lua-kong-nginx-module - Nginx C module that exposes a Lua API to dynamically control Nginx
- Name
- Description
- Install
- Directives
- Variables
- Methods
- resty.kong.tls.disable_session_reuse
- resty.kong.tls.get_full_client_certificate_chain
- resty.kong.tls.set_upstream_cert_and_key
- resty.kong.tls.set_upstream_ssl_trusted_store
- resty.kong.tls.set_upstream_ssl_verify
- resty.kong.tls.set_upstream_ssl_verify_depth
- resty.kong.tls.get_ssl_pointer
- resty.kong.grpc.set_authority
- resty.kong.tls.disable_proxy_ssl
- resty.kong.var.patch_metatable
- resty.kong.tag.get
- resty.kong.log.set_log_level
- resty.kong.log.get_log_level
- resty.kong.peer_conn.get_last_peer_connection_cached
- License
Kong often needs to be able to change Nginx behavior at runtime. Traditionally this has been done using various core patches. This module attempts to unify those approaches and ensure the least amount of modifications made directly to Nginx to support future maintainability.
Patches from openresty-patches are required for this module to compile successfully. You may use the openresty-build-tools script to automatically build an OpenResty binary with required patches as well as this module included.
This module can be installed just like any ordinary Nginx C module, using the
--add-module configuration option:
./configure --prefix=/usr/local/kong-nginx \
--add-module=/path/to/lua-kong-nginx-module \
...
syntax: lua_kong_load_var_index $variable | default;
context: http
Ensure variable is indexed. Note that variables defined by set directive
are always indexed by default and does not need to be defined here again.
Common variables defined by other modules that are already indexed:
$proxy_host$proxy_internal_body_length$proxy_internal_chunked$remote_addr$remote_user$request$http_referer$http_user_agent$host
Specially, use lua_kong_load_var_index default to
index commonly used variables as follows:
$args$is_args$bytes_sent$content_type$http_authorization$http_connection$http_host$http_kong_debug$http_proxy$http_proxy_connection$http_te$http_upgrade$http_x_forwarded_for$http_x_forwarded_host$http_x_forwarded_path$http_x_forwarded_port$http_x_forwarded_prefix$http_x_forwarded_proto$http_x_kong_request_debug$http_x_kong_request_debug_token$http_x_kong_request_debug_log$https$http2$realip_remote_addr$realip_remote_port$remote_port$request_length$request_method$request_time$request_uri$scheme$server_addr$server_port$ssl_cipher$ssl_client_raw_cert$ssl_client_verify$ssl_protocol$ssl_server_name$upstream_http_connection$upstream_http_trailer$upstream_http_upgrade$upstream_status
See resty.kong.var.patch_metatable on how to enable indexed variable access.
syntax: lua_kong_set_static_tag value;
context: location(http subsystem) server(stream subsystem)
Add a static tag string for Nginx's location(http subsystem) or server(stream subsystem) block,
which can be accessed in Lua land by resty.kong.tag.get.
Notice: the value of tag is bound with the location(http subsystem) or server(stream subsystem) block
where it is defined.
So if you defined multi tags in different location(http subsystem) or server(stream subsystem) block,
you will always get the value where your Lua code runs in but not others.
syntax: lua_kong_error_log_request_id $variable;
context: http server location
Append a Request ID to the standard error log format, load the ID value from $variable. $variable must be previously defined.
For example, with this configuration:
lua_kong_error_log_request_id $request_id;
An error log line may look similar to the following:
2023/09/06 11:33:36 [error] 94085#0: *6 [lua] content_by_lua(nginx.conf:27):7: hello world, client: 127.0.0.1, server: , request: "GET /foo HTTP/1.1", host: "localhost:8080", request_id: "cd7706e903db672ac5fac333bc8db5ed"
Unique request identifier generated from 16 pseudo-random bytes, in hexadecimal. This variable is indexed.
syntax: succ, err = resty.kong.tls.disable_session_reuse()
context: ssl_certificate_by_lua*
subsystems: http stream
Prevents the TLS session for the current connection from being reused by disabling session ticket and session ID for the current TLS connection.
This function returns true when the call is successful. Otherwise it returns
nil and a string describing the error.
syntax: pem_chain, err = resty.kong.tls.get_full_client_certificate_chain()
context: rewrite_by_lua*, access_by_lua*, content_by_lua*, log_by_lua*, preread_by_lua*
subsystems: http stream
Returns the PEM encoded downstream client certificate chain with the client certificate at the top and intermediate certificates (if any) at the bottom.
If client did not present any certificate or if session was reused, then this
function will return nil.
This is functionally similar to $ssl_client_raw_cert provided by ngx_http_ssl_module, with the notable exception that this function also returns any certificate chain client sent during handshake.
If the TLS session was reused, (signaled by $ssl_session_reused returns "r"), then no client certificate information will be available as a full handshake never occurred. In this case caller should use $ssl_session_id to associate this session with one of the previous handshakes to identify the connecting client.
syntax: ok, err = resty.kong.tls.set_upstream_cert_and_key(chain, key)
context: rewrite_by_lua*, access_by_lua*, balancer_by_lua*, preread_by_lua*
subsystems: http stream
Overrides and enables sending client certificate while connecting to the upstream in the current request.
chain is the client certificate and intermediate chain (if any) returned by
functions such as ngx.ssl.parse_pem_cert.
key is the private key corresponding to the client certificate returned by
functions such as ngx.ssl.parse_pem_priv_key.
On success, this function returns true and future handshakes with upstream servers
will always use the provided client certificate. Otherwise nil and a string describing the error
will be returned.
This function can be called multiple times in the same request. Later calls override previous ones.
syntax: ok, err = resty.kong.tls.set_upstream_ssl_trusted_store(store)
context: rewrite_by_lua*, access_by_lua*, balancer_by_lua*, preread_by_lua*
subsystems: http stream
Set upstream ssl verification trusted store of current request. Global setting set by
proxy_ssl_trusted_certificate will be overwritten for the current request.
store is a table object that can be created by
resty.openssl.x509.store.new.
On success, this function returns true and future handshakes with upstream servers
will be verified with given store. Otherwise nil and a string describing the
error will be returned.
This function can be called multiple times in the same request. Later calls override previous ones.
Example:
local x509 = require("resty.openssl.x509")
local crt, err = x509.new([[-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----]])
if err then
ngx.log(ngx.ERR, "failed to parse cert: ", err)
ngx.exit(500)
end
local store = require("resty.openssl.x509.store")
local st, err = store.new()
if err then
ngx.log(ngx.ERR, "failed to create store: ", err)
ngx.exit(500)
end
local ok, err = st:add(crt)
if err then
ngx.log(ngx.ERR, "failed to add cert to store: ", err)
ngx.exit(500)
end
-- st:add can be called multiple times, also accept a crl
-- st:add(another_crt)
-- st:add(crl)
-- OR
-- st:use_default() to load default CA bundle
local tls = require("resty.kong.tls")
local ok, err = tls.set_upstream_ssl_trusted_store(st.ctx)
if err then
ngx.log(ngx.ERR, "failed to set upstream trusted store: ", err)
ngx.exit(500)
end
local ok, err = tls.set_upstream_ssl_verify(true)
if err then
ngx.log(ngx.ERR, "failed to set upstream ssl verify: ", err)
ngx.exit(500)
endsyntax: ok, err = resty.kong.tls.set_upstream_ssl_verify(verify)
context: rewrite_by_lua*, access_by_lua*, balancer_by_lua*, preread_by_lua*
subsystems: http stream
Set upstream ssl verification enablement of current request to the given boolean
argument verify. Global setting set by proxy_ssl_verify will be overwritten.
On success, this function returns true. Otherwise nil and a string
describing the error will be returned.
This function can be called multiple times in the same request. Later calls override previous ones.
syntax: ok, err = resty.kong.tls.set_upstream_ssl_verify_depth(depth)
context: rewrite_by_lua*, access_by_lua*, balancer_by_lua*, preread_by_lua*
subsystems: http stream
Set upstream ssl verification depth of current request to the given non-negative integer
argument depth. Global setting set by proxy_ssl_verify_depth will be overwritten.
On success, this function returns true. Otherwise nil and a string
describing the error will be returned.
This function can be called multiple times in the same request. Later calls override previous ones.
syntax: ssl_ptr, err = resty.kong.tls.get_ssl_pointer(sock)
context: rewrite_by_lua*, access_by_lua*, content_by_lua*, log_by_lua*, preread_by_lua*
subsystems: http stream
Retrieves the OpenSSL SSL* object for the current tcpsock sock.
On success, this function returns the pointer of type SSL. Otherwise nil and a string
describing the error will be returned.
syntax: ok, err = resty.kong.grpc.set_authority(new_authority)
context: rewrite_by_lua*, access_by_lua*, balancer_by_lua*
subsystems: http
Overrides the :authority pseudo header sent to gRPC upstream by
ngx_http_grpc_module.
This function is a capability not possible in Nginx through means of config
directive alone. Reason being Nginx auto-generates the :authority pseudo header
without giving us a way to override it at config time. Closest being
grpc_set_header Host "foo.example.com", but this will cause the gRPC
module to use the Host header and not generate the :authority pseudo header,
causing problems for certain gRPC server.
When called, this function accepts a new value to override the :authority
pseudo header that will be generated by the ngx_http_grpc_module for the
current request.
The new_authority parameter can not be an empty string.
On success, this function returns true. Otherwise nil and a string
describing the error will be returned.
This function can be called multiple times in the same request. Later calls override previous ones.
If called in the balancer_by_lua context, the request needs to be recreated
(see balancer.recreate.
syntax: ok, err = resty.kong.tls.disable_proxy_ssl()
context: preread_by_lua*, balancer_by_lua*
subsystems: stream
Disables the TLS handshake to upstream for ngx_stream_proxy_module.
Effectively this overrides proxy_ssl directive to off setting
for the current stream session.
This function has no side effects if the proxy_ssl off; setting has already
been specified inside nginx.conf or if this function has been previously
called from the current session.
syntax: resty.kong.var.patch_metatable()
context: init_by_lua
subsystems: http
Indexed variable access is a faster way of accessing Nginx variables for OpenResty.
This method patches the metatable of ngx.var to enable index access to variables
that supports it. It should be called once in the init phase which will be effective for
all subsequent ngx.var uses.
For variables that does not have indexed access, the slower hash based lookup will be used instead (this is the OpenResty default behavior).
To ensure a variable can be accessed using index, you can use the lua_kong_load_var_index directive.
syntax: resty.kong.tag.get()
context: rewrite_by_lua*, access_by_lua*, content_by_lua*, log_by_lua*, header_filter_by_lua*, body_filter_by_lua*
subsystems: http stream
Return the tag value which is set by lua_kong_set_static_tag directive.
If there is no tag in location(http subsystems) or server(stream subsystems) block,
it will return nil.
syntax: resty.kong.log.set_log_level(level, timeout)
context: any
subsystems: http
Dynamically configures the level with a timeout for the current worker, and must be one of the Nginx log level constants.
The timeout specifies a number of seconds after which the log level will be
reset to the previous value. If timeout is 0, the log level will be reset to the
default log_level setting from Nginx configuration immediately.
If this method is called again before the timeout, the log level and timeout will be overwritten.
If we don’t pass timeout to set_log_level(), it will raise a Lua error. Back to TOC
syntax: current_level, timeout, original_level = resty.kong.log.get_log_level()
context: any
subsystems: http
Returns the current dynamic log level, remaining timeout (in seconds), and the original log level.
If the dynamic log level is not set or not active,
the timeout will be 0.
Please see Nginx log level constants
for the possible value of level.
syntax: res = resty.kong.peer_conn.get_last_peer_connection_cached()
context: balancer_by_lua
subsystems: http
This function retrieves information about whether the connection used in the previous attempt came from the upstream connection pool when the next_upstream retrying mechanism is in action.
The possible results are as follows:
false: Indicates the connection was not reused from the upstream connection pool, meaning a new connection was created with the upstream in the previous attempt.true: Indicates the connection was reused from the upstream connection pool, meaning no new connection was created with the upstream in the previous attempt.
After applying the dynamic upstream keepalive patch, Nginx's upstream module attempts to retrieve connections from the upstream connection pool for each retry. If the obtained connection is deemed unusable, Nginx considers that retry invalid and performs a compensatory retry.
Since each retry triggers the balancer_by_lua phase, the number of retries logged in Lua land during this phase may exceed the maximum limit set by set_more_tries.
Using this function in the balancer_by_lua phase allows for determining if the connection used in the previous retry was taken from the connection pool.
If the return value is true, it indicates that the connection from the pool used in the previous retry was unusable, rendering that retry void.
The value returned by this function helps in accurately assessing the actual number of new connections established with the upstream server during the retry process during the balancer_by_lua phase.
Example:
balancer_by_lua_block {
local ctx = ngx.ctx
ctx.tries = ctx.tries or {}
local tries = ctx.tries
-- update the number of tries
local try_count = #tries + 1
-- fetch the last peer connection cached
local peer_conn = require("resty.kong.peer_conn")
local last_peer_connection_cached = peer_conn.get_last_peer_connection_cached()
if try_count > 1 then
local previous_try = tries[try_count - 1]
previous_try.cached = peer_conn.get_last_peer_connection_cached()
else
tries[try_count].cached = false
end
...
}Copyright 2020-2023 Kong Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.