Let me introduce the script swap-dns-records.sh used to swap the Route53 DNS records of production and staging environments. The script uses couple of new utility scripts and I shall present them too.
Once we create a AWS Elastic Beanstalk staging environment, the application becomes available for testing. After we are satisfied with the testing and wish to move it to the production we could do that using the script swap-dns-records.sh.
Let us say when we create a new staging environment, two Route53 DNS entries get created for example, myAppName-staging.myDomainName.com and ec2.myAppName-staging.myDomainName.com. Similarly the production environment could have its entries as myAppName-production.myDomainName.com and ec2.myAppName-production.myDomainName.com. Route53 account could also have top level entries such as myDomainName.com and www.myDonainName.com and both could be AliasTarget records pointing to the main production record. At hudku.com this is the kind of setup we have. The advantage is if we change the Load Balancer URL of the only production entry then both the top level entries would reflect that change.
Using the script swap-dns-records.sh we try to swap the production and staging entries resulting in staging becoming production and the production becomes staging. In case we notice any problem with the new application and we wish to revert, we just need to run this script again to do the swap once more.
Let us have our directory structure. The “deployment” directory is nicely getting populated. You can expand the “util” directory to see the long list of utility scripts. We are not too far away from reaching our destination of completing the Customization of AWS Elastic Beanstalk, at the end of which I shall provide a zip file that could be downloaded and would contain all the scripts along with a detailed step by step instructions about its usage. So please stay tuned.
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Coming back to our current script, it performs the swap of Route53 entries using the utility script route53-swap-dns-records.sh which gets called twice, once to swap the application URL and then to swap the EC2 instance URL.
The script also swaps the CNAME records of staging and production environments so that the CNAME used by Elastic Beanstalk also properly reflects which is the production environment and which one is staging. To perform the CNAME swap, we need the Beanstalk environment names of both the environments. The script calls another utility script route53-get-alias-target-dns.sh
to first obtain the Load Balancer URL of an environment using which it obtains the name of the environment by calling our utility script elastic-beanstalk-get-env-name-from-elb-url.sh. Once the names of the environments are available, the script calls elastic-beanstalk-swap-environment-cnames, the beanstalk command line utility provided by Amazon.
In this post I have also included another utility script route53-get-hosted-zone-id.sh which obtains the Route53 hosted zone id given the zone name in a different manner. Instead of using the utility dnscurl.pl, it uses the utlity route53 which is installed by Beanstalk.
Here is the source code of swap-dns-records.sh.
#!/bin/bash # Execute "export DEBUG=1" to debug this script. # Set value to 2 to debug this script and the scripts called within this script. # Set value to 3,4,5 and so on to increase the nesting level of the scripts to be debugged. [[ $DEBUG -gt 0 ]] && set -x; export DEBUG=$(($DEBUG - 1)) # # Swaps Route53 DNS records of production and staging Elastic Beanstalk environments # dnsProduction=$($ELASTICBEANSTALK_APP_SCRIPT_DIR/util/route53-get-alias-target-dns.sh $ROUTE53_RR_PRODUCTION_NAME) dnsStaging=$($ELASTICBEANSTALK_APP_SCRIPT_DIR/util/route53-get-alias-target-dns.sh $ROUTE53_RR_STAGING_NAME) envNameProduction=$($ELASTICBEANSTALK_APP_SCRIPT_DIR/util/elastic-beanstalk-get-env-name-from-elb-url.sh $dnsProduction) envNameStaging=$($ELASTICBEANSTALK_APP_SCRIPT_DIR/util/elastic-beanstalk-get-env-name-from-elb-url.sh $dnsStaging) # Swap Production and Staging Route53 records $ELASTICBEANSTALK_APP_SCRIPT_DIR/util/route53-swap-dns-records.sh $AWS_ACCOUNT_KEY_NAME $ROUTE53_RR_PRODUCTION_NAME $ROUTE53_RR_STAGING_NAME # Swap Route53 EC2 CNAME records $ELASTICBEANSTALK_APP_SCRIPT_DIR/util/route53-swap-dns-records.sh $AWS_ACCOUNT_KEY_NAME ec2.$ROUTE53_RR_PRODUCTION_NAME ec2.$ROUTE53_RR_STAGING_NAME # Swap Elastic Beanstalk CNAME records echo "Swapping Elastic Beanstalk environment URLs of production $envNameProduction and staging $envNameStaging" elastic-beanstalk-swap-environment-cnames -s $envNameProduction -d $envNameStaging
#!/bin/bash
# Execute "export DEBUG=1" to debug this script.
# Set value to 2 to debug this script and the scripts called within this script.
# Set value to 3,4,5 and so on to increase the nesting level of the scripts to be debugged.
[[ $DEBUG -gt 0 ]] && set -x; export DEBUG=$(($DEBUG - 1))
#
# Swaps the specified Route53 DNS entry records
#
display_usage()
{
echo -e "\nUsage: route53-swap-dns-records awsAccountKeyName dnsEntryName1 dnsEntryName2 [www]\n"
}
# Exactly one argument should be supplied
if [ ! $# == 3 ] && [ ! $# == 4 ]; then
display_usage
exit 2
fi
awsAccountKeyName=$1
dnsEntryName1=$2
dnsEntryName2=$3
prefixName=$4
# Extract host name from the dns entry name
hostName=$(echo $dnsEntryName1 | grep -o "[^\.]*\.[^\.]*\.$")
# dnscurl common options
optionsDNSCurl="-- -s -H \"Content-Type: text/xml; charset=UTF-8\""
# Route53 API settings
urlRoute53API="https://route53.amazonaws.com/2012-02-29"
# Get Route53 HostedZoneId
allHostedZones=$(dnscurl.pl --keyname $awsAccountKeyName $optionsDNSCurl -X GET $urlRoute53API/hostedzone 2>/dev/null)
hostNameSearch="ListHostedZonesResponse/HostedZones/HostedZone[Name=\"$hostName\"]/Id"
hostedZoneId=$(echo $allHostedZones | xpath $hostNameSearch 2>/dev/null | awk -F'[<|>]' '/Id/{print $3}' | cut -d/ -f3)
if ([ -z $hostedZoneId ]) then
echo "Error: Failed to obtain hosted zone id for '$hostName' in Route53"
exit 1
fi
# Obtain all the resource record sets for the hosted zone id
allRecords=$(dnscurl.pl --keyname $awsAccountKeyName $optionsDNSCurl -X GET $urlRoute53API/hostedzone/$hostedZoneId/rrset 2>/dev/null)
# Obtain AliasTarget records
dnsRecordSearch="ListResourceRecordSetsResponse/ResourceRecordSets/ResourceRecordSet[Name=\"$dnsEntryName1\"]"
dnsRecord1=$(echo $allRecords | xpath $dnsRecordSearch 2>/dev/null)
dnsRecordSearch="ListResourceRecordSetsResponse/ResourceRecordSets/ResourceRecordSet[Name=\"$dnsEntryName2\"]"
dnsRecord2=$(echo $allRecords | xpath $dnsRecordSearch 2>/dev/null)
# Check if we have both the records that have to be swapped
if ([ -z $dnsRecord1 ]) then
echo "Could not find DNS record for $dnsEntryName1."
exit 1
fi
if ([ -z $dnsRecord2 ]) then
echo "Could not find DNS record for $dnsEntryName2."
exit 1
fi
newRecord1=$(echo $dnsRecord1 | sed "s|<name>$dnsEntryName1</name>|<name>$dnsEntryName2</name>|g")
newRecord2=$(echo $dnsRecord2 | sed "s|<name>$dnsEntryName2</name>|<name>$dnsEntryName1</name>|g")
# Check if www prefix also has to be processed
if ([ ! -z $prefixName ]) then
dnsRecord3=$(echo $dnsRecord1 | sed "s|<name>$dnsEntryName1</name>|<name>www.$dnsEntryName1</name>|g")
dnsRecord4=$(echo $dnsRecord2 | sed "s|<name>$dnsEntryName2</name>|<name>www.$dnsEntryName2</name>|g")
newRecord3=$(echo $dnsRecord3 | sed "s|<name>www.$dnsEntryName1</name>|<name>www.$dnsEntryName2</name>|g")
newRecord4=$(echo $dnsRecord4 | sed "s|<name>www.$dnsEntryName2</name>|<name>www.$dnsEntryName1</name>|g")
dnsRecord3=$(echo "<change><action>DELETE</action>$dnsRecord3</change>")
dnsRecord4=$(echo "<change><action>DELETE</action>$dnsRecord4</change>")
newRecord3=$(echo "<change><action>CREATE</action>$newRecord3</change>")
newRecord4=$(echo "<change><action>CREATE</action>$newRecord4</change>")
fi
# Generate a timestamp to mark the Route53 transaction
timestamp=$(date)
# Create a temporary XML file
xmlTmp=$(mktemp)
# Set up the xml with delete and create commands
echo "Swapping the DNS records of $dnsEntryName1 and $dnsEntryName2"
cat <<ROUTE53-XML > $xmlTmp
<?xml version="1.0" encoding="UTF-8"?>
<ChangeResourceRecordSetsRequest xmlns="$urlRoute53APIDoc">
<ChangeBatch>
<Comment>Update Record for $dnsEntryName at $timestamp</Comment>
<Changes>
<Change>
<Action>DELETE</Action>
$dnsRecord1
</Change>
<Change>
<Action>DELETE</Action>
$dnsRecord2
</Change>
$dnsRecord3
$dnsRecord4
<Change>
<Action>CREATE</Action>
$newRecord1
</Change>
<Change>
<Action>CREATE
$newRecord2
</Change>
$newRecord3
$newRecord4
</Changes>
</ChangeBatch>
</ChangeResourceRecordSetsRequest>
ROUTE53-XML
# POST the XML containing Route53 actions
route53Response=$(dnscurl.pl --keyname $awsAccountKeyName $optionsDNSCurl -X POST --upload-file $xmlTmp $urlRoute53API/hostedzone/$hostedZoneId/rrset 2>/dev/null)
# Delete the temporary XML file
rm -f $xmlTmp
# Obtain the response and check its status
route53ResponseStatus=$(echo $route53Response | xpath 'ChangeResourceRecordSetsResponse/ChangeInfo/Status' 2>/dev/null | awk -F'[<|>]' '/Status/{print $3}' | cut -d/ -f3)
if ([ "$route53ResponseStatus" != "PENDING" ]) then
echo "Error: Expected PENDING status from Route53, but received some other status."
echo $route53Response
exit 1
fi
# Obtain Route53 transaction ID
route53ResponseID=$(echo $route53Response | xpath 'ChangeResourceRecordSetsResponse/ChangeInfo/Id' 2>/dev/null | awk -F'[<|>]' '/Id/{print $3}' | cut -d/ -f3)
echo "Received response status ID $route53ResponseID with status $route53ResponseStatus"
echo "Successfully swapped Route53 DNS records."
route53-get-alias-target-dns.sh
#!/bin/bash
# Execute "export DEBUG=1" to debug this script.
# Set value to 2 to debug this script and the scripts called within this script.
# Set value to 3,4,5 and so on to increase the nesting level of the scripts to be debugged.
[[ $DEBUG -gt 0 ]] && set -x; export DEBUG=$(($DEBUG - 1))
#
# Retrieves the value of the AliasTarget record for the specified Route53 DNS entry name
#
display_usage()
{
echo -e "\nUsage: $0 route53_RR_Name\n"
}
# Check argument count
if [ ! $# == 1 ]; then
display_usage
exit 2
fi
dnsEntryName=$1
awsAccountKeyName=$AWS_ACCOUNT_KEY_NAME
# Extract host name from the dns entry name
hostName=$(echo $dnsEntryName | grep -o "[^\.]*\.[^\.]*\.$")
# dnscurl common options
optionsDNSCurl="-- -s -H \"Content-Type: text/xml; charset=UTF-8\""
# Route53 API settings
urlRoute53API="https://route53.amazonaws.com/2012-02-29"
# Get Route53 HostedZoneId
allHostedZones=$(dnscurl.pl --keyname $awsAccountKeyName $optionsDNSCurl -X GET $urlRoute53API/hostedzone 2>/dev/null)
hostNameSearch="ListHostedZonesResponse/HostedZones/HostedZone[Name=\"$hostName\"]/Id"
hostedZoneId=$(echo $allHostedZones | xpath $hostNameSearch 2>/dev/null | awk -F'[<|>]' '/Id/{print $3}' | cut -d/ -f3)
if ([ -z $hostedZoneId ]) then
exit 1
fi
# Obtain all the resource record sets for the hosted zone id
allRecords=$(dnscurl.pl --keyname $awsAccountKeyName $optionsDNSCurl -X GET $urlRoute53API/hostedzone/$hostedZoneId/rrset 2>/dev/null)
# Obtain the value of the DNS AliasTarget
dnsNameSearch="ListResourceRecordSetsResponse/ResourceRecordSets/ResourceRecordSet[Name=\"$dnsEntryName\"]/AliasTarget/DNSName"
dnsName=$(echo $allRecords | xpath $dnsNameSearch 2>/dev/null | awk -F'[<|>]' '/DNSName/{print $3}' | cut -d/ -f3 | sed 's/.$//')
if ([ -z $dnsName ]) then
exit 1
fi
echo $dnsName
#!/bin/bash
# Execute "export DEBUG=1" to debug this script.
# Set value to 2 to debug this script and the scripts called within this script.
# Set value to 3,4,5 and so on to increase the nesting level of the scripts to be debugged.
[[ $DEBUG -gt 0 ]] && set -x; export DEBUG=$(($DEBUG - 1))
#
# Retrieves the Hosted Zone Id of the specified Route53 zone using route53 command line utility
#
display_usage()
{
echo -e "\nUsage: $0 hostedZoneName\n"
}
# Exactly one argument should be supplied
if [ ! $# == 1 ]; then
display_usage
exit 2
fi
hostedZoneName=$1
route53HostedZoneID=$(route53 ls | sed -n -e '/'"$hostedZoneName"'/{g;1!p;};h' | awk '{print $3}')
if ([ -z $route53HostedZoneID ]) then
echo "Could not find zone '$hostedZoneName' in route 53"
exit 1
fi
echo $route53HostedZoneID