A CLI tool for running any shell based commands in a distributed environment with DynamoDB locking.

Requirements

• Go 1.14+
• DynamoDB Table
  • Ensure partition key is name key. An upstream requirement from dynamolock/

Getting Started

 go get -u loomhq/lock-exec

Defaults

• DynamoDB table name: lock-exec
• AWS Region: us-west-2

Examples

A CLI tool for running any shell based commands in a distributed environment with DynamoDB locking

Usage:
  lock-exec [command]

Available Commands:
  help        Help about any command
  run         Run a shell command with acquire lock
  unlock      Force release an already acquired lock using key name

Flags:
  -h, --help            help for lock-exec
  -k, --key string      Name of the key (required)
  -r, --region string   AWS Region Name (default: "us-west-2")
  -t, --table string    Table Name (default: "lock-exec")

Use "lock-exec [command] --help" for more information about a command.

Key name and command

lock-exec run -k job-runner-foo -c "/usr/local/bin/do-something"

Key name, region, table command

lock-exec run-k job-runner-foo -r "us-west-2" -t "lock-exec" -c "/usr/local/bin/do-something"

Overhead

• CPU: <1%
• Mem/RSS: ~30MB

Tested on local MacOS machine.

Required DynamoDB Actions

The following IAM permissions are required on the DynamoDB table containing the locks:

• GetItem
• PutItem
• UpdateItem
• DeleteItem

Random sleep and jitter like behavior

For use cases where the locking client is not atomic/fast enough, you can include a randomized sleep (with upper bound) to have jitter like behavior and stagger other execution when the task begins. Similarly, you can hold the lock after task completion to avoid other executions from acquiring the lock again. Examples

Usage:
  lock-exec run [flags]

Flags:
  -c, --command string           Shell Command (required)
  -h, --help                     help for run
  -l, --hold-lock int            Adds a sleep after running the command and before releasing the lock.
  -s, --sleep-start-random int   Adds a randomized sleep before running the command to add jitter like effect. Value in seconds and is the upper bound for the randomized sleep duration.

Global Flags:
  -k, --key string      Name of the key (required)
  -r, --region string   AWS Region Name (default: "us-west-2") (default "us-west-2")
  -t, --table string    Table Name (default: "lock-exec") (default "lock-exec")

Randomized sleep

lock-exec run-k job-runner-foo -r "us-west-2" -t "lock-exec" -c "/usr/local/bin/do-something" -s 10 // seconds

Holding lock post completion

lock-exec run-k job-runner-foo -r "us-west-2" -t "lock-exec" -c "/usr/local/bin/do-something" -l 60 // seconds

Development & Release

Requirements

Install goreleaser

brew install goreleaser/tap/goreleaser

Publishing new release

Publishing of package is managed by goreleaser.

# Tag
git tag -a v0.1.0 -m 'v0.1.0'
git push origin v0.1.0

# release - from the root of your repository
export GITHUB_TOKEN=<>
goreleaser release