Add some env variables to the e2e script

Add three switches (env variables) in the main e2e script, that
can be used to:
- skip setting up the test environment
- skip running the YAML based tests
- set the feature gate (this is also available as ENV var

They are useful for setting up the E2E tests in KinD clusters, as
well as generally useful for development purposes.

Signed-off-by: Andrea Frittoli <andrea.frittoli@uk.ibm.com>

Author: afrittoli

test/e2e-tests-kind.env

@@ -0,0 +1,4 @@
+SKIP_INITIALIZE=true
+PIPELINE_FEATURE_GATE=stable
+RUN_YAML_TESTS=false
+KO_DOCKER_REPO=registry.local:5000

test/e2e-tests.sh

@@ -19,9 +19,18 @@
 
 source $(git rev-parse --show-toplevel)/test/e2e-common.sh
 
+
+# Setting defaults
+PIPELINE_FEATURE_GATE=${PIPELINE_FEATURE_GATE:-stable}
+SKIP_INITIALIZE=${SKIP_INITIALIZE:="false"}
+RUN_YAML_TESTS=${RUN_YAML_TESTS:="true"}
+failed=0
+
 # Script entry point.
 
-initialize $@
+if [ "${SKIP_INITIALIZE}" != "true" ]; then
+  initialize $@
+fi
 
 header "Setting up environment"
 
@@ -49,17 +58,13 @@ function run_e2e() {
   # Run these _after_ the integration tests b/c they don't quite work all the way
   # and they cause a lot of noise in the logs, making it harder to debug integration
   # test failures.
-  go_test_e2e -tags=examples -timeout=20m ./test/ || failed=1
+  if [ "${RUN_YAML_TESTS}" == "true"]; then
+    go_test_e2e -tags=examples -timeout=20m ./test/ || failed=1
+  fi
 }
 
-if [ "$PIPELINE_FEATURE_GATE" == "" ]; then
-  set_feature_gate "stable"
-  run_e2e
-else
-  set_feature_gate "$PIPELINE_FEATURE_GATE"
-  run_e2e
-fi
-
+set_feature_gate "$PIPELINE_FEATURE_GATE"
+run_e2e
 
 (( failed )) && fail_test
 success