Run jobs (tasks/one-shot containers) on Docker Swarm
This project provides a simple Golang CLI tool that binds to the Docker Swarm API to create an ad-hoc/one-shot Service and then poll until it exits. Service logs can also be retrieved if the Docker daemon API version is greater than 1.29 or if the experimental feature is enabled on the Docker daemon.
For a blog post covering use-cases for JaaS and more on the portions of the Docker API used see below:
Use-cases:
- Use an elastic cluster as your computer
- Clean up DB indexes
- Send emails
- Batch processing
- Replace cron scripts
- Run your server maintenance tasks
- Schedule dev-ops tasks
If you would like to build Serverless applications with Kubernetes or Docker Swarm checkout OpenFaaS:
The OpenFaaS project has dozens of contributors and thousands of GitHub stars - if you're here because you want to run short-lived functions then I highly recommend checking out OpenFaaS now.
Pre-requisites:
- Docker 1.13 or newer (experimental mode must be enabled if accessing service logs with Docker versions >= 1.13 and < 1.29)
- Go 1.9.2 (or Golang container)
- Enable Swarm Mode (
docker swarm init)
Run these commands
# export GOPATH=$HOME/go
# go get -d -v github.com/alexellis/jaas
# cd $GOPATH/src/github.com/alexellis/jaas
# go install
# export PATH=$PATH:$GOPATH/bin
Now test jaas with jaas --help
- Run your first one-shot container with
jaas run:
# jaas run -r --image alexellis2/cows:latest
The -r flag removes the Swarm service that was used to run your container.
The exit code from your container will also be available, you can check it with
echo $?
- Hiding logs
If you aren't interested in the output logs then run it with the --show-logs=false override:
# jaas run --image alexellis2/cows:latest --show-logs=false
- Override the command of the container
# jaas run --image alpine:3.8 --command "uname -a"
Printing service logs
w2018-02-06T13:40:00.131678932Z Linux f56d298c4ab9 4.9.75-linuxkit-aufs #1 SMP Tue Jan 9 10:58:17 UTC 2018 x86_64 Linux
- Environment variables
Set environment variables with --env or -e:
# jaas run --image alpine:3.8 --env ENV1=val1 --env ENV2=val2 --command "env"
Service created: inspiring_elion (j90qjtc14usgps9t60tvogmts)
ID: j90qjtc14usgps9t60tvogmts Update at: 2018-07-14 18:02:57.147797437 +0000 UTC
...........
Exit code: 0
State: complete
Printing service logs
a2018-07-14T18:03:01.465983797Z PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
52018-07-14T18:03:01.466098037Z HOSTNAME=de0b5614fc88
)2018-07-14T18:03:01.466111965Z ENV1=val1
)2018-07-14T18:03:01.466122558Z ENV2=val2
*2018-07-14T18:03:01.466132520Z HOME=/root
Removing service...
- Removing service after completion
By default, the service is removed after it completes. To prevent that, run with the --remove or -r flag set to false:
# jaas run --image alpine:3.8 --remove=false
Service created: zen_hoover (nwf2zey3i387zkx5gp7yjk053)
ID: nwf2zey3i387zkx5gp7yjk053 Update at: 2018-07-08 20:19:39.320494122 +0000 UTC
............
Exit code: 0
State: complete
Printing service logs
# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
nwf2zey3i387 zen_hoover replicated 0/1 alpine:3.7
- Docker authentication for registries
You can use jaas with Docker images in private registries or registries which require authentication.
Just run docker login then pass the --registry parameter and the encoded string you find in ~/.docker/config.json.
If you want to encode a string manually then do the following:
$ export auth='{
"username" : "myUserName",
"password" : "secret",
"email" : "my@email",
"serveraddress" : "my.reg.domain"
}'
$ jaas run --registry="`echo $auth | base64`" --image my.reg.domain/hello-world:latest- Adding secret to service
To give the service access to an existing secret. run with the --secret or -s flag:
$ echo -n "S3_ACCESS_KEY_HERE" | docker secret create s3-access-key -
$ jaas run --image alpine:3.7 --secret s3-access-key --command "cat /run/secrets/s3-access-key"
Service created: priceless_tesla (f8gheat9f3b8cnnsjy9dth9y7)
ID: f8gheat9f3b8cnnsjy9dth9y7 Update at: 2018-06-29 16:41:13.723257461 +0000 UTC
...........
Exit code: 0
State: complete
Printing service logs
(2018-06-29T16:41:19.057738088Z S3_ACCESS_KEY_HERE
Removing service...
Notes on images
You can have a multi-node swarm but make sure whatever image you choose is available in an accessible registry.
A local image will not need to be pushed to a registry.
- Running jaas in a container
You can also run jaas in a container, but the syntax becomes slightly more verbose:
# docker run -ti -v /var/run/docker.sock:/var/run/docker.sock \
alexellis2/jaas run --image alexellis2/cows:latest
You can use jaas to get the value of your OpenFaaS gateway password on Docker Swarm. See the OpenFaaS troubleshooting guide for the usage.
Here are several features / enhancements on the roadmap, please make additional suggestions through Github issues.
- Optionally delete service after fetching exit code/logs
- Support passing environmental variables
- Support private registry auth via
-registryAuthflag - Move to cobra flags/args package for CLI
- Support constraints on where to run tasks
- Bind-mounting volumes
- Overriding container command
- Support optional secrets through CLI flag
Todo:
- Validation around images which are not in local library
- Extract stdout/stderr etc from logs in human readable format similar to
docker logs
- When task logs are available in the API this will be used instead of service logs.
- When event streams are released they will prevent the need to poll continually
See the contributing guide and do not raise a PR unless you've read it all.