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Functions development reference guide

OpenShift Serverless Functions provides templates that can be used to create basic functions. A template initiates the function project boilerplate and prepares it for use with the kn func tool. Each function template is tailored for a specific runtime and follows its conventions. With a template, you can initiate your function project automatically.

Templates for the following runtimes are available:

Node.js context object reference

The context object has several properties that can be accessed by the function developer. Accessing these properties can provide information about HTTP requests and write output to the cluster logs.

log

Provides a logging object that can be used to write output to the cluster logs. The log adheres to the Pino logging API.

Example log
function handle(context) {
  context.log.info(“Processing customer”);
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.function.com'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"Processing customer"}

You can change the log level to one of fatal, error, warn, info, debug, trace, or silent. To do that, change the value of logLevel by assigning one of these values to the environment variable FUNC_LOG_LEVEL using the config command.

query

Returns the query string for the request, if any, as key-value pairs. These attributes are also found on the context object itself.

Example query
function handle(context) {
  // Log the 'name' query parameter
  context.log.info(context.query.name);
  // Query parameters are also attached to the context
  context.log.info(context.name);
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.com?name=tiger'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"tiger"}

body

Returns the request body if any. If the request body contains JSON code, this will be parsed so that the attributes are directly available.

Example body
function handle(context) {
  // log the incoming request body's 'hello' parameter
  context.log.info(context.body.hello);
}

You can access the function by using the curl command to invoke it:

Example command
$ kn func invoke -d '{"Hello": "world"}'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"world"}

headers

Returns the HTTP request headers as an object.

Example header
function handle(context) {
  context.log.info(context.headers["custom-header"]);
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.function.com'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"some-value"}

HTTP requests

method

Returns the HTTP request method as a string.

httpVersion

Returns the HTTP version as a string.

httpVersionMajor

Returns the HTTP major version number as a string.

httpVersionMinor

Returns the HTTP minor version number as a string.

TypeScript context object reference

The context object has several properties that can be accessed by the function developer. Accessing these properties can provide information about incoming HTTP requests and write output to the cluster logs.

log

Provides a logging object that can be used to write output to the cluster logs. The log adheres to the Pino logging API.

Example log
export function handle(context: Context): string {
    // log the incoming request body's 'hello' parameter
    if (context.body) {
      context.log.info((context.body as Record<string, string>).hello);
    } else {
      context.log.info('No data received');
    }
    return 'OK';
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.function.com'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"Processing customer"}

You can change the log level to one of fatal, error, warn, info, debug, trace, or silent. To do that, change the value of logLevel by assigning one of these values to the environment variable FUNC_LOG_LEVEL using the config command.

query

Returns the query string for the request, if any, as key-value pairs. These attributes are also found on the context object itself.

Example query
export function handle(context: Context): string {
      // log the 'name' query parameter
    if (context.query) {
      context.log.info((context.query as Record<string, string>).name);
    } else {
      context.log.info('No data received');
    }
    return 'OK';
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.function.com' --data '{"name": "tiger"}'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"tiger"}
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"tiger"}

body

Returns the request body, if any. If the request body contains JSON code, this will be parsed so that the attributes are directly available.

Example body
export function handle(context: Context): string {
    // log the incoming request body's 'hello' parameter
    if (context.body) {
      context.log.info((context.body as Record<string, string>).hello);
    } else {
      context.log.info('No data received');
    }
    return 'OK';
}

You can access the function by using the kn func invoke command:

Example command
$ kn func invoke --target 'http://example.function.com' --data '{"hello": "world"}'
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"world"}

headers

Returns the HTTP request headers as an object.

Example header
export function handle(context: Context): string {
    // log the incoming request body's 'hello' parameter
    if (context.body) {
      context.log.info((context.headers as Record<string, string>)['custom-header']);
    } else {
      context.log.info('No data received');
    }
    return 'OK';
}

You can access the function by using the curl command to invoke it:

Example command
$ curl -H'x-custom-header: some-value’' http://example.function.com
Example output
{"level":30,"time":1604511655265,"pid":3430203,"hostname":"localhost.localdomain","reqId":1,"msg":"some-value"}

HTTP requests

method

Returns the HTTP request method as a string.

httpVersion

Returns the HTTP version as a string.

httpVersionMajor

Returns the HTTP major version number as a string.

httpVersionMinor

Returns the HTTP minor version number as a string.