vertex ai agent builder deploy langchain app
We will be using google colab to demostrate the deployment of a simple app to Vertex AI agent builder
Create your notebook and then run the following codes
!pip install --upgrade --quiet google-cloud-aiplatform[agent_engines,langchain]>=1.112
Next we will do some authentication and initialization
import vertexai
vertexai.init(
project="project-xxxxxxx", # Your project ID.
location="us-central1",
staging_bucket="gs://staging-bucket" # Replace with your GCS bucket
)
client = vertexai.Client(
project="project-xxxxxxxxx", # Your project ID.
location="us-central1"
)
Creating a simple function
def get_exchange_rate(
currency_from: str = "USD",
currency_to: str = "EUR",
currency_date: str = "latest",
):
"""Retrieves the exchange rate between two currencies on a specified date."""
import requests
response = requests.get(
f"https://api.frankfurter.app/{currency_date}",
params={"from": currency_from, "to": currency_to},
)
return response.json()
And invoking the tool using gemini-flash
from vertexai import agent_engines
agent = agent_engines.LanggraphAgent(
model="gemini-2.0-flash",
tools=[get_exchange_rate],
model_kwargs={
"temperature": 0.28,
"max_output_tokens": 1000,
"top_p": 0.95,
},
)
Getting response from the agent
remote_agent.query(input={
"messages": [
("user", "What is the exchange rate from US dollars to SEK today?"),
]
})
Let's deploy our agent and you can see we are specifying some dependencies. You may run
into some dependencies issues with module versioning. So something to take note
remote_agent = agent_engines.create(
agent,
requirements=[
"google-cloud-aiplatform[agent_engines,langchain]==1.140.0",
"pydantic==2.12.3",
"cloudpickle==3.1.2"
]
)
After the deployment you might want to test it out
agent.query(input={"messages": [
("user", "What is the exchange rate from US dollars to SEK today?"),
]})
Troubleshooting
If you run into an error like this here - you might need to use a different region that
supports the model.
"404 Publisher Model
`projects/project-xxxxxxx/locations/asia-southeast1/publishers/
google/models/gemini-2.5-flash-lite` was not found or your project
does not have access to it"
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