Raft Starter

This project uses the Hashicorp Raft implementation to easily and robustly start a new service.

It is intentionally minimalistic and it was based on the example found at https://github.com/otoolep/hraftd with some improvements out of which these are the most notable:

• Switched to cluster defintion in advance by specifiying peers (handy in Kubernetes)
• Removed all join functionality as it was not needed when knowing peers in advance
• Reading env vars instead of program arguments (allows for easier customization while ran in Kubernetes)
• Added proper defaults for all configuration variables
  • NODE_ID is by default the system hostname (very handy when ran in Kubernetes)
  • STATE_DIR defaults to /tmp/<NODE_ID>
  • KV_STORE defaults to boltdb but can be also memory if you need more speed at the price of not storing your data at all on disk
  • HTTP_ADDR defaults to 0.0.0.0
  • HTTP_PORT defaults to 11000
  • RAFT_ADDR defaults to 0.0.0.0
  • RAFT_PORT defaults to 12000
  • RAFT_ADVERTISE_ADDR defaults to the IPV4 which is obtained from resolving the system hostname (also handy when ran in Kubernetes)
  • RAFT_ADVERTISE_PORT defaults be the same as RAFT_PORT
  • PEERS of the form node1@10.1.1.1:12000,node2@10.1.1.2:12000,... defaults to be <NODE_ID>@<RAFT_ADVERTISE_ADDR>:<RAFT_ADVERTISE_PORT> which sets up a one node cluster
• All these defaults mean that you can run a single node without any environment or argument configuration
• State directory is not used for snapshots when selecting the memory key value store
• Storing the key values as map[string]interface{} instead of map[string]string
  • When retrieving an inexistent key it returns JSON null instead of ""
  • Supports numbers
  • Supports arrays
  • Supports dictionaries
• Separated each responsibility in one Go file
• Cleanly commented main.go
• Made sure all possible errors are accounted for
• Added correct signal support
• Used the Hashicorp logger
• Added API to the Store and an example of how to detect Raft state changes
• Added Procfile for easier debug using goreman which is meant to be run like this:
  go build -o ./tmp/app && goreman start
• Added example of how to run it in Kubernetes:
  ./_scripts/build.sh
./_scripts/install.sh
  and when you're done with it:
  ./_scripts/uninstall.sh

Have fun and make as many of your services highly available 🖖
Adrian Punga