Functions: Validate an API Key with API Gateway

• A paid Oracle Cloud Infrastructure account. See Signing Up for Oracle Cloud Infrastructure.
• Your OCI account configured to support Oracle Functions development. See Oracle Functions on Cloud Shell Quickstart.
• Completion of one of the two Oracle Functions introduction tutorials.
  • Functions: Get Started using Cloud Shell
  • Functions: Get Started using the CLI
• Completing one of the two tutorials results in:
  • Oracle Functions is set up and configured to create applications and deploy functions.
  • Oracle Registry is set up to store function images.
  • Docker is logged into the Oracle Registry.
  • The required VCN and required resources needed for Oracle Functions.
  • An API key pair and an auth token.

Oracle CLI

• Python 3.6+ and pip3.
• Docker Engine: A Linux computer or Linux VM. See Docker engine requirements for versions, and distros supported.
• Docker Desktop: Available for MacOS or Windows 10.
  • Windows 10: Windows 10 update 2004 with WSL 2 and Ubuntu or other distro installed.
    • See Windows Subsystem for Linux Installation Guide for Windows 10.
    • Install Docker Desktop for Windows 10.
    Note
    
    Docker includes special Linux support for WSL 2 on Windows 10 update 2004.
  • MacOS: See Install Docker Desktop for MacOS.

Oracle Cloud Shell

• If you use Cloud Shell, the preceding list of software is already installed.

To create a compartment see Create a compartment. After your compartment is created, save the compartment OCID and name.

To get the compartment OCID from an existing compartment:

1. Open the navigation menu and click Identity & Security. Under Identity, click Compartments.
2. Select your compartment.
3. Click the Copy link for the OCID field.

Save the compartment OCID and name.

Ensure you have the following information written down for the tutorial.

• Compartment Name: <your-compartment-name>

  Example: my-compartment

• Compartment ID: <your-compartment-OCID>

  Example: ocid1.compartment.oc1.aaaaaaa...

• VCN Name: <your-vcn-name>

  Example: my-vcn

  Open the navigation menu and click Networking, and then click Virtual Cloud Networks.

• VCN Public Subnet Name: <Public-Subnet-your-vcn-name>

  Example: Public-Subnet-my-vcn

  Open the navigation menu and click Networking, and then click Virtual Cloud Networks. Click on the VCN you created.

To create application, follow these steps.

1. Open the navigation menu and click Developer Services. Under Functions, click Applications.
2. Select your compartment from the Compartment drop-down.
3. Click Create Application.
4. Fill in the form data.
   • Name: <your-app-name>
   • VCN: <your-vcn-name>
   • Subnets: <Public-Subnet-your-vcn-name>
5. Click Create.

Your app is created.

1. Open the navigation menu and click Networking, and then click Virtual Cloud Networks.
2. Click the name of the VCN you used to for your Oracle Functions application.
3. With your new VCN displayed, click your Public subnet link.

   The public subnet information is displayed with the Security Lists at the bottom of the page.

4. Click the Default Security List link or appropriate security list link.

   The default Ingress Rules for your VCN are displayed.

5. Click Add Ingress Rules.

   An Add Ingress Rules dialog is displayed.

6. Fill in the ingress rule with the following information. After all the data is entered, click Add Ingress Rules

   Fill in the ingress rule as follows:

   • Stateless: Checked
   • Source Type: CIDR
   • Source CIDR: 0.0.0.0/0
   • IP Protocol: TCP
   • Source Port range: (leave-blank)
   • Destination Port Range: 443
   • Description: VCN for applications

   After you click Add Ingress Rule, HTTPS connections are allowed to your public subnet.

Next, setup a policy which allows API Gateway to invoke functions.

First, create a Dynamic Group for API Gateway.

1. Open the navigation menu and click Identity & Security. Under Identity, click Dynamic Groups.
2. Click Create Dynamic Group.
3. Fill in the following information to define your dynamic group.
   • Name: <name-for-your-dynamic-group>
   • Under Matching Rules use Rule 1: <the-rule-text>

   Here is sample name and the rule you need to fill out.

   • Name: api-gtw-func-dynamic-group
   • Under Matching Rules use Rule 1: ALL {resource.type = 'ApiGateway', resource.compartment.id = 'ocid1.compartment.<your-compartment-OCID>'}
4. Click Create.

Now create the policy for API Gateway.

1. Open the navigation menu and click Identity & Security. Under Identity, click Policies.
2. Click Create Policy.
3. To define your policy, fill in the following information.
   • Name: <name-for-your-policy>
   • Description: <description-for policy>
   • Compartment: <name-of-functions-compartment>

   For the Policy Builder section:

   • Click Show manual editor.
   • Enter your policy in the text box, for example:
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     Allow dynamic-group  api-gtw-func-dynamic-group to use functions-family in compartment <your-compartment-name>

     Note
     
     The last parameter is the compartment name, not the compartment OCID.
4. Click Create.

You have created a policy to allow API Gateway to use Functions.

1. Open a terminal.
2. Create a directory to store your functions and change into that directory.
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   mkdir my-dir-name
   cd my-dir-name                        
                        

3. Create a Python "Hello World" function with Fn.
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   fn init --runtime python my-func-name

   This command creates a directory named my-func-name with the function and configuration files in it.

4. Change into the directory.
5. Deploy the function.
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   fn -v deploy --app your-app-name

   Various messages are displayed as the Docker images are built, pushed to OCIR, and eventually deployed to Oracle Functions.

6. Invoke the function.
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   fn invoke your-app-name my-func-name

   Returns: {"message": "Hello World"}

7. Invoke the function with a parameter.
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   echo -n '{"name":"Bob"}' | fn invoke your-app-name my-func-name

   Returns: {"message": "Hello Bob"}

To create an API Gateway:

1. Open the navigation menu and click Developer Services. Under API Management, click Gateways.
2. Select your compartment from the Compartment drop-down.
3. Click Create Gateway
4. Fill in the following information to define your API Gateway.
   • Name: <your-gateway-name>
   • Type: <Public>
   • Compartment: <your-compartment-name>
   • Virtual Cloud Network in <your-vcn-name>: <select-your-vcn>
   • Subnet in <your-compartment-name: <your-public-subnet-name>
5. Click Create. Wait a few minutes for your API Gateway to e created.

Next, create a deployment for your API Gateway.

1. Click Deployments in Resources section on the left side of the screen.
2. Click Create Deployment.
3. Ensure that From Scratch is selected for the deployment type.
4. To define your deployment, fill in the Basic Information section.
   • Name: <your-deployment-name>
   • Path Prefix (example): /tokens
   • Compartment: <your-compartment-name>
   • API Request Policies: Take default values
   • API Logging Policies: Take default value of Information
5. Click Next. The Routes dialog appears with Route 1 selected.
6. To define your route, fill in the Route 1 section.
   • Path: <your-route-path>

     Example: /val-token

   • Methods: GET POST
   • Type: Oracle Functions
   • Application in <your-compartment-name>: Select the Functions application you created.
   • Function Name: Select the function you created in the configuration section.
7. Click Next. The Review dialog is displayed summarizing the choices you have made.
8. Click Create. Your deployment is created.
9. Click the Deployments link for your gateway. Copy the base end point for the deployment you created.

   For example: https://aaaaa.apigateway.us-ashburn-X.oci.customer-oic.com/tokens

With your API Gateway and deployment created, you can now test you installation. Create a simple script for the curl command. To create the URL for curl, add your deployment path to your endpoint.

1. Create the script file: touch gtw01.sh && chmod 755 gtw01.sh
2. Add the command curl command to the script file:
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   #!/bin/bash
   curl <your-api-gateway-endpoint>/val-token

3. The command returns: {"message":"Hello World"}

You have connected your API Gateway to a boiler plate Python function. Next, you update your Python function to display information passed in an HTTP request.

If you look at the boiler plate function, your Python function looks something like this.

import io
import json
import logging

from fdk import response


def handler(ctx, data: io.BytesIO = None):
    name = "World"
    try:
        body = json.loads(data.getvalue())
        name = body.get("name")
    except (Exception, ValueError) as ex:
        logging.getLogger().info('error parsing json payload: ' + str(ex))
    
    logging.getLogger().info("Inside Python Hello World function")
    return response.Response(
       ctx, response_data=json.dumps(
           {"message": "Hello {0}".format(name)}),
       headers={"Content-Type": "application/json"}
    )

Using this code as a starting point, the sections that follow convert the function into a Python function that validates an API key and returns a token.

Oracle Functions allows you to store configuration data in your context that is available in your request. Configuration data can be stored in an application or a function. The following command stores the API key in your app config.

• fn config app <your-app-name> FN_API_KEY ABCD

The "ABCD" string is a sample key value.

For more information about setting function configuration values, see Fn Project's tutorial on runtime context.

First, update the func.py for required packages.

1. Update the import statements in func.py for required packages validation:
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   import io
   import json
   import logging
   import datetime
   
   from datetime import timedelta
   from fdk import response
                   

   The datetime package is used to set an expiration time for the returned token.

2. Next, remove the main body of the function. The response method and related code are added back as we progress.
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   import io
   import json
   import logging
   import datetime
   
   from datetime import timedelta
   from fdk import response
                           
   
   def handler(ctx, data: io.BytesIO = None):                
   

Now you are ready to update the function with the validation code.

Next add code to validate the API key and return a token in the response. Here is the code with comments following.

import io
import json
import logging
import datetime

from datetime import timedelta
from fdk import response

def handler(ctx, data: io.BytesIO = None):
    auth_token = "invalid"
    token = "invalid"
    apiKey = "invalid"
    expiresAt = (datetime.datetime.utcnow() + timedelta(seconds=60)).replace(tzinfo=datetime.timezone.utc).astimezone().replace(microsecond=0).isoformat()
    
    try:
        auth_token = json.loads(data.getvalue())
        token = auth_token.get("token")
        
        app_context = dict(ctx.Config())
        apiKey = app_context['FN_API_KEY']
        
        if token == apiKey:
            return response.Response(
                ctx, 
                status_code=200, 
                response_data=json.dumps({"active": True, "principal": "foo", "scope": "bar", "clientId": "1234", "expiresAt": expiresAt, "context": {"username": "wally"}})
            )
    
    except (Exception, ValueError) as ex:
        logging.getLogger().info('error parsing json payload: ' + str(ex))
        pass
    
    return response.Response(
        ctx, 
        status_code=401, 
        response_data=json.dumps({"active": False, "wwwAuthenticate": "API-key"})
    )

• The handler function receives system information about the current request through the ctx and data parameters.
• The function assumes that FN_API_KEY is set in the app configuration. Then the function compares the configuration value to the token value sent from the curl POST request: -d '{"token":"ABCD"}'.
• If the values match, a validation JSON message is returned. If they do not match, a 401 code is returned with JSON error data.

The function code is complete. You are now ready to test the function.

1. Redeploy the updated function.
2. Invoke the function to ensure that the function is working.
3. Update the gtw01.sh script to pass the POST data to the script.
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   /bin/bash
   curl -X POST -d '{"token":"ABCD"}' https://aaaaa.apigateway.us-ashburn-X.oci.customer-oic.com/tokens/val-token

4. Run the script: gtw01.sh | jq
5. If the API keys match, the output from the script looks similar to:
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   {
       "active": true,
       "principal": "foo",
       "scope": "bar",
       "clientId": "1234",
       "expiresAt": "2020-12-16T22:48:50+00:00",
       "context": {
       "username": "wally"
       }
   }

   If the API keys do not match, an error message is returned.

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   {
       "active": false,
       "wwwAuthenticate": "API-key"
   }                        
                       

   You can download the complete source code for the function from the Oracle Function Samples site here.

Congratulations, you have converted the boiler plate Python function into a new function that validates an API key. The function demonstrates how data can be passed to API Gateway and processed in a function.