Configure Local MinIO Storage for Kestra

Set up and verify a local MinIO storage backend for Kestra using the mc CLI and Docker.

This guide is intended for local development and testing only. MinIO is configured in gateway mode and exposed on localhost, without TLS or public access. Do not use this setup in production without additional security measures (e.g., HTTPS, access controls, and network isolation).

Install and Configure `mc` (MinIO Client)

Download and install the MinIO Client (mc) tool using the following command:

curl https://dl.min.io/client/mc/release/linux-amd64/mc --create-dirs -o $HOME/minio-binaries/mc && \
chmod +x $HOME/minio-binaries/mc && \
export PATH=$PATH:$HOME/minio-binaries/

Remove and Recreate Local Alias

Remove any existing local alias:

mc alias remove local

Recreate the alias with your MinIO access credentials:

mc alias set local http://localhost:9000 YOUR_ACCESS_KEY YOUR_SECRET_KEY

Create a Local Bucket

Create the bucket where outputs will be stored:

mc mb local/your_bucket

Start MinIO Server

Run the MinIO Docker container using the dedicated CI Compose file (e.g., from storage-minio):

docker compose -f docker-compose-ci.yml up

Configure Kestra for MinIO Storage

Update your application-psql.yml (or other relevant configuration file) under the kestra: section:

storage:
  type: minio
  minio:
    endpoint: localhost
    port: 9000
    bucket: your_bucket
    access-key: YOUR_ACCESS_KEY
    secret-key: YOUR_SECRET_KEY

Launch Kestra

Start Kestra as usual. Ensure the updated configuration file is correctly mounted or included.

Test with a Flow that Produces Outputs

Here is a sample flow that generates output files and logs intermediate data:

id: alligator_743987
namespace: company.team

tasks:
  - id: pass_output
    type: io.kestra.plugin.core.debug.Return
    format: hello

  - id: py_outputs
    type: io.kestra.plugin.scripts.python.Script
    taskRunner:
      type: io.kestra.plugin.scripts.runner.docker.Docker
      containerImage: ghcr.io/kestra-io/pydata:latest
    outputFiles:
      - myoutput.json
    script: |
      import json
      from kestra import Kestra
      my_kv_pair = {'mykey': 'from Kestra'}
      Kestra.outputs(my_kv_pair)
      with open('myoutput.json', 'w') as f:
          json.dump(my_kv_pair, f)

  - id: take_inputs
    type: io.kestra.plugin.core.log.Log
    message: |
      data from previous tasks: {{ outputs.pass_output.value }} and {{ outputs.py_outputs.vars.mykey }}

  - id: check_output_file
    type: io.kestra.plugin.scripts.shell.Commands
    taskRunner:
      type: io.kestra.plugin.core.runner.Process
    commands:
      - cat {{ outputs.py_outputs.outputFiles['myoutput.json'] }}

Verify Output in MinIO Bucket

You can now validate that the output file is stored in the MinIO bucket:

mc cat local/your_bucket/main/company/team/alligator-743987/executions/23z9cJWEa23kNAxu6sm0CT/tasks/py-outputs/5kxYRM7UqUurvnpVNvHca7/1noPFEiCFGPf2hcqjVzywu-myoutput.json

Note that you may need to replace the following placeholders with your own values:

the bucket name (here your_bucket)
the path (namespace) (here company/team)
the flow id (here alligator-743987)
the execution id (here 23z9cJWEa23kNAxu6sm0CT)
the task id (here py-outputs)
and finally the output file name (here 1noPFEiCFGPf2hcqjVzywu-myoutput.json)

The result should look like:

{"mykey": "from Kestra"}%

You have successfully configured and validated MinIO as a local storage backend for Kestra.