2.0.96

• #197: use Alias records instead of CNAMEs

TL;DR: Senza v2.0.96+ internally now manages “Alias” DNS records instead of CNAMEs. Behavior of traffic switching generally stays the same, but you will see differences in the output of DNS tools like dig or host.

The new Senza version v2.0.96+ will introduce a major change in how DNS records and traffic switching is handled:

• Route 53 DNS records are now Alias instead of CNAME records pointing to the ELB
  DNS lookups (e.g. “dig foo.myteam.zalan.do”) will no longer “reveal” the stack version as Route 53 directly returns A records (ELB IPs):

# dig output for Senza 1.0.92 with CNAMEs
foo.myteam.example.org. 20 IN CNAME foo-cd72c1-1849488195.eu-central-1.elb.amazonaws.com.
Foo-cd72c1-1849488195.eu-central-1.elb.amazonaws.com. 60 IN A 52.29.201.53
Foo-cd72c1-1849488195.eu-central-1.elb.amazonaws.com. 60 IN A 52.58.212.223
# dig output for Senza 2.0.96+ with Alias records
foo.myteam.example.org. 20 IN A 52.29.201.53
foo.myteam.example.org. 20 IN A 52.58.212.223

• "main_dns" column of senza status will now work on resolved IP address, you can use “senza status” to see whether your local DNS resolves to the right stack version (as “dig” no longer easily reveals this information)
• Senza will ask you to migrate existing DNS records from CNAME to Alias the first time you deploy with the new Senza version or update the traffic of a stack. Route53 records pointing to non-existing\deleted ELBs can't be converted and will be deleted.
• Lizzy will migrate existing DNS records from CNAME to Alias the first time you deploy a new stack or update the traffic of an existing stack. Route53 records pointing to non-existing\deleted ELBs can't be converted and will be deleted.
• ZMON AWS Agent already supports Alias records to set the “dns_traffic” property