PluginsCoreTask RunnersDocker

Docker​Docker

Docker Docker

yaml
type: "io.kestra.plugin.scripts.runner.docker.Docker"

Run a task in a Docker container.

This task runner executes tasks in a container-based Docker-compatible engine. Use the containerImage property to configure the image for the task.

To access the task's working directory, use the {{ workingDir }} Pebble expression or the WORKING_DIR environment variable. Input files and namespace files added to the task will be accessible from that directory.

To generate output files, we recommend using the outputFiles task's property. This allows you to explicitly define which files from the task's working directory should be saved as output files.

Alternatively, when writing files in your task, you can leverage the {{ outputDir }} Pebble expression or the OUTPUT_DIR environment variable. All files written to that directory will be saved as output files automatically.

Examples

Execute a Shell command.

yaml
id: simple_shell_example
namespace: company.team

tasks:
  - id: shell
    type: io.kestra.plugin.scripts.shell.Commands
    taskRunner:
      type: io.kestra.plugin.scripts.runner.docker.Docker
    commands:
    - echo "Hello World"

Pass input files to the task, execute a Shell command, then retrieve output files.

yaml
id: shell_example_with_files
namespace: company.team

inputs:
  - id: file
    type: FILE

tasks:
  - id: shell
    type: io.kestra.plugin.scripts.shell.Commands
    inputFiles:
      data.txt: "{{ inputs.file }}"
    outputFiles:
      - "*.txt"
    containerImage: centos
    taskRunner:
      type: io.kestra.plugin.scripts.runner.docker.Docker
    commands:
    - cp {{ workingDir }}/data.txt {{ workingDir }}/out.txt

Run a Python script in Docker and allocate a specific amount of memory.

yaml
id: allocate_memory_to_python_script
namespace: company.team

tasks:
  - id: script
    type: io.kestra.plugin.scripts.python.Script
    taskRunner:
      type: io.kestra.plugin.scripts.runner.docker.Docker
      pullPolicy: IF_NOT_PRESENT
      cpu:
        cpus: 1
      memory: 
        memory: "512Mb"
    containerImage: ghcr.io/kestra-io/kestrapy:latest
    script: |
      from kestra import Kestra
      
      data = dict(message="Hello from Kestra!"")
      Kestra.outputs(data)

Properties

delete

  • Type: boolean
  • Dynamic: ❌
  • Required: ✔️
  • Default: true

Whether the container should be deleted upon completion.

fileHandlingStrategy

  • Type: string
  • Dynamic: ❌
  • Required: ✔️
  • Default: VOLUME
  • Possible Values:
    • MOUNT
    • VOLUME

File handling strategy.

How to handle local files (input files, output files, namespace files, ...). By default, we create a volume and copy the file into the volume bind path. Configuring it to MOUNT will mount the working directory instead.

config

  • Type:
    • string
    • object
  • Dynamic: ✔️
  • Required: ❌

Docker configuration file.

Docker configuration file that can set access credentials to private container registries. Usually located in ~/.docker/config.json.

cpu

  • Type: Cpu
  • Dynamic: ❌
  • Required: ❌

Limits the CPU usage to a given maximum threshold value.

By default, each container’s access to the host machine’s CPU cycles is unlimited. You can set various constraints to limit a given container’s access to the host machine’s CPU cycles.

credentials

deviceRequests

A list of device requests to be sent to device drivers.

entryPoint

  • Type: array
  • SubType: string
  • Dynamic: ✔️
  • Required: ❌
  • Default: []

Docker entrypoint to use.

extraHosts

  • Type: array
  • SubType: string
  • Dynamic: ✔️
  • Required: ❌

Extra hostname mappings to the container network interface configuration.

host

  • Type: string
  • Dynamic: ✔️
  • Required: ❌

Docker API URI.

memory

  • Type: Memory
  • Dynamic: ❌
  • Required: ❌

Limits memory usage to a given maximum threshold value.

Docker can enforce hard memory limits, which allow the container to use no more than a given amount of user or system memory, or soft limits, which allow the container to use as much memory as it needs unless certain conditions are met, such as when the kernel detects low memory or contention on the host machine. Some of these options have different effects when used alone or when more than one option is set.

networkMode

  • Type: string
  • Dynamic: ✔️
  • Required: ❌

Docker network mode to use e.g. host, none, etc.

pullPolicy

  • Type: object
  • Dynamic: ❓
  • Required: ❌

shmSize

  • Type: string
  • Dynamic: ✔️
  • Required: ❌

Size of /dev/shm in bytes.

The size must be greater than 0. If omitted, the system uses 64MB.

user

  • Type: string
  • Dynamic: ✔️
  • Required: ❌

User in the Docker container.

volumes

  • Type: array
  • SubType: string
  • Dynamic: ✔️
  • Required: ❌

List of volumes to mount.

Make sure to provide a map of a local path to a container path in the format: /home/local/path:/app/container/path. Volume mounts are disabled by default for security reasons — if you are sure you want to use them, enable that feature in the plugin configuration by setting volume-enabled to true.

Here is how you can add that setting to your kestra configuration:

yaml
kestra:
  plugins:
    configurations:
      - type: io.kestra.plugin.scripts.runner.docker.Docker
        values:
          volume-enabled: true

Outputs

Definitions

io.kestra.plugin.scripts.runner.docker.Cpu

Properties

cpus
  • Type: integer
  • Dynamic: ❌
  • Required: ❌

The maximum amount of CPU resources a container can use.

Make sure to set that to a numeric value e.g. cpus: "1.5" or cpus: "4" or For instance, if the host machine has two CPUs and you set cpus: "1.5", the container is guaranteed at most one and a half of the CPUs.

io.kestra.plugin.scripts.runner.docker.Memory

Properties

kernelMemory
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The maximum amount of kernel memory the container can use.

The minimum allowed value is 4MB. Because kernel memory cannot be swapped out, a container which is starved of kernel memory may block host machine resources, which can have side effects on the host machine and on other containers. See the kernel-memory docs for more details.

memory
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The maximum amount of memory resources the container can use.

Make sure to use the format number + unit (regardless of the case) without any spaces. The unit can be KB (kilobytes), MB (megabytes), GB (gigabytes), etc.

Given that it's case-insensitive, the following values are equivalent:

  • "512MB"
  • "512Mb"
  • "512mb"
  • "512000KB"
  • "0.5GB"

It is recommended that you allocate at least 6MB.

memoryReservation
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

Allows you to specify a soft limit smaller than memory which is activated when Docker detects contention or low memory on the host machine.

If you use memoryReservation, it must be set lower than memory for it to take precedence. Because it is a soft limit, it does not guarantee that the container doesn’t exceed the limit.

memorySwap
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The total amount of memory and swap that can be used by a container.

If memory and memorySwap are set to the same value, this prevents containers from using any swap. This is because memorySwap includes both the physical memory and swap space, while memory is only the amount of physical memory that can be used.

memorySwappiness
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

A setting which controls the likelihood of the kernel to swap memory pages.

By default, the host kernel can swap out a percentage of anonymous pages used by a container. You can set memorySwappiness to a value between 0 and 100 to tune this percentage.

oomKillDisable
  • Type: boolean
  • Dynamic: ❌
  • Required: ❌

By default, if an out-of-memory (OOM) error occurs, the kernel kills processes in a container.

To change this behavior, use the oomKillDisable option. Only disable the OOM killer on containers where you have also set the memory option. If the memory flag is not set, the host can run out of memory, and the kernel may need to kill the host system’s processes to free the memory.

io.kestra.plugin.scripts.runner.docker.Credentials

Properties

auth
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The registry authentication.

The auth field is a base64-encoded authentication string of username:password or a token.

identityToken
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The identity token.

password
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The registry password.

registry
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The registry URL.

If not defined, the registry will be extracted from the image name.

registryToken
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The registry token.

username
  • Type: string
  • Dynamic: ✔️
  • Required: ❌

The registry username.

io.kestra.plugin.scripts.runner.docker.DeviceRequest

Properties

capabilities
  • Type: array
  • SubType: array
  • Dynamic: ❌
  • Required: ❌

A list of capabilities; an OR list of AND lists of capabilities.

count
  • Type: integer
  • Dynamic: ❌
  • Required: ❌
deviceIds
  • Type: array
  • SubType: string
  • Dynamic: ✔️
  • Required: ❌
driver
  • Type: string
  • Dynamic: ✔️
  • Required: ❌
options
  • Type: object
  • SubType: string
  • Dynamic: ❌
  • Required: ❌

Driver-specific options, specified as key/value pairs.

These options are passed directly to the driver.

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