When using Argo daemon containers, referencing the IP of a previous step is well-supported via the {{steps.<step-name>.ip}} variable:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: sidecar-nginx-
spec:
  entrypoint: sidecar-nginx-example
  templates:
  - name: sidecar-nginx-example
    steps:
      - - name: start-nginx
          template: nginx-daemon
      - - name: curl-nginx
          template: curl-container
          arguments:
            parameters:
              - name: nginx-ip
                value: "{{steps.start-nginx.ip}}"

  - name: nginx-daemon
    daemon: true
    retryStrategy:
      limit: 3
    container:
      name: nginx
      image: nginx:1.13
      command: [nginx, -g, "daemon off;"]
    nodeSelector:
      kubernetes.io/os: linux

  - name: curl-container
    inputs:
      parameters:
        - name: nginx-ip
    container:
      image: appropriate/curl
      command: [sh, -c]
      args: ["until `curl -G 'http://{{inputs.parameters.nginx-ip}}/' >& /tmp/out`; do echo sleep && sleep 1; done && cat /tmp/out"]
    nodeSelector:
      kubernetes.io/os: linux

However, when using non-daemon containers, the convenient {{steps.<step-name>.ip}} variable is not available. So I’m looking for a good way to access pod metadata (IP or name) in later workflow steps.

Here is one approach:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: pod-name-passing-example-
spec:
  entrypoint: main
  templates:
  - name: main
    steps:
    - - name: get-pod-name
        template: get-pod-name
    - - name: use-pod-name
        template: use-pod-name
        arguments:
          parameters:
          - name: pod-name
            value: "{{steps.get-pod-name.outputs.parameters.pod-name}}"

  - name: get-pod-name
    outputs:
      parameters:
      - name: pod-name
        value: "{{pod.name}}"
    container:
      image: alpine:3.7
      command: [sh, -c]
      args: ["echo Capturing pod name"]

  - name: use-pod-name
    inputs:
      parameters:
      - name: pod-name
    container:
      image: alpine:3.7
      command: [sh, -c]
      args: ["echo Step 1 Pod Name is {{inputs.parameters.pod-name}}"]

Another approach could be extracting pod metadata from environment variables:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: pod-metadata-env-
spec:
  entrypoint: main
  templates:
  - name: main
    container:
      image: alpine:3.7
      command: [sh, -c]
      args: ["echo Pod Name: $MY_POD_NAME && echo Namespace: $MY_POD_NAMESPACE && echo Pod IP: $MY_POD_IP"]
      env:
      - name: MY_POD_NAME
        valueFrom:
          fieldRef:
            fieldPath: metadata.name
      - name: MY_POD_NAMESPACE
        valueFrom:
          fieldRef:
            fieldPath: metadata.namespace
      - name: MY_POD_IP
        valueFrom:
          fieldRef:
            fieldPath: status.podIP
    nodeSelector:
      kubernetes.io/os: linux

What would be best practice in this case, either these or some other approach?

For reference, the question is motivated by Argo’s apparent lack of support for Windows daemon containers.