Add MySQL Router connection limit on bootstrap_rw

Inject max_connections=40 into the routing:bootstrap_rw section of the
generated mysqlrouter.conf after bootstrap. Prevents a single misbehaving
client from consuming all MySQL server connections and starving cluster
operations (health checks, replication, admin).

Closes #82

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: szachovy

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Dependabot updates for `github-actions` and `terraform` ecosystems. (#29)
 * CI workflow to build and push service images to GitHub Container Registry on master merge. (#97)
 * Pull-first with local build fallback for container images during deployment. (#97)
+* MySQL Router max_connections=40 on bootstrap_rw to reserve connections for cluster operations. (#82)
 
 ### Changed
 

services/mysql-mgmt/docker_compose.yml

@@ -71,6 +71,8 @@ services:
             "/opt/default/mysql_router_certificate.pem" \
           --client-ssl-key \
             "/opt/default/mysql_router_key.pem"
+        sed -i 's/\[routing:bootstrap_rw\]/[routing:bootstrap_rw]\nmax_connections=40/' \
+            /opt/default/mysql_router/mysqlrouter.conf
         mysqlsh \
           --login-path="${PRIMARY_MYSQL_NODE}" --sql \
           --execute="DROP USER 'superset'@'$(mysqlsh --python --execute "exec(open('/opt/interfaces.py').read())")';"