delete_stacks.sh

#!/usr/bin/env bash

# generic script for removing cloudformation stacks and old CNAME records where the pull request is closed

# set the repo name to be the name of the repo this is running in
REPO_NAME=eps-prescription-status-update-api

# this should be a regex used in jq command that parses the output from aws cloudformation list-stacks and just captures stacks we are interested in
CAPTURE_REGEX="^psu-(cdk-)?pr-([0-9]+)(-sandbox|-stateful)?$"

# TODO: no longer needed?
# this should be a regex that is used to get the pull request id from the cloud formation stack name
# this is used in a replace command to replace the stack name so what is left is just the pull request id
#PULL_REQUEST_STACK_REGEX=psu-pr-

CNAME_QUERY=psu-pr-

main() {
  delete_cloudformation_stacks
  delete_cname_records
}

delete_cloudformation_stacks() {
  echo "checking cloudformation stacks"
  echo
  ACTIVE_STACKS=$(aws cloudformation list-stacks | jq -r --arg CAPTURE_REGEX "${CAPTURE_REGEX}" '.StackSummaries[] | select ( .StackStatus != "DELETE_COMPLETE" ) | select( .StackName | capture($CAPTURE_REGEX) ) | .StackName ')

  mapfile -t ACTIVE_STACKS_ARRAY <<< "$ACTIVE_STACKS"

  for i in "${ACTIVE_STACKS_ARRAY[@]}"
  do 
    echo "Checking if stack $i has open pull request"
    # Extract PR number from stack names like psu-pr-123, psu-pr-123-sandbox,
    # psu-cdk-pr-123, or psu-cdk-pr-123-stateful
    PULL_REQUEST=$(echo "${i}" | sed 's/.*-pr-//' | sed 's/-.*//')
    echo "Checking pull request id ${PULL_REQUEST}"
    URL="https://api.github.com/repos/NHSDigital/${REPO_NAME}/pulls/${PULL_REQUEST}"
    RESPONSE=$(curl "${URL}" 2>/dev/null)
    STATE=$(echo "${RESPONSE}" | jq -r .state)
    if [ "$STATE" == "closed" ]; then
      echo "** going to delete stack $i as state is ${STATE} **"
      aws cloudformation delete-stack --stack-name "${i}"
      echo "** Sleeping for 60 seconds to avoid 429 on delete stack **"
      sleep 60
    else
      echo "not going to delete stack $i as state is ${STATE}"
    fi
  done
}

delete_cname_records() {
  HOSTED_ZONE_ID=$(aws route53 list-hosted-zones-by-name --dns-name dev.eps.national.nhs.uk. | jq -r ".HostedZones[0] | .Id")
  CNAME_RECORDS=$(aws route53 list-resource-record-sets --hosted-zone-id "${HOSTED_ZONE_ID}" \
    --query "ResourceRecordSets[?Type == 'CNAME' && contains(Name, '${CNAME_QUERY}')]" \
    | jq -r " .[] | .Name")

  mapfile -t CNAME_RECORDS_ARRAY <<< "$CNAME_RECORDS"

  for i in "${CNAME_RECORDS_ARRAY[@]}"
  do
    echo "Checking if CNAME record $i has open pull request"

    PULL_REQUEST=$(echo "$i" | grep -Po '(?<=-pr-)\d+')
    echo "Checking pull request id ${PULL_REQUEST}"
    URL="https://api.github.com/repos/NHSDigital/${REPO_NAME}/pulls/${PULL_REQUEST}"
    RESPONSE=$(curl --url "${URL}" --header "Authorization: Bearer ${GITHUB_TOKEN}" 2>/dev/null)
    STATE=$(echo "${RESPONSE}" | jq -r .state)
    if [ "$STATE" == "closed" ]; then
      echo "** going to delete CNAME record $i as state is ${STATE} **"
      record_set=$(aws route53 list-resource-record-sets --hosted-zone-id "${HOSTED_ZONE_ID}" \
        --query "ResourceRecordSets[?Name == '$i']" --output json | jq .[0])

      jq -n --argjson record_set "${record_set}" \
          '{Changes: [{Action: "DELETE", ResourceRecordSet: $record_set}]}' > /tmp/payload.json

      aws route53 change-resource-record-sets --hosted-zone-id "${HOSTED_ZONE_ID}" --change-batch file:///tmp/payload.json

      echo "CNAME record $i deleted"
      else
        echo "not going to delete CNAME record $i as state is ${STATE} **"
      fi
  done
}

main