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Configuring Your Artifact Repository

To run Argo workflows that use artifacts, you must configure and use an artifact repository. Argo supports any S3 compatible artifact repository such as AWS, GCS and Minio. This section shows how to configure the artifact repository. Subsequent sections will show how to use it.

Name Inputs Outputs Usage (Feb 2020)
Artifactory Yes Yes 11%
GCS Yes Yes -
Git Yes No -
HDFS Yes Yes 3%
HTTP Yes No 2%
OSS Yes Yes -
Raw Yes No 5%
S3 Yes Yes 86%

The actual repository used by a workflow is choosen by the following rules:

  1. Anything explicitly configured using Artifact Repository Ref. This is the most flexible, safe, and secure option.
  2. From a config map named artifact-repositories if it has the workflows.argoproj.io/default-artifact-repository annotation in the workflow's namespace.
  3. From a workflow controller configmap.

Configuring Minio

$ brew install helm # mac, helm 3.x
$ helm repo add minio https://helm.min.io/ # official minio Helm charts
$ helm repo update
$ helm install argo-artifacts minio/minio --set service.type=LoadBalancer --set fullnameOverride=argo-artifacts

Login to the Minio UI using a web browser (port 9000) after obtaining the external IP using kubectl.

$ kubectl get service argo-artifacts

On Minikube:

$ minikube service --url argo-artifacts

NOTE: When minio is installed via Helm, it generates credentials, which you will use to login to the UI: Use the commands shown below to see the credentials

  • AccessKey: kubectl get secret argo-artifacts -o jsonpath='{.data.accesskey}' | base64 --decode
  • SecretKey: kubectl get secret argo-artifacts -o jsonpath='{.data.secretkey}' | base64 --decode

Create a bucket named my-bucket from the Minio UI.

Configuring AWS S3

Create your bucket and access keys for the bucket. AWS access keys have the same permissions as the user they are associated with. In particular, you cannot create access keys with reduced scope. If you want to limit the permissions for an access key, you will need to create a user with just the permissions you want to associate with the access key. Otherwise, you can just create an access key using your existing user account.

$ export mybucket=bucket249
$ cat > policy.json <<EOF
{
   "Version":"2012-10-17",
   "Statement":[
      {
         "Effect":"Allow",
         "Action":[
            "s3:PutObject",
            "s3:GetObject"
         ],
         "Resource":"arn:aws:s3:::$mybucket/*"
      }
   ]
}
EOF
$ aws s3 mb s3://$mybucket [--region xxx]
$ aws iam create-user --user-name $mybucket-user
$ aws iam put-user-policy --user-name $mybucket-user --policy-name $mybucket-policy --policy-document file://policy.json
$ aws iam create-access-key --user-name $mybucket-user > access-key.json

NOTE: if you want argo to figure out which region your buckets belong in, you must additionally set the following statement policy. Otherwise, you must specify a bucket region in your workflow configuration.

    ...
      {
         "Effect":"Allow",
         "Action":[
            "s3:GetBucketLocation"
         ],
         "Resource":"arn:aws:s3:::*"
      }
    ...

Configuring GCS (Google Cloud Storage)

Create a bucket from the GCP Console (https://console.cloud.google.com/storage/browser).

There are 2 ways to configure a Google Cloud Storage.

Through Native GCS APIs

  • Create and download a Google Cloud service account key.
  • Create a kubernetes secret to store the key.
  • Configure gcs artifact as following in the yaml.
artifacts:
  - name: message
    path: /tmp/message
    gcs:
      bucket: my-bucket-name
      key: path/in/bucket
      # serviceAccountKeySecret is a secret selector.
      # It references the k8s secret named 'my-gcs-credentials'.
      # This secret is expected to have have the key 'serviceAccountKey',
      # containing the base64 encoded credentials
      # to the bucket.
      #
      # If it's running on GKE and Workload Identity is used,
      # serviceAccountKeySecret is not needed.
      serviceAccountKeySecret:
        name: my-gcs-credentials
        key: serviceAccountKey

If it's a GKE cluster, and Workload Identity is configured, there's no need to create the Service Account key and store it as a K8s secret, serviceAccountKeySecret is also not needed in this case. Please follow the link to configure Workload Identity (https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity).

Use S3 APIs

Enable S3 compatible access and create an access key. Note that S3 compatible access is on a per project rather than per bucket basis.

  • Navigate to Storage > Settings (https://console.cloud.google.com/storage/settings).
  • Enable interoperability access if needed.
  • Create a new key if needed.
  • Configure s3 artifact as following example.
artifacts:
  - name: my-output-artifact
    path: /my-output-artifact
    s3:
      endpoint: storage.googleapis.com
      bucket: my-gcs-bucket-name
      # NOTE that, by default, all output artifacts are automatically tarred and
      # gzipped before saving. So as a best practice, .tgz or .tar.gz
      # should be incorporated into the key name so the resulting file
      # has an accurate file extension.
      key: path/in/bucket/my-output-artifact.tgz
      accessKeySecret:
        name: my-gcs-s3-credentials
        key: accessKey
      secretKeySecret:
        name: my-gcs-s3-credentials
        key: secretKey

Configuring Alibaba Cloud OSS (Object Storage Service)

To configure artifact storage for Alibaba Cloud OSS, please first follow the official documentation to set up an OSS account and bucket.

Once it's set up, you can find endpoint and bucket information on your OSS dashboard and then use them like the following to configure the artifact storage for your workflow:

artifacts:
  - name: my-art
    path: /my-artifact
    oss:
      endpoint: http://oss-cn-hangzhou-zmf.aliyuncs.com
      bucket: test-bucket-name
      key: test/mydirectory/ # this is path in the bucket
      # accessKeySecret and secretKeySecret are secret selectors.
      # It references the k8s secret named 'my-oss-credentials'.
      # This secret is expected to have have the keys 'accessKey'
      # and 'secretKey', containing the base64 encoded credentials
      # to the bucket.
      accessKeySecret:
        name: my-oss-credentials
        key: accessKey
      secretKeySecret:
        name: my-oss-credentials
        key: secretKey

You can also set createBucketIfNotPresent to true to tell the artifact driver to automatically create the OSS bucket if it doesn't exist yet when saving artifacts. Note that you'll need to set additional permission for your OSS account to create new buckets.

Configure the Default Artifact Repository

In order for Argo to use your artifact repository, you can configure it as the default repository. Edit the workflow-controller config map with the correct endpoint and access/secret keys for your repository.

S3 compatible artifact repository bucket (such as AWS, GCS, Minio, and Alibaba Cloud OSS)

Use the endpoint corresponding to your provider:

  • AWS: s3.amazonaws.com
  • GCS: storage.googleapis.com
  • Minio: my-minio-endpoint.default:9000
  • Alibaba Cloud OSS: oss-cn-hangzhou-zmf.aliyuncs.com

The key is name of the object in the bucket The accessKeySecret and secretKeySecret are secret selectors that reference the specified kubernetes secret. The secret is expected to have the keys 'accessKey' and 'secretKey', containing the base64 encoded credentials to the bucket.

For AWS, the accessKeySecret and secretKeySecret correspond to AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY respectively.

EC2 provides a metadata API via which applications using the AWS SDK may assume IAM roles associated with the instance. If you are running argo on EC2 and the instance role allows access to your S3 bucket, you can configure the workflow step pods to assume the role. To do so, simply omit the accessKeySecret and secretKeySecret fields.

For GCS, the accessKeySecret and secretKeySecret for S3 compatible access can be obtained from the GCP Console. Note that S3 compatible access is on a per project rather than per bucket basis.

  • Navigate to Storage > Settings (https://console.cloud.google.com/storage/settings).
  • Enable interoperability access if needed.
  • Create a new key if needed.

For Minio, the accessKeySecret and secretKeySecret naturally correspond the AccessKey and SecretKey.

For Alibaba Cloud OSS, the accessKeySecret and secretKeySecret corresponds to accessKeyID and accessKeySecret respectively.

Example:

$ kubectl edit configmap workflow-controller-configmap -n argo      # assumes argo was installed in the argo namespace
...
data:
  artifactRepository: |
    s3:
      bucket: my-bucket
      keyFormat: prefix/in/bucket     #optional
      endpoint: my-minio-endpoint.default:9000        #AWS => s3.amazonaws.com; GCS => storage.googleapis.com
      insecure: true                  #omit for S3/GCS. Needed when minio runs without TLS
      accessKeySecret:                #omit if accessing via AWS IAM
        name: my-minio-cred
        key: accessKey
      secretKeySecret:                #omit if accessing via AWS IAM
        name: my-minio-cred
        key: secretKey
      useSDKCreds: true               #tells argo to use AWS SDK's default provider chain, enable for things like IRSA support

The secrets are retrieved from the namespace you use to run your workflows. Note that you can specify a keyFormat.

Google Cloud Storage (GCS)

Argo also can use native GCS APIs to access a Google Cloud Storage bucket.

serviceAccountKeySecret references to a k8 secret which stores a Google Cloud service account key to access the bucket.

Example:

$ kubectl edit configmap workflow-controller-configmap -n argo  # assumes argo was installed in the argo namespace
...
data:
  artifactRepository: |
    gcs:
      bucket: my-bucket
      keyFormat: prefix/in/bucket     #optional, it could reference workflow variables, such as "{{workflow.name}}/{{pod.name}}"
      serviceAccountKeySecret:
        name: my-gcs-credentials
        key: serviceAccountKey

Accessing Non-Default Artifact Repositories

This section shows how to access artifacts from non-default artifact repositories.

The endpoint, accessKeySecret and secretKeySecret are the same as for configuring the default artifact repository described previously.

  templates:
  - name: artifact-example
    inputs:
      artifacts:
      - name: my-input-artifact
        path: /my-input-artifact
        s3:
          endpoint: s3.amazonaws.com
          bucket: my-aws-bucket-name
          key: path/in/bucket/my-input-artifact.tgz
          accessKeySecret:
            name: my-aws-s3-credentials
            key: accessKey
          secretKeySecret:
            name: my-aws-s3-credentials
            key: secretKey
    outputs:
      artifacts:
      - name: my-output-artifact
        path: /my-output-artifact
        s3:
          endpoint: storage.googleapis.com
          bucket: my-gcs-bucket-name
          # NOTE that, by default, all output artifacts are automatically tarred and
          # gzipped before saving. So as a best practice, .tgz or .tar.gz
          # should be incorporated into the key name so the resulting file
          # has an accurate file extension.
          key: path/in/bucket/my-output-artifact.tgz
          accessKeySecret:
            name: my-gcs-s3-credentials
            key: accessKey
          secretKeySecret:
            name: my-gcs-s3-credentials
            key: secretKey
          region: my-GCS-storage-bucket-region
    container:
      image: debian:latest
      command: [sh, -c]
      args: ["cp -r /my-input-artifact /my-output-artifact"]