docker-crontab

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A docker job scheduler (aka. crontab for docker)

// repository documentation

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# docker-crontab

A simple wrapper over `docker` to all complex cron job to be run in other containers.

## Supported tags and Dockerfile links

-	[`latest` (*Dockerfile*)](https://github.com/willfarrell/docker-crontab/blob/master/Dockerfile)
-	[`1.0.0` (*Dockerfile*)](https://github.com/willfarrell/docker-crontab/blob/1.0.0/Dockerfile)
-	[`0.6.0` (*Dockerfile*)](https://github.com/willfarrell/docker-crontab/blob/0.6.0/Dockerfile)

![](https://img.shields.io/docker/pulls/willfarrell/crontab "Total docker pulls") [![](https://images.microbadger.com/badges/image/willfarrell/crontab.svg)](http://microbadger.com/images/willfarrell/crontab "Get your own image badge on microbadger.com")

## Why?
Yes, I'm aware of [mcuadros/ofelia](https://github.com/mcuadros/ofelia) (>250MB when this was created), it was the main inspiration for this project. 
A great project, don't get me wrong. It was just missing certain key enterprise features I felt were required to support where docker is heading.

## Features
- Easy to read schedule syntax allowed.
- Allows for comments, cause we all need friendly reminders of what `update_script.sh` actually does.
- Start an image using `image`.
- Run command in a container using `container`.
- Run command on a instances of a scaled container using `project`.
- Ability to trigger scripts in other containers on completion cron job using `trigger`.

## Config file

The config file can be specifed in any of `json`, `toml`, or `yaml`, and can be defined as either an array or mapping (top-level keys will be ignored; can be useful for organizing commands)

- `name`: Human readable name that will be used as the job filename. Will be converted into a slug. Optional.
- `comment`: Comments to be included with crontab entry. Optional.
- `schedule`: Crontab schedule syntax as described in https://en.wikipedia.org/wiki/Cron. Ex `@hourly`, `@every 1h30m`, `* * * * *`. Required.
- `command`: Command to be run on in crontab container or docker container/image. Required.
- `image`: Docker images name (ex `library/alpine:3.5`). Optional.
- `project`: Docker Compose/Swarm project name. Optional, only applies when `contain` is included.
- `container`: Full container name or container alias if `project` is set. Ignored if `image` is included. Optional.
- `dockerargs`: Command line docker `run`/`exec` arguments for full control. Defaults to ` `.
- `trigger`: Array of docker-crontab subset objects. Subset includes: `image`,`project`,`container`,`command`,`dockerargs` 
- `onstart`: Run the command on `crontab` container start, set to `true`. Optional, defaults to falsey.

See [`config-samples`](config-samples) for examples.

```json
[{
 	"schedule":"@every 5m",
 	"command":"/usr/sbin/logrotate /etc/logrotate.conf"
 },{
 	"comment":"Regenerate Certificate then reload nginx",
 	"schedule":"43 6,18 * * *",
 	"command":"sh -c 'dehydrated --cron --out /etc/ssl --domain ${LE_DOMAIN} --challenge dns-01 --hook dehydrated-dns'",
 	"dockerargs":"--env-file /opt/crontab/env/letsencrypt.env -v webapp_nginx_tls_cert:/etc/ssl -v webapp_nginx_acme_challenge:/var/www/.well-known/acme-challenge",
 	"image":"willfarrell/letsencrypt",
 	"trigger":[{
 		"command":"sh -c '/etc/scripts/make_hpkp ${NGINX_DOMAIN} && /usr/sbin/nginx -t && /usr/sbin/nginx -s reload'",
 		"project":"conduit",
 		"container":"nginx"
 	}],
 	"onstart":true
 }]
```

## How to use

### Command Line

```bash
docker build -t crontab .
docker run -d \
    -v /var/run/docker.sock:/var/run/docker.sock:ro \
    -v ./env:/opt/env:ro \
    -v /path/to/config/dir:/opt/crontab:rw \
    -v /path/to/logs:/var/log/crontab:rw \
    crontab
```

### Use with docker-compose

1. Figure out which network name used for your docker-compose containers
	* use `docker network ls` to see existing networks
	* if your `docker-compose.yml` is in `my_dir` directory, you probably has network `my_dir_default`
	* otherwise [read the docker-compose docs](https://docs.docker.com/compose/networking/)
2. Add `dockerargs` to your docker-crontab `config.json`
	* use `--network NETWORK_NAME` to connect new container into docker-compose network
	* use `--rm --name NAME` to use named container
	* e.g. `"dockerargs": "--network my_dir_default --rm --name my-best-cron-job"`

### Dockerfile

```Dockerfile
FROM willfarrell/crontab

COPY config.json ${HOME_DIR}/

```

### Logrotate Dockerfile

```Dockerfile
FROM willfarrell/crontab

RUN apk add --no-cache logrotate
RUN echo "*/5 *	* * *  /usr/sbin/logrotate /etc/logrotate.conf" >> /etc/crontabs/logrotate
COPY logrotate.conf /etc/logrotate.conf

CMD ["crond", "-f"]
```

### Logging - In Dev

All `stdout` is captured, formatted, and saved to `/var/log/crontab/jobs.log`. Set `LOG_FILE` to `/dev/null` to disable logging.

example: `e6ced859-1563-493b-b1b1-5a190b29e938 2017-06-18T01:27:10+0000 [info] Start Cronjob **map-a-vol** map a volume`

grok: `CRONTABLOG %{DATA:request_id} %{TIMESTAMP_ISO8601:timestamp} \[%{LOGLEVEL:severity}\] %{GREEDYDATA:message}`

## TODO
- [ ] Have ability to auto regenerate crontab on file change (signal HUP?)
- [ ] Run commands on host machine (w/ --privileged?)
- [ ] Write tests
- [ ] Setup TravisCI

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