method.

This method always succeeds.

If the redis object is already in the Redis pipelining mode, then calling this method will discard existing cached Redis queries.

The optional n argument specifies the (approximate) number of commands that are going to add to this pipeline, which can make things a little faster.

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commit_pipeline

syntax: results, err = red:commit_pipeline()

Quits the pipelining mode by committing all the cached Redis queries to the remote server in a single run. All the replies for these queries will be collected automatically and are returned as if a big multi-bulk reply at the highest level.

This method returns nil and a Lua string describing the error upon failures.

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cancel_pipeline

syntax: red:cancel_pipeline()

Quits the pipelining mode by discarding all existing cached Redis commands since the last call to the init_pipeline method.

This method always succeeds.

If the redis object is not in the Redis pipelining mode, then this method is a no-op.

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hmset

syntax: res, err = red:hmset(myhash, field1, value1, field2, value2, ...)

syntax: res, err = red:hmset(myhash, { field1 = value1, field2 = value2, ... })

Special wrapper for the Redis "hmset" command.

When there are only three arguments (including the "red" object itself), then the last argument must be a Lua table holding all the field/value pairs.

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hmget

syntax: res, err = red:hmget(myhash, field1, field2, ...)

syntax: res, err = red:hmget(myhash, { field1, field2, ... })

Special wrapper for the Redis "hmget" command.

When there are only three arguments (including the "red" object itself) and the last one is a Lua table, the table is taken as the list of fields. The values are returned as a Lua table in the same order as the fields, exactly as for the plain form.

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array_to_hash

syntax: hash = red:array_to_hash(array)

Auxiliary function that converts an array-like Lua table into a hash-like table.

This method was first introduced in the v0.11 release.

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read_reply

syntax: res, err = red:read_reply()

Reading a reply from the redis server. This method is mostly useful for the Redis Pub/Sub API, for example,

    local cjson = require "cjson"
    local redis = require "resty.redis"

    local red = redis:new()
    local red2 = redis:new()

    red:set_timeouts(1000, 1000, 1000) -- 1 sec
    red2:set_timeouts(1000, 1000, 1000) -- 1 sec

    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("1: failed to connect: ", err)
        return
    end

    ok, err = red2:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("2: failed to connect: ", err)
        return
    end

    local res, err = red:subscribe("dog")
    if not res then
        ngx.say("1: failed to subscribe: ", err)
        return
    end

    ngx.say("1: subscribe: ", cjson.encode(res))

    res, err = red2:publish("dog", "Hello")
    if not res then
        ngx.say("2: failed to publish: ", err)
        return
    end

    ngx.say("2: publish: ", cjson.encode(res))

    res, err = red:read_reply()
    if not res then
        ngx.say("1: failed to read reply: ", err)
        return
    end

    ngx.say("1: receive: ", cjson.encode(res))

    red:close()
    red2:close()

Running this example gives the output like this:

1: subscribe: ["subscribe","dog",1]
2: publish: 1
1: receive: ["message","dog","Hello"]

The following class methods are provided:

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add_commands

syntax: hash = redis.add_commands(cmd_name1, cmd_name2, ...)

WARNING this method is now deprecated since we already do automatic Lua method generation for any redis commands the user attempts to use and thus we no longer need this.

Adds new redis commands to the resty.redis class. Here is an example:

    local redis = require "resty.redis"

    redis.add_commands("foo", "bar")

    local red = redis:new()

    red:set_timeouts(1000, 1000, 1000) -- 1 sec

    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("failed to connect: ", err)
        return
    end

    local res, err = red:foo("a")
    if not res then
        ngx.say("failed to foo: ", err)
    end

    res, err = red:bar()
    if not res then
        ngx.say("failed to bar: ", err)
    end

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Redis Authentication

Redis uses the AUTH command to do authentication: http://redis.io/commands/auth

There is nothing special for this command as compared to other Redis commands like GET and SET. So one can just invoke the auth method on your resty.redis instance. Here is an example:

    local redis = require "resty.redis"
    local red = redis:new()

    red:set_timeouts(1000, 1000, 1000) -- 1 sec

    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("failed to connect: ", err)
        return
    end

    local res, err = red:auth("foobared")
    if not res then
        ngx.say("failed to authenticate: ", err)
        return
    end

where we assume that the Redis server is configured with the password foobared in the redis.conf file:

requirepass foobared

If the password specified is wrong, then the sample above will output the following to the HTTP client:

failed to authenticate: WRONGPASS invalid username-password pair or user is disabled.

(ERR invalid password on Redis servers older than 6.0.)

To authenticate as a Redis ACL user (Redis 6.0+), pass the user name first:

    local res, err = red:auth("alice", "foobared")

Instead of calling auth yourself on every new connection, you can also pass the password (and username) options to connect, which runs AUTH only for connections that do not come from the connection pool.

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Redis Transactions

This library supports the Redis transactions. Here is an example:

    local cjson = require "cjson"
    local redis = require "resty.redis"
    local red = redis:new()

    red:set_timeouts(1000, 1000, 1000) -- 1 sec

    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("failed to connect: ", err)
        return
    end

    local ok, err = red:multi()
    if not ok then
        ngx.say("failed to run multi: ", err)
        return
    end
    ngx.say("multi ans: ", cjson.encode(ok))

    local ans, err = red:set("a", "abc")
    if not ans then
        ngx.say("failed to run sort: ", err)
        return
    end
    ngx.say("set ans: ", cjson.encode(ans))

    local ans, err = red:lpop("a")
    if not ans then
        ngx.say("failed to run sort: ", err)
        return
    end
    ngx.say("set ans: ", cjson.encode(ans))

    ans, err = red:exec()
    ngx.say("exec ans: ", cjson.encode(ans))

    red:close()

Then the output will be

multi ans: "OK"
set ans: "QUEUED"
set ans: "QUEUED"
exec ans: ["OK",[false,"ERR Operation against a key holding the wrong kind of value"]]

A connection cannot be put back into the connection pool while a transaction is open, see set_keepalive.

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Redis Module

This library supports the Redis module. Here is an example with RedisBloom module:

    local cjson = require "cjson"
    local redis = require "resty.redis"
    -- register the module prefix "bf" for RedisBloom
    redis.register_module_prefix("bf")

    local red = redis:new()

    local ok, err = red:connect("127.0.0.1", 6379)
    if not ok then
        ngx.say("failed to connect: ", err)
        return
    end

    -- call BF.ADD command with the prefix 'bf'
    res, err = red:bf():add("dog", 1)
    if not res then
        ngx.say(err)
        return
    end
    ngx.say("receive: ", cjson.encode(res))

    -- call BF.EXISTS command
    res, err = red:bf():exists("dog")
    if not res then
        ngx.say(err)
        return
    end
    ngx.say("receive: ", cjson.encode(res))

Load Balancing and Failover

You can trivially implement your own Redis load balancing logic yourself in Lua. Just keep a Lua table of all available Redis backend information (like host name and port numbers) and pick one server according to some rule (like round-robin or key-based hashing) from the Lua table at every request. You can keep track of the current rule state in your own Lua module's data, see https://github.com/openresty/lua-nginx-module/#data-sharing-within-an-nginx-worker

Similarly, you can implement automatic failover logic in Lua at great flexibility.

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Debugging

It is usually convenient to use the lua-cjson library to encode the return values of the redis command methods to JSON. For example,

    local cjson = require "cjson"
    ...
    local res, err = red:mget("h1234", "h5678")
    if res then
        print("res: ", cjson.encode(res))
    end

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Automatic Error Logging

By default the underlying ngx_lua module does error logging when socket errors happen. If you are already doing proper error handling in your own Lua code, then you are recommended to disable this automatic error logging by turning off ngx_lua's lua_socket_log_errors directive, that is,

    lua_socket_log_errors off;

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Error Handling and Connection Lifecycle

The two error shapes returned by the command methods mean different things:

• false, err is a Redis error reply (for example ERR wrong number of arguments). The connection is fine and can still be used or put into the pool with set_keepalive, unless Redis itself closed it, as it does after protocol errors or when maxclients is exceeded.
• nil, err from a command method is a connection failure (closed, timeout, connection reset by peer, ...). Do not reuse the connection: call close and connect again. After a read timeout this library has already closed the socket for you, so a subsequent set_keepalive returns closed; that is expected.

Two exceptions to the second rule: a timeout from read_reply in subscribe mode is a normal polling result and the connection stays usable; after a timed-out blpop/brpop the connection must be closed and never kept alive, because the late reply would be read by the next user. Errors describing this library's own state (in transaction, subscribed state, not subscribed, no pipeline, not initialized) are not connection failures.

A connection that is neither closed nor kept alive is closed automatically when the current request (or timer) finishes. This is not a leak, but the connection is not reused either; return early from error paths as in the Synopsis if that is acceptable to you.

When setting the max_idle_timeout of set_keepalive, keep it below the idle timeout of anything between NGINX and Redis (load balancers, NAT, firewalls) and below Redis' own timeout setting, otherwise pooled connections come back dead and the next command fails with closed, connection reset by peer or timeout. A max_idle_timeout of 0 means unlimited.

The pool_size of set_keepalive (or of connect) bounds the number of idle connections kept in the pool, not the number of concurrent connections; use the backlog option of connect to limit the latter.

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Check List for Issues

1. Ensure you configure the connection pool size properly in the set_keepalive. Basically if your Redis can handle n concurrent connections and your NGINX has m workers, then the connection pool size should be configured as n/m. For example, if your Redis usually handles 1000 concurrent requests and you have 10 NGINX workers, then the connection pool size should be 100. Similarly if you have p different NGINX instances, then connection pool size should be n/m/p.
2. Ensure the backlog setting on the Redis side is large enough. For Redis 2.8+, you can directly tune the tcp-backlog parameter in the redis.conf file (and also tune the kernel parameter SOMAXCONN accordingly at least on Linux). You may also want to tune the maxclients parameter in redis.conf.
3. Ensure you are not using too short timeout setting in the set_timeout or set_timeouts methods. If you have to, try redoing the operation upon timeout and turning off automatic error logging (because you are already doing proper error handling in your own Lua code).
4. If your NGINX worker processes' CPU usage is very high under load, then the NGINX event loop might be blocked by the CPU computation too much. Try sampling a C-land on-CPU Flame Graph and Lua-land on-CPU Flame Graph for a typical NGINX worker process. You can optimize the CPU-bound things according to these Flame Graphs.
5. If your NGINX worker processes' CPU usage is very low under load, then the NGINX event loop might be blocked by some blocking system calls (like file IO system calls). You can confirm the issue by running the epoll-loop-blocking-distr tool against a typical NGINX worker process. If it is indeed the case, then you can further sample a C-land off-CPU Flame Graph for a NGINX worker process to analyze the actual blockers.
6. If your redis-server process is running near 100% CPU usage, then you should consider scale your Redis backend by multiple nodes or use the C-land on-CPU Flame Graph tool to analyze the internal bottlenecks within the Redis server process.

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Limitations

• This library cannot be used in code contexts like init_by_lua*, set_by_lua*, log_by_lua*, and header_filter_by_lua* where the ngx_lua cosocket API is not available.
• The resty.redis object instance cannot be stored in a Lua variable at the Lua module level, because it will then be shared by all the concurrent requests handled by the same nginx worker process (see https://github.com/openresty/lua-nginx-module/#data-sharing-within-an-nginx-worker ) and result in bad race conditions when concurrent requests are trying to use the same resty.redis instance (you would see the "bad request" or "socket busy" error to be returned from the method calls). You should always initiate resty.redis objects in function local variables or in the ngx.ctx table. These places all have their own data copies for each request.

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Installation - Build from source

# Clone latest release , assuming v0.29
wget https://github.com/openresty/lua-resty-redis/archive/refs/tags/v0.29.tar.gz

# Extract
tar -xvzf v0.29.tar.gz

# go into directory
cd lua-resty-redis-0.29

export LUA_LIB_DIR=/usr/local/openresty/site/lualib

# Compile and Install
make install

# Now compiled path will be outputted
# /usr/local/lib/lua/resty = lua_package_path in nginx conf

Installation Notes

If you are using the OpenResty bundle (http://openresty.org ), then you do not need to do anything because it already includes and enables lua-resty-redis by default. And you can just use it in your Lua code, as in

    local redis = require "resty.redis"
    ...

If you are using your own nginx + ngx_lua build, then you need to configure the lua_package_path directive to add the path of your lua-resty-redis source tree to ngx_lua's LUA_PATH search path, as in

    # nginx.conf
    http {
        lua_package_path "/path/to/lua-resty-redis/lib/?.lua;;";
        ...
    }

Ensure that the system account running your Nginx ''worker'' proceses have enough permission to read the .lua file.

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TODO

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Community

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English Mailing List

The openresty-en mailing list is for English speakers.

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Chinese Mailing List

The openresty mailing list is for Chinese speakers.

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Bugs and Patches

Please report bugs or submit patches by

1. creating a ticket on the GitHub Issue Tracker,
2. or posting to the OpenResty community.

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Author

Yichun "agentzh" Zhang (章亦春) [email protected], OpenResty Inc.

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Copyright and License

This module is licensed under the BSD license.

Copyright (C) 2012-2017, by Yichun Zhang (agentzh) [email protected], OpenResty Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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See Also

• the ngx_lua module: https://github.com/openresty/lua-nginx-module/#readme
• the redis wired protocol specification: http://redis.io/topics/protocol
• the lua-resty-memcached library
• the lua-resty-mysql library

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