Fix Cerebras API authentication error
api_error Why this happens
The authentication error arises when the Cerebras client is not properly initialized with a valid API key or when the base_url is missing or incorrect. For example, using the OpenAI SDK without specifying the Cerebras API endpoint or forgetting to set the CEREBRAS_API_KEY environment variable triggers an authentication failure.
Typical error output:
openai.error.AuthenticationError: No API key provided or invalid API key
from openai import OpenAI
import os
client = OpenAI() # Missing api_key and base_url
response = client.chat.completions.create(
model="llama3.3-70b",
messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)openai.error.AuthenticationError: No API key provided or invalid API key
The fix
Initialize the Cerebras client with the API key loaded from the environment variable CEREBRAS_API_KEY. If using the OpenAI-compatible client, specify the base_url as https://api.cerebras.ai/v1. This ensures proper authentication and endpoint targeting.
This works because the client sends the API key in the request headers and directs requests to the correct Cerebras API endpoint.
from openai import OpenAI
import os
client = OpenAI(
api_key=os.environ["CEREBRAS_API_KEY"],
base_url="https://api.cerebras.ai/v1"
)
response = client.chat.completions.create(
model="llama3.3-70b",
messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)Hello! How can I assist you today?
Preventing it in production
Use environment variables to securely manage API keys and never hardcode them. Implement retry logic with exponential backoff to handle transient authentication or network errors. Validate the presence of CEREBRAS_API_KEY at application startup to fail fast if missing. Monitor API usage and error rates to detect authentication issues early.
Key Takeaways
- Always set the Cerebras API key via the
CEREBRAS_API_KEYenvironment variable. - Use the OpenAI-compatible client with the correct
base_urlfor Cerebras API calls. - Implement retries and validate API key presence to avoid authentication failures in production.