🧾 Environment Variables and ccptaskid

This page documents special environment variables made available during method execution.
These allow your code to uniquely identify each replica, manage security tokens, and interact with D4Science services.

πŸ”€ ccptaskid: Execution Replica Identifier

When a method is executed in parallel (e.g. multiple inputs or parallel containers), each instance is assigned a unique ccptaskid.

You can use this to generate replica-specific outputs:

mkdir -p /ccp_data/output
echo $RANDOM > /ccp_data/output/$(printenv ccptaskid).txt

This ensures files don’t overwrite each other across replicas.

πŸ” Auth Environment Variables

When your method runs, the container receives the following secure environment variables:

Variable Description
ccpiamurl IAM server URL
ccpclientid Client ID for token operations
ccprefreshtoken Refresh token for authentication
ccpcontext VRE/Context in which the method runs

πŸ”„ Renewing Tokens from Inside the Method

You can use these variables to request a login token and an UMA access token
for accessing secured services like the Workspace or Catalogue.

🐍 Example: Token Renewal in Python

import os, requests

# Get auth info
refreshtoken = os.environ["ccprefreshtoken"]
context = os.environ["ccpcontext"]
clientid = os.environ["ccpclientid"]
iam = os.environ["ccpiamurl"]

# Login request
logindata = {
  'grant_type': 'refresh_token',
  'client_id': clientid,
  'refresh_token': refreshtoken
}
loginheaders = {
  "Accept": "application/json",
  "Content-Type": "application/x-www-form-urlencoded"
}

# UMA token request
umadata = {
  'grant_type': 'urn:ietf:params:oauth:grant-type:uma-ticket',
  'audience': context
}
umaheaders = {
  "Accept": "application/json",
  "Content-Type": "application/x-www-form-urlencoded"
}

def getToken():
    resp1 = requests.post(iam, data=logindata, headers=loginheaders)
    jwt = resp1.json()
    umaheaders["Authorization"] = "Bearer " + jwt["access_token"]
    resp2 = requests.post(iam, data=umadata, headers=umaheaders)
    return resp2.json()["access_token"]

# Use token
token = getToken()
headers = {"Authorization": f"Bearer {token}", "Accept": "application/json"}
vrefolder = requests.get("https://workspace.d4science.org/vrefolder", headers=headers).json()