docker: add snippet for older kernels to CAP_SYS_ADMIN for inlet

CAP_BPF was introduced in Linux 5.8.

console/data/docs/99-changelog.md

@@ -13,13 +13,15 @@ identified with a specific icon:
 ## Unreleased
 
 This release brings a performance improvement on Linux by using per-packet
-load-balancing for incoming flows using eBPF. Previously, exporters may be tied
-to one worker, triggering packet loss.
+load-balancing for incoming flows using eBPF. Previously, exporters were tied to
+one worker, triggering packet loss despite many workers available. This requires
+Linux 5.8+ (support of `CAP_BPF`). For older kernels, have a look at
+`docker/docker-compose-local.yaml`.
 
 - 🩹 *inlet*: fix `akvorado_inlet_flow_input_udp_in_dropped_packets_total` metric
 - 🩹 *console*: fix completion tooltip being wrapped with Firefox
 - 💥 *config*: stop shipping demo exporter configurations from the orchestrator
-- 🌱 *inlet*: load-balance incoming UDP packets to all workers using eBPF on Linux
+- 💥 *inlet*: load-balance incoming UDP packets to all workers using eBPF on Linux
 - 🌱 *outlet*: be more aggressive when increasing the number of workers
 - 🌱 *outlet*: cap the number of workers to the number of Kafka partitions
 - 🌱 *console*: add `auth`→`logout-url` and `auth`→`avatar-url` to configure

docker/docker-compose-local.yml

@@ -86,7 +86,6 @@
 #       - traefik.http.middlewares.sso.forwardauth.trustForwardHeader=true
 #       - traefik.http.middlewares.sso.forwardauth.authResponseHeaders=X-Forwarded-User,X-Forwarded-Displayname,X-Authenticated-User
 
-
 # If you don't want to expose Kafka-UI and Traefik on the public endpoints, uncomment this block.
 
 # services:
@@ -110,3 +109,10 @@
 #       config:
 #         - subnet: 2001:db8::/64
 #           gateway: 2001:db8::1
+
+# If you are running an older kernel than Linux 5.8, you need to uncomment the following block:
+
+# services:
+#   akvorado-inlet:
+#     cap_add: !override
+#       - SYS_ADMIN # BPF capability is supported only from Linux 5.8