Help Center/ FunctionGraph/ User Guide (ME-Abu Dhabi Region)/ Getting Started/ Deploying a Function Using a Container Image/ Developing an Event Function
Updated on 2023-11-21 GMT+08:00
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Developing an Event Function

Introduction

When developing an event function using a custom image, implement an HTTP server in the image and listen on port 8000 for requests. By default, the request path /init is the function initialization entry. Implement it as required. The request path /invoke is the function execution entry where trigger events are processed. For details about request parameters, see Supported Event Sources.

Step 1: Prepare the Environment

To perform the operations described in this section, ensure that you have the FunctionGraph FullAccess permissions, that is, all permissions for FunctionGraph. For more information, see Permissions Management.

Step 2: Create an Image

Take the Linux x86 64-bit OS as an example.

  1. Create a folder. 
    mkdir custom_container_event_example && cd custom_container_event_example
  1. Implement an HTTP server to process init and invoke requests and give a response. Node.js is used as an example.

    Create the main.js file to introduce the Express framework and implement a function handler (method POST and path /invoke and an initializer (method POST and path /init).

    const express = require('express'); 
 
const PORT = 8000; 
 
const app = express(); 
app.use(express.json());
 
app.post('/init', (req, res) => { 
  console.log('receive', req.body);
  res.send('Hello init\n'); 
}); 
 
app.post('/invoke', (req, res) => { 
  console.log('receive', req.body);
  res.send('Hello invoke\n'); 
}); 
 
app.listen(PORT, () => { 
  console.log(`Listening on http://localhost:${PORT}`); 
});
  1. Create the package.json file for npm so that it can identify the project and process project dependencies. 
    {
  "name": "custom-container-event-example",
  "version": "1.0.0",
  "description": "An example of a custom container event function",
  "main": "main.js",
  "scripts": {},
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
      "express": "^4.17.1"
  }
}
    • name: project name
    • version: project version
    • main: application entry file
    • dependencies: all available dependencies of the project in npm
  2. Create a Dockerfile. 
    FROM node:12.10.0

ENV HOME=/home/custom_container
ENV GROUP_ID=1003
ENV GROUP_NAME=custom_container
ENV USER_ID=1003
ENV USER_NAME=custom_container

RUN mkdir -m 550 ${HOME} && groupadd -g ${GROUP_ID} ${GROUP_NAME} && useradd -u ${USER_ID} -g ${GROUP_ID} ${USER_NAME}

COPY --chown=${USER_ID}:${GROUP_ID} main.js ${HOME}
COPY --chown=${USER_ID}:${GROUP_ID} package.json ${HOME}

RUN cd ${HOME} && npm install

RUN chown -R ${USER_ID}:${GROUP_ID} ${HOME}

RUN find ${HOME} -type d | xargs chmod 500
RUN find ${HOME} -type f | xargs chmod 500

USER ${USER_NAME}
WORKDIR ${HOME}

EXPOSE 8000
ENTRYPOINT ["node", "main.js"]
    • FROM: Specify base image node:12.10.0. The base image is mandatory and its value can be changed.
    • ENV: Set environment variables HOME (/home/custom_container), GROUP_NAME and USER_NAME (custom_container), USER_ID and GROUP_ID (1003). These environment variables are mandatory and their values can be changed.
    • RUN: Use the format RUN <Command>. For example, RUN mkdir -m 550 ${HOME}, which means to create the home directory for user ${USER_NAME} during container building.
    • USER: Switch to user ${USER_NAME}.
    • WORKDIR: Switch the working directory to the home directory of user ${USER_NAME}.
    • COPY: Copy main.js and package.json to the home directory of user ${USER_NAME} in the container.
    • EXPOSE: Expose port 8000 of the container. Do not change this parameter.
    • ENTRYPOINT: Run the node /home/tester/main.js command to start the container.
    1. You can use any base image.
    2. In the cloud environment, UID 1003 and GID 1003 are used to start the container by default. The two IDs can be modified by choosing Configuration > Basic Settings > Container Image Override on the function details page. They cannot be root or a reserved ID.
  1. Build an image.

    In the following example, the image name is custom_container_event_example, the tag is latest, and the period (.) indicates the directory where the Dockerfile is located. Run the image build command to pack all files in the directory and send the package to a container engine to build an image.

    docker build -t custom_container_event_example:latest .

Step 3: Perform Local Verification

  1. Start the Docker container. 
    docker run -u 1003:1003 -p 8000:8000 custom_container_event_example:latest
  1. Open a new Command Prompt, and send a message through port 8000 to access the /init directory specified in the template code. 
    curl -XPOST -H 'Content-Type: application/json' localhost:8000/init

    The following information is returned based on the module code:

    Hello init
  1. Open a new Command Prompt, and send a message through port 8000 to access the /invoke directory specified in the template code. 
    curl -XPOST -H 'Content-Type: application/json' -d '{"message":"HelloWorld"}' localhost:8000/invoke

    The following information is returned based on the module code:

    Hello invoke
  1. Check whether the following information is displayed: 
    Listening on http://localhost:8000
receive {}
receive { message: 'HelloWorld' }

    Alternatively, run the docker logs command to obtain container logs.

Step 4: Upload the Image

  1. Log in to the SWR console. In the navigation pane, choose My Images.
  2. Click Upload Through Client or Upload Through SWR in the upper right corner.
  3. Upload the image as prompted.

  4. View the image on the My Images page.

Step 5: Create a Function

  1. In the left navigation pane of the management console, choose Compute > FunctionGraph. On the FunctionGraph console, choose Functions > Function List from the navigation pane.
  2. Click Create Function in the upper right corner and choose Container Image.
  3. Set the basic information.
    • Function Type: Select Event Function.
    • Function Name: Enter custom_container_event.
    • Container Image: Select the image uploaded to SWR.
    • Agency: Select an agency with the SWR Admin permission. If no agency is available, create one by referring to Creating an Agency.
  4. After the configuration is complete, click Create Function.
  5. On the function details page, choose Configuration > Advanced Settings, and enable Initialization. The init API will be called to initialize the function.

Step 6: Test the Function

  1. On the function details page, click Test. In the displayed dialog box, create a test event.
  2. Select blank-template, set Event Name to helloworld, modify the test event as follows, and click Create. 
    {
    "message": "HelloWorld"
}

Step 7: View the Execution Result

Click Test and view the execution result on the right.

Figure 1 Execution result
  • Function Output: displays the return result of the function.
  • Log Output: displays the execution logs of the function.
  • Summary: displays key information of the logs.

    A maximum of 2 KB logs can be displayed. For more log information, see Querying Function Logs.

Step 8: View Monitoring Metrics

On the function details page, click the Monitoring tab.

  • On the Monitoring tab page, choose Metrics, and select a time range (such as 5 minutes, 15 minutes, or 1 hour) to query the function.
  • The following metrics are displayed: invocations, errors, duration (including the maximum, average, and minimum durations), and throttles.

Step 9: Delete the Function

  1. On the function details page, choose Operation > Delete Function in the upper right corner.
  2. In the displayed dialog box, click OK to release resources.