test/system: use a random port for the local Docker registry

Hard-coding the port to 50000 can cause intermittent failures when the
port happens to already be in use, and also prevents running the test
suite more than once at the same time.

Let Podman pick a random available port and persist it to a file so test
processes in the same run can find it.

Signed-off-by: Rolv Apneseth <rolv.apneseth@gmail.com>

Author: Rolv-Apneseth

test/system/libs/helpers.bash

@@ -31,8 +31,12 @@ readonly ROOTLESS_PODMAN_RUNROOT_DIR="$BATS_SUITE_TMPDIR/runroot"
 readonly DOCKER_REG_ROOT="$BATS_SUITE_TMPDIR/docker-registry-root"
 readonly DOCKER_REG_CERTS_DIR="$BATS_SUITE_TMPDIR/certs"
 readonly DOCKER_REG_AUTH_DIR="$BATS_SUITE_TMPDIR/auth"
-readonly DOCKER_REG_URI="localhost:50000"
 readonly DOCKER_REG_NAME="docker-registry"
+# Store the registry URI in a file so that loading this script from different
+# test processes will still use the same URI for the same test suite run. The
+# contents of the file are set when setting up the local Docker registry.
+readonly DOCKER_REG_URI_FILE="$BATS_SUITE_TMPDIR/docker-reg-uri"
+DOCKER_REG_URI="$(cat "$DOCKER_REG_URI_FILE" 2>/dev/null || echo "")"
 
 # Podman and Toolbx commands to run
 readonly TOOLBX="${TOOLBX:-$(command -v toolbox)}"
@@ -166,12 +170,6 @@ function _setup_docker_registry() {
     -out "${DOCKER_REG_CERTS_DIR}"/domain.crt
   assert_success
 
-  # Add certificate to Podman's trusted certificates (rootless)
-  run mkdir -p "$HOME"/.config/containers/certs.d/"${DOCKER_REG_URI}"
-  assert_success
-  run cp "${DOCKER_REG_CERTS_DIR}"/domain.crt "$HOME"/.config/containers/certs.d/"${DOCKER_REG_URI}"/domain.crt
-  assert_success
-
   # Create a registry user
   # username: user; password: user
   run mkdir -p "${DOCKER_REG_AUTH_DIR}"
@@ -197,13 +195,25 @@ function _setup_docker_registry() {
     --env REGISTRY_HTTP_TLS_KEY=/certs/domain.key \
     --name "${DOCKER_REG_NAME}" \
     --privileged \
-    --publish 50000:5000 \
+    --publish 5000 \
     --rm \
     --volume "${DOCKER_REG_AUTH_DIR}":/auth \
     --volume "${DOCKER_REG_CERTS_DIR}":/certs \
     "${IMAGES[docker-reg]}"
   assert_success
 
+  # Determine the randomly assigned host port and persist the DOCKER_REG_URI to a file
+  local docker_reg_port
+  docker_reg_port="$(podman --root "${DOCKER_REG_ROOT}" port "${DOCKER_REG_NAME}" 5000)"
+  DOCKER_REG_URI="localhost:${docker_reg_port##*:}"
+  echo "$DOCKER_REG_URI" > "$DOCKER_REG_URI_FILE"
+
+  # Add certificate to Podman's trusted certificates (rootless)
+  run mkdir -p "$HOME"/.config/containers/certs.d/"${DOCKER_REG_URI}"
+  assert_success
+  run cp "${DOCKER_REG_CERTS_DIR}"/domain.crt "$HOME"/.config/containers/certs.d/"${DOCKER_REG_URI}"/domain.crt
+  assert_success
+
   _wait_for_docker_registry
 
   run podman login \