feat: Replace default gateway to allow login

The instance creation with internal port attached was causing issues
with login because the default gateway was set to internal network
gateway. This will only allow login via headnode but not the host.
This commit will fix that issue by giving a way to define the gw ip
for default route.

.gitlab-ci.yml

@@ -149,6 +149,7 @@ deploy_http_proxy_node:
       cat > user_data.txt <<EOF
       #!/bin/bash
       echo "$DEV_KEY" >> /root/.ssh/authorized_keys
+      ip route replace default via ${DEFAULT_GATEWAY_IP} dev eth0
       git clone ${CI_REPOSITORY_URL} /tmp/${CI_PROJECT_NAME}
       cd /tmp/${CI_PROJECT_NAME}
       git checkout ${CI_COMMIT_REF_NAME}
@@ -197,6 +198,7 @@ deploy_ssh_proxy_node:
       cat > user_data.txt <<EOF
       #!/bin/bash
       echo "$DEV_KEY" >> /root/.ssh/authorized_keys
+      ip route replace default via ${DEFAULT_GATEWAY_IP} dev eth0
       git clone ${CI_REPOSITORY_URL} /tmp/${CI_PROJECT_NAME}
       cd /tmp/${CI_PROJECT_NAME}
       git checkout ${CI_COMMIT_REF_NAME}