First API Call

7 min

Your First API Call

A 60-second sanity check: get a token, hit one endpoint, see a 200.

Run this call live: every example on this page also lives in the Litmus API collection. Open the collection, fork it, paste your token, and hit Send.

1. Get a token

TOKEN=$(curl -sk -X POST "https://<edge-host>/auth/v3/oauth/token" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "grant_type=client_credentials" \
  -d "client_id=$CLIENT_ID" \
  -d "client_secret=$CLIENT_SECRET" | jq -r .access_token)

-k skips TLS verification - use only against self-signed dev instances. See SSL Certificates before doing this in production.

2. Call a read-only endpoint

curl -sk "https://<edge-host>/devicehub/version" \
  -H "Authorization: Bearer $TOKEN"

Expected: a JSON object with a Version field. If you see this, auth and routing work.

3. Try a GraphQL call

DeviceHub is GraphQL. List drivers on the edge:

curl -sk -X POST "https://<edge-host>/devicehub/v2" \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"query":"query { ListDriverGroups { ID Name Drivers { ID Name } } }"}'

GraphQL endpoints return HTTP 200 even on errors. Check the errors key in the response body, not just the status code. See GraphQL vs REST.

Python equivalent

import os, requests

EDGE = os.environ["EDGE_URL"]
r = requests.post(
    f"{EDGE}/auth/v3/oauth/token",
    data={
        "grant_type": "client_credentials",
        "client_id": os.environ["CLIENT_ID"],
        "client_secret": os.environ["CLIENT_SECRET"],
    },
    verify=False,
)
token = r.json()["access_token"]

v = requests.get(f"{EDGE}/devicehub/version",
                 headers={"Authorization": f"Bearer {token}"},
                 verify=False)
print(v.json())

Troubleshooting

Symptom	Likely cause
401 Unauthorized	Token expired, wrong client_id/secret, or wrong header (LEM uses X-AuthToken, not Bearer)
404 Not Found	Wrong base URL or path prefix - see Base URLs
SSL: CERTIFICATE_VERIFY_FAILED	Self-signed cert - see SSL Certificates
GraphQL returns 200 but no data	Check errors key in the body, not just HTTP status