Develop Pulsar Functions in Golang(Private Preview)
This section introduces how to develop and pacakge Golang Pulsar functions to use on StreamNative cloud.
We provide a different Golang runtime other than the community one, and it’s still in private preview stage, If you want to try it out or have any questions, please submit a ticket to the support team.
We provide a GO SDK for developing Golang Pulsar Functions.
The following examples use Pulsar Functions SDK for the Golang language.
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package mainimport ( "context" "fmt" "strings" "github.com/streamnative/pulsar-function-go/pf" "github.com/sirupsen/logrus")func HandleExclamation(ctx context.Context, in []byte) ([]byte, error) { // 1. unmarshal []byte to your struct, use any schema you want payload := string(in) // 2. do your logic if fc, ok := pf.FromContext(ctx); ok { for _, word := range strings.Split(payload, " ") { // 2.1 Incr and Get Counter from state store _ = fc.IncrCounter(word, 1) count, _ := fc.GetCounter(word) // 2.2 Sending logs to a Pulsar topic logrus.Infof("got word: %s for %d times", word, count) } // 2.3 Get user-defined configurations cfg := fc.GetUserConfValue("configKey") // 2.4 Get secret configurations sec, err := fc.GetSecret("secretKey") if err == nil { msg := fmt.Sprintf("config: %v, secret: %s", cfg, *sec) // 2.5 Publish to any topic _, _ = fc.Publish("persistent://public/default/test-exec-package-serde-extra", []byte(msg)) } } data := payload + "!" // 3. marshal your struct to []byte return []byte(data), nil}func main() { pf.Start(HandleExclamation)}
After creating a cluster, set up your environment and develop&package your function, you can use the snctl, pulsarctl, pulsar-admin command, the REST API, or terraform to deploy a Pulsar function to your cluster.
You can create a Golang Pulsar function by using a local compiled Golang file or an uploaded Pulsar functions package(recommend).
We are using a different Golang runtime, need to specify the --custom-runtime-options '{"genericKind": "executable"}' to make it work.
Init the terraform provider in the same dir of your .tf file if you haven’t done it:
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terraform init
You should see something like this:
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Initializing the backend...Initializing provider plugins...- Finding streamnative/pulsar versions matching "0.2.0"...- Installing streamnative/pulsar v0.2.0...- Installed streamnative/pulsar v0.2.0 (self-signed, key ID 3105E1011F3C3671)Partner and community providers are signed by their developers.If you'd like to know more about provider signing, you can read about it here:https://www.terraform.io/docs/cli/plugins/signing.htmlTerraform has created a lock file .terraform.lock.hcl to record the providerselections it made above. Include this file in your version control repositoryso that Terraform can guarantee to make the same selections by default whenyou run "terraform init" in the future.Terraform has been successfully initialized!You may now begin working with Terraform. Try running "terraform plan" to seeany changes that are required for your infrastructure. All Terraform commandsshould now work.If you ever set or change modules or backend configuration for Terraform,rerun this command to reinitialize your working directory. If you forget, othercommands will detect it and remind you to do so if necessary.
Create the function:
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terraform apply
You should see something like:
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Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols: + createTerraform will perform the following actions: # pulsar_function.function-1 will be created + resource "pulsar_function" "function-1" { + auto_ack = true + classname = "exclamation.ExclamationFunction" + cleanup_subscription = true + cpu = 0.5 + custom_runtime_options = jsonencode( { + genericKind = "executable", + env = { + HELLO = "WORLD" } } ) + dead_letter_topic = "public/default/dlt" + disk_mb = 128 + forward_source_message_property = true + id = (known after apply) + inputs = [ + "persistent://public/default/test-go-input", ] + go = "function://public/default/go-exclamation@v0.1" + log_topic = "public/default/lt" + max_message_retries = 100 + name = "function1" + namespace = "default" + output = "persistent://public/default/test-go-output" + parallelism = 1 + processing_guarantees = "ATLEAST_ONCE" + ram_mb = 128 + retain_key_ordering = true + secrets = jsonencode( { + SECRET1 = { + key = "hello" + path = "sectest" } } ) + skip_to_latest = true + subscription_name = "test-sub" + subscription_position = "Latest" + tenant = "public" + timeout_ms = 6666 }Plan: 1 to add, 0 to change, 0 to destroy.Do you want to perform these actions? Terraform will perform the actions described above. Only 'yes' will be accepted to approve. Enter a value:
We are using a different Golang runtime, need to specify the --custom-runtime-options '{"genericKind": "executable"}' to make it work.
The function is assumed to be already uploaded at this point. If you have not
uploaded the function, change the url parameter to be your local filepath.
This will look something like the following.
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-F 'url=file://$YOUR_LCOAL_FUNCTION_FILE'
You should see something like this:
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Created successfully
Replace the placeholder variables with the actual values that you can get when setting up client tools.
WEB_SERVICE_URL: the HTTPS service URL of your Pulsar cluster.
TOKEN: a valid token to interact with your Pulsar cluster.
FUNCTION_NAME: the name of your function.
FUNCTION_VERSION: the version of your function you want to deploy e.g. 1.12.