README
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gocql-ec2
The gocql_ec2 package provides Amazon EC2 related functionality for the
gocql cassandra driver. Currently this is limited to providing address translation
support for multi-region cassandra ring setups, but who knows what else might be useful. Plus, gocql_ec2 is a much
more succinct package name than gocql_ec2_address_translator.
Multi-Region Address Translator
The EC2MultiRegionAddressTranslator will attempt to resolve any peer's broadcast address to its private-ip.
This works by doing a reverse lookup on the broadcast address -- which should be its public-ip -- then doing an address
lookup for any hostname resulting from the reverse lookup. Within the same ec2 region, this will translate the public-ip
into a private-ip; outside of the peer's ec2 region, only the public-ip will be returned.
This is typically done to save on costs. It's also useful when your "ring masters" disable public-ip access for connections coming from inside the same network (which they are doing to force you to save on costs).
Usage
Configuring gocql to use this translator is straight-forward; just configure the ClusterConfig.AddressTranslator:
cluster := gocql.NewCluster("node1", "node2")
cluster.AddressTranslator = gocql_ec2.EC2MultiRegionAddressTranslator()
// ...
session := cluster.NewSession()
Testing
Unit tests:
go test github.com/signal/gocql_ec2/...
Integration tests:
./integration.sh ${GOPATH}
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func EC2MultiRegionAddressTranslator ¶
func EC2MultiRegionAddressTranslator() gocql.AddressTranslator
EC2MultiRegionAddressTranslator will do a reverse DNS lookup on the address provided, then do a DNS lookup on the first hostname found in order to potentially get the private IP of the given address. If no results are found in either lookup, the given address is returned. Port is always returned unchanged. Build with the gocql_debug tag to see address translation at work.
Source Files