Elastic Whenever
Manage ECS scheduled tasks like Whenever gem.
Installation
Add this line to your application's Gemfile:
gem 'elastic_whenever'
And then execute:
$ bundle
Or install it yourself as:
$ gem install elastic_whenever
Usage
You can use it almost like Whenever. However, please be aware that you must specify an identifier.
$ elastic_whenever --help
Usage: elastic_whenever [options]
-i, --update identifier Clear and create scheduled tasks by schedule file
-c, --clear identifier Clear scheduled tasks
-l, --list identifier List scheduled tasks
-s, --set variables Example: --set 'environment=staging'
--cluster cluster ECS cluster to run tasks
--task-definition task_definition
Task definition name, If omit a revision, use the latest revision of the family automatically. Example: --task-deifinition oneoff-application:2
--container container Container name defined in the task definition
--launch-type launch_type Launch type. EC2 or FARGATE. Defualt: EC2
--assign-public-ip Assign a public IP. Default: DISABLED (FARGATE only)
--security-groups groups Example: --security-groups 'sg-2c503655,sg-72f0cb0a' (FARGATE only)
--subnets subnets Example: --subnets 'subnet-4973d63f,subnet-45827d1d' (FARGATE only)
--platform-version version Optionally specify the platform version. Default: LATEST (FARGATE only)
-f, --file schedule_file Default: config/schedule.rb
--iam-role name IAM role name used by CloudWatch Events. Default: ecsEventsRole
--profile profile_name AWS shared profile name
--access-key aws_access_key_id
AWS access key ID
--secret-key aws_secret_access_key
AWS secret access key
--region region AWS region
-v, --version Print version
-V, --verbose Run rake jobs without --silent
NOTE: Currently, Elastic Whenever supports the Whenever syntax partially. We strongly encourage to use dry-run mode for verifying tasks to be created.
$ elastic_whenever --cluster ecs-test --task-definition example:2 --container cron
cron(0 3 * * ? *) ecs-test example:2 cron bundle exec rake hoge:run
## [message] Above is your schedule file converted to scheduled tasks; your scheduled tasks was not updated.
## [message] Run `elastic_whenever --help' for more options.
How it works
Elastic Whenever creates CloudWatch Events as many as every
block. Each event has as many targets as there are commands in the block.
every '0 0 * * *' do # scheduled task (identifier_68237a3b152a6c44359e1cf5cd8e7cf0def303d7)
rake "hoge:run" # target for `identifier_68237a3b152a6c44359e1cf5cd8e7cf0def303d7`
command "awesome" # target for `identifier_68237a3b152a6c44359e1cf5cd8e7cf0def303d7`
end
The scheduled task's name is a digest value calculated from an identifier, commands, and so on.
NOTE: You should not use the same identifier across different clusters because CloudWatch Events rule names are unique across all clusters.
Compatible with Whenever
job_type
Whenever supports custom job type with job_type
method, but Elastic Whenever doesn't support it.
# [warn] Skipping unsupported method: job_type
job_type :awesome, '/usr/local/bin/awesome :task :fun_level'
env
Whenever supports environment variables with env
method, but Elastic Whenever doesn't support it.
You should use task definitions to set environment variables.
# [warn] Skipping unsupported method: env
env "VERSION", "v1"
:job_template
Whenever has a template to describe as cron, but Elastic Whenever doesn't have the template.
Therefore, :job_template
option is ignored.
set :job_template, "/bin/zsh -l -c ':job'" # ignored
Frequency
Elastic Whenever processes frequency passed to every
block almost like Whenever.
# Whenever
# 0 15 * * * /bin/bash -l -c 'cd /home/user/app && RAILS_ENV=production bundle exec rake hoge:run --silent'
#
# Elastic Whenever
# cron(0 15 * * ? *) ecs-test myapp:2 web bundle exec rake hoge:run --silent
#
every :day, at: "3:00" do
rake "hoge:run"
end
# Whenever
# 0,10,20,30,40,50 * * * * /bin/bash -l -c 'awesome'
#
# Elastic Whenever
# cron(0,10,20,30,40,50 * * * ? *) ecs-test myapp:2 web awesome
#
every 10.minutes do
command "awesome"
end
However, handling of the day of week is partially different because it follows scheduled expression.
# Whenever
# 0 0 * * 1 /bin/bash -l -c 'awesome'
#
# Elastic Whenever
# cron(0 0 ? * 2 *) ecs-test myapp:2 web awesome
#
every :monday do
command "awesome"
end
Therefore, cron syntax is converted to scheduled expression like the following:
# cron(0 0 ? * 2 *) ecs-test myapp:2 web awesome
every "0 0 * * 1" do
command "awesome"
end
Absolutely, you can also write scheduled expression.
# cron(0 0 ? * 2 *) ecs-test myapp:2 web awesome
every "0 0 ? * 2 *" do
command "awesome"
end
:reboot
Whenever supports :reboot
as a cron option, but Elastic Whenever doesn't support it.
# [warn] `reboot` is not supported option. Ignore this task.
every :reboot do
rake "hoge:run"
end
Bundle commands
Whenever checks if the application uses bundler and automatically adds a prefix to commands. However, Elastic Whenever always adds a prefix on a premise that the application is using bundler.
# Whenever
# With bundler -> bundle exec rake hoge:run
# Without bundler -> rake hoge:run
#
# Elastic Whenever
# bundle exec rake hoge:run
#
rake "hoge:run"
If you don't want to add the prefix, set bundle_command
to empty as follows:
set :bundle_command, ""
Rails
Whenever supports runner
job with old Rails versions, but Elastic Whenever supports Rails 4 and above only.
# Whenever
# Before them -> script/runner Hoge.run
# Rails 3 -> script/rails runner Hoge.run
# Rails 4 -> bin/rails runner Hoge.run
#
# Elastic Whenever
# bin/rails runner Hoge.run
#
runner "Hoge.run"
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run rake spec
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/wata727/elastic_whenever.