lockd

A distributed lock service.

Development

Run using:

go mod download
go run main.go -cluster integtests/config/1node.json -id 1

In another terminal, run the following:

curl -i -X POST http://localhost:2081/lock/foo

Multi-Node Cluster

To run a multi-node cluster in development, run the following in separate terminals:

# 1st terminal
go build && ./lockd -cluster integtests/config/3nodes.json -id 101

# 2nd terminal
./lockd -cluster integtests/config/3nodes.json -id 102

# 3rd terminal
./lockd -cluster integtests/config/3nodes.json -id 103

# 4th terminal
go run integtests/main.go

Lock API

The lock service has a REST-ful interface: every lock is a resource at the path /lock/:name:

GET /lock/:name

Check if the given entry is locked.

This will return one of the following status codes:

• 200 OK - Entry is locked.
• 404 Not Found - Entry is unlocked.
• 503 Service Unavailable - Node is not the leader of the cluster.

Example:

curl -i http://localhost:2081/lock/foo

POST /lock/:name

Lock the given entry.

This will return one of the following status codes:

• 200 OK - Success - entry is now locked.
• 409 Conflict - Failed - entry is locked.
• 503 Service Unavailable - Node is not the leader of the cluster.

Example:

curl -i -X POST http://localhost:2081/lock/foo

DELETE /lock/:name

Unlock the given entry.

This will return one of the following status codes:

• 200 OK - Success - entry is now locked.
• 409 Conflict - Failed - entry is locked.
• 503 Service Unavailable - Node is not the leader of the cluster.

Example:

curl -i -X DELETE http://localhost:2081/lock/foo

TODO

Basic Daemon:

• command line param: server listen address
• logging setup
• gin logging to golang standard logging bridge

Basic Single-Node Locking:

• Lock & Unlock API endpoints
• Lock state persistence API
• In-memory state persistence
• Implement single-node locking service
• Refactor to use raft as single-node cluster
• Lock wait for raft commit

Lock Features:

• Lock status query API
• Lock request/client id field
• Request/client id override
• Lock acquire wait time

Error Handling:

• Internal error shows original stack trace
• API timeouts
• Field content and size limit checks
• Avoid/delay panic where possible

Integration Testing:

• External test script
• Travis runs server and test script

Lock State Persistence:

• Boltdb state persistence
• Command line param: choice of persistence mode
• Command line param: Boltdb state file name

Lock TTL:

• Lock TTL params
• Expired Lock Unlocker

Lock Admin:

• List Locks API
• Web UI: basic assets
• Web UI: list locks
• Web UI: lock
• Web UI: unlock

Multi-Node Locking:

• raft consensus module
• cluster support
• listen port using cluster info
• raft rpc endpoints
• peer rpc service
• change default port back to 2080
• default port when port not specified
• easy single node option
• clients support for cluster
• proxy Lock & Unlock API calls to raft leader
• raft snapshotting

Clients:

• Ruby client
• Python client
• Java/Scala client

Servers:

• Homebrew installable binary
• Linux binary

Misc:

• Add metrics & logging
• Expose raft details e.g. leader, term
• Stop -help from showing "-httptest.serve"
• Vendorize dependencies