Implement a workaround for the IPv6 issue

We observed intermittent failures during deployment, due to Go resolving Google API domains into IPv6 addresses, even though the Cloud Shell environment has IPv6 disabled.

Until the Go issue (golang/go#25321) has been resolved, we have to patch the `/etc/hosts` file on the Cloud Shell machine to ensure that these domains are resolved using IPv4 only.

PiperOrigin-RevId: 495598377

.gitignore

@@ -2,6 +2,7 @@
 *.swp
 __pycache__
 *.pyc
+crmint.egg-info/
 
 # System Files
 .DS_Store

cli/.gitignore

@@ -1,2 +1,4 @@
 *.egg-info
 stages/*.py
+build/
+dist/

cli/commands/cloud.py

@@ -131,6 +131,20 @@ def terraform_switch_workspace(stage: shared.StageContext,
         debug=debug)
 
 
+def patch_etc_hosts(debug: bool = False) -> None:
+  """Workaround to avoid Terraform to use IPv6 addresses."""
+  cmd = 'bash scripts/force_ipv4_addresses.sh'
+  shared.execute_command(
+      'Patch /etc/hosts to force IPv4', cmd, cwd='./cli', debug=debug)
+
+
+def unpatch_etc_hosts(debug: bool = False) -> None:
+  """Restores the `/etc/hosts` file."""
+  cmd = 'sudo cp /etc/hosts.backup /etc/hosts'
+  shared.execute_command(
+      'Restore /etc/hosts', cmd, cwd='./cli', debug=debug)
+
+
 def terraform_init(debug: bool = False) -> bool:
   """Runs the Terraform init command."""
   cmd = 'terraform init -upgrade'
@@ -352,6 +366,7 @@ def setup(stage_path: Union[None, str], debug: bool) -> None:
     sys.exit(1)
 
   # Switches workspace.
+  patch_etc_hosts(debug=debug)
   terraform_init(debug=debug)
   terraform_switch_workspace(stage, debug=debug)
 
@@ -363,6 +378,7 @@ def setup(stage_path: Union[None, str], debug: bool) -> None:
   terraform_plan(stage, debug=debug)
   configuration_summary_from_plan(debug=debug)
   terraform_apply(debug=debug)
+  unpatch_etc_hosts(debug=debug)
   click.echo(click.style('Done.', fg='magenta', bold=True))
 
 

cli/commands/cloud_tests.py

@@ -201,6 +201,7 @@ def test_validates_stdout_without_vpc(self):
         textwrap.dedent("""\
             >>>> Setup
                  Project ID found: dummy_project_with_vpc
+            ---> Patch /etc/hosts to force IPv4 ✓
             ---> Initialize Terraform ✓
             ---> List Terraform workspaces ✓
             ---> Create new Terraform workspace: dummy_project_with_vpc ✓
@@ -215,6 +216,7 @@ def test_validates_stdout_without_vpc(self):
                  Cloud Run Service IAM Member \\(3\\)
                  (.|\\n)*
             ---> Apply Terraform plan \\(~10min\\) ✓
+            ---> Restore /etc/hosts ✓
             Done.
             """)
     )

cli/scripts/force_ipv4_addresses.sh

@@ -0,0 +1,59 @@
+#!/bin/bash
+#
+# IPv6 is disabled in Google Cloud Shell, though the DNS resolution in Go
+# does not always comply with this setting and from time to time resolves to
+# an IPv6 address.
+#
+# The following workaround as been described proposes, waiting for the Go team
+# to solve this properly (https://github.com/golang/go/issues/25321).
+#
+# See: https://github.com/hashicorp/terraform-provider-google/issues/6782
+#
+
+# Checks that we run inside a Google VM.
+GMETADATA_ADDR=`dig +short metadata.google.internal`
+if [[ "${GMETADATA_ADDR}" == "" ]]; then
+  echo "Not on a Google VM, no need to patch the /etc/hosts file."
+  exit 0
+fi
+
+# Backup existing /etc/hosts.
+if [ ! -f /etc/hosts.backup ]; then
+  sudo cp /etc/hosts /etc/hosts.backup
+fi
+
+read -r -d '' APIS << EOM
+aiplatform.googleapis.com
+analytics.googleapis.com
+analyticsadmin.googleapis.com
+analyticsreporting.googleapis.com
+cloudbuild.googleapis.com
+cloudresourcemanager.googleapis.com
+cloudscheduler.googleapis.com
+compute.googleapis.com
+container.googleapis.com
+googleapis.com
+iam.googleapis.com
+logging.googleapis.com
+monitoring.googleapis.com
+pubsub.googleapis.com
+secretmanager.googleapis.com
+servicenetworking.googleapis.com
+sqladmin.googleapis.com
+storage-api.googleapis.com
+storage-component.googleapis.com
+storage.googleapis.com
+www.googleapis.com
+EOM
+
+# Restores the backup content.
+sudo sh -c "cat /etc/hosts.backup > /etc/hosts"
+
+# Adds IPv4 addresses for each Google Cloud API.
+sudo sh -c "echo -e '\n# Forcing IPv4 to workaround a Go issue: https://github.com/golang/go/issues/25321' >> /etc/hosts"
+for name in $APIS
+do
+  ipv4=$(getent ahostsv4 "$name" | head -n 1 | awk '{ print $1 }')
+  sudo sh -c "echo '$ipv4 $name' >> /etc/hosts"
+  echo "Forced IPv4 for $name: $ipv4"
+done