sqsjfr

sqsjfr

SQS job feeder.

sqsjfr reads a crontab (from local file, http URL, or S3 URL) and send job messages by the crontab schedules to Amazon SQS FIFO queue.

sqsjfr is designed to cooperate with sqsjkr, but runs as a standalone daemon to send messages to SQS.

Installation

binary packages

Releases.

Homebrew tap

$ brew install kayac/tap/sqsjfr

Usage

$ sqsjfr [options] (/path/to|http://...|s3://...)/crontab

Usage of sqsjfr:
  -check-interval duration
        interval of checking for crontab modified (default 1m0s)
  -dry-run
        dry run
  -log-level string
        log level (default "info")
  -message-template string
        SQS message template(JSON)
  -queue-url string
        SQS queue URL
  -stats-port int
        stats HTTP server port (default 8061)

Environment variables SQSJFR_* are also specify that options. For example, SQSJFR_QUEUE_URL=https://sqs.ap-northeast-1.amazonaws.com/123456789012/cron.fifo

Example

An example of crontab.

# comment
RUNNER=/usr/local/bin/job-runner

* * * * * echo "hello world! $(date)"; sleep 10; echo "goodby world! $(date)"
* * * * * $RUNNER -- date

A message template JSON.

{
  "command": "{{ .Command | json_escape }}",
  "invokedAt": "{{ .InvokedAt }}",
  "envs": {
    "HOME": "{{ must_env `HOME` }}",
    "RUNNER": "{{ .Env.RUNNER }}"
  }
}

Template syntax {{ }} will be expanded when SQS messages sent.

• .Command : A command line in crontab.
• .InvokedAt : Invocation UNIX time (truncated by a minute.).
• .Env : Environment variables map which defined in crontab. When a whole .Env is evaluated as a string, returns JSON string.
• must_env FOO : Environment variable "FOO" defined on a running sqsjfr process.

When -message-template is not specified, default SQS message generated as below.

{
  "command": "$RUNNER -- date",
  "invoked_at": 1602646620,
  "entry_id": 2,
  "envs": {
    "RUNNER":"/usr/local/bin/job-runner"
  }
}

$ sqsjfr \
    -queue-url https://sqs.ap-northeast-1.amazonaws.com/123456789012/cron.fifo \
    -message-template message.json \
    example.crontab
2020/10/13 23:03:21.087367 [info] starting up
2020/10/13 23:03:21.090266 [info] loading crontab example.crontab
2020/10/13 23:03:21.090720 [info] [entry:1] registered > * * * * * echo "hello world! $(date)"; sleep 10; echo "goodby world! $(date)"
2020/10/13 23:03:21.090742 [info] [entry:2] registered > * * * * * $RUNNER -- date
2020/10/13 23:03:21.090765 [info] defined > RUNNER=/usr/local/bin/job-runner
2020/10/13 23:03:21.090784 [info] 2 entries registered
2020/10/13 23:03:21.090791 [info] 1 environment variables defined
2020/10/13 23:03:21.090794 [info] running daemon
2020/10/13 23:04:01.085198 [info] [entry:1] invoke job {"command":"echo \"hello world! $(date)\"; sleep 10; echo \"goodby world! $(date)\"","envs":{"HOME":"/home/sqsjfr","RUNNER":"/usr/local/bin/job-runner"},"invokedAt":"1602597840"}
2020/10/13 23:04:01.849199 [info] [entry:2] invoke job {"command":"$RUNNER -- date","envs":{"HOME":"/home/sqsjfr","RUNNER":"/usr/local/bin/job-runner"},"invokedAt":"1602597840"}

Schedule specs are parsed by github.com/robfig.

• Blank lines and leading spaces and tabs are ignored.
• Lines whose first non-space character is a pound-sign (#) are comments, and are ignored.

Stats HTTP server

sqsjfr runs a stats HTTP server on port -stats-port(defalt 8061).

The endpoint returns metrics as JSON format.

{
  "entries": {
    "registered": 2
  },
  "invocations": {
    "succeeded": 12,
    "failed": 0
  }
}

High Availability

sqsjfr can be deployed by multi processes for high availability deployment.

sqsjfr sends SQS messages with MessageDeduplicationId option for SQS FIFO queue. MessageDeduplicationId is generated by a message body and an invoked UNIX timestamp(truncated by a minute).

Therefore even if multi sqsjfr processes send the same messages(has the same body and timestamp) at the same time, FIFO queue delivers one message to consumers.

LICENSE

MIT