TEST/MEDIUM: e2e: bump the default HAProxy version to 2.6

Also add HAProxy 2.6 to the Gitlab CI and update the README.

Author: oliwer

.gitlab-ci.yml

@@ -129,3 +129,9 @@ HAProxy_2_5:
     matrix:
       - TESTPART: [ "1/2", "2/2" ]
         HAPROXY_VERSION: "2.5"
+HAProxy_2_6:
+  extends: .e2e
+  parallel:
+    matrix:
+      - TESTPART: [ "1/2", "2/2" ]
+        HAPROXY_VERSION: "2.6"

e2e/README.md

@@ -62,7 +62,7 @@ $ E2E_PORT=8081 make e2e
 
 #### HAProxy version
 
-By default, test suite is running against HAProxy 2.3 release: this can be
+By default, test suite is running against HAProxy 2.6 release: this can be
 configured using the environment variable `HAPROXY_VERSION`.
 
 ```bash

e2e/run.bash

@@ -18,7 +18,7 @@ set -eo pipefail
 
 export BASE_PATH="/v2"
 
-HAPROXY_VERSION=${HAPROXY_VERSION:-2.1}
+HAPROXY_VERSION=${HAPROXY_VERSION:-2.6}
 DOCKER_BASE_IMAGE="${DOCKER_BASE_IMAGE:-haproxytech/haproxy-alpine}:${HAPROXY_VERSION}"
 DOCKER_CONTAINER_NAME="dataplaneapi-e2e"
 export DOCKER_CONTAINER_NAME