[3scale_batcher] Introduce APICAST_POLICY_BATCHER_SHARED_MEMORY_SIZE

In some cases, the batcher policy will run out of storage space (batched_reports)
and cause metrics to not being reported. This commit adds a new environment
variable to configure the batcher policy shared memory storage size

CHANGELOG.md

@@ -55,6 +55,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Added `APICAST_CLIENT_REQUEST_HEADER_BUFFERS` variable to allow configure of the NGINX `client_request_header_buffers` directive: [PR #1446](https://github.com/3scale/APIcast/pull/1446), [THREESCALE-10164](https://issues.redhat.com/browse/THREESCALE-10164)
 
+Added `APICAST_POLICY_BATCHER_SHARED_MEMORY_SIZE` variable to allow configure batcher policy share memory size. [PR #1452](https://github.com/3scale/APIcast/pull/1452), [THREESCALE-9537](https://issues.redhat.com/browse/THREESCALE-9537)
+
 ## [3.14.0] 2023-07-25
 
 ### Fixed

doc/parameters.md

@@ -517,6 +517,13 @@ Sets the maximum number and size of buffers used for reading large client reques
 The format for this value is defined by the [`large_client_header_buffers` NGINX
 directive](https://nginx.org/en/docs/http/ngx_http_core_module.html#large_client_header_buffers)
 
+### `APICAST_POLICY_BATCHER_SHARED_MEMORY_SIZE`
+
+**Default:** 20m
+**Value:** string
+
+Sets the maximum size of shared memory used by batcher policy.
+
 ### `OPENTELEMETRY`
 
 This environment variable enables NGINX instrumentation using OpenTelemetry tracing library.

gateway/http.d/shdict.conf

@@ -6,5 +6,5 @@ lua_shared_dict limiter 1m;
 # This is not ideal, but they'll need to be here until we allow policies to
 # modify this template.
 lua_shared_dict cached_auths 20m;
-lua_shared_dict batched_reports 20m;
+lua_shared_dict batched_reports {{env.APICAST_POLICY_BATCHER_SHARED_MEMORY_SIZE | default: "20m"}};
 lua_shared_dict batched_reports_locks 1m;