slack-command

Language	JavaScript
Function	slack_command.js
Protocol	HTTP
Input	slack
Output	none (replies, implicitly)

A Slack slash command is a custom integration enabling you to POST data to an external server by configuring a command that can be executed by prefixing the command name with the / character . This sample will demonstrate how to trigger a function from a Slack client. For example, if you configure a slash command named riff to launch this sample function, you can use a Slack client to post /riff riff is for functions to any channel in your Slack domain . If the command is successful, you will receive the expected response `"received:riff is for functions". To do this you need a Slack account.

Tip	There is a nice tutorial here.

Deploy the FaaS

Note	This example requires a Kubernetes cluster with LoadBalancer support and a public facing IP address such as GKE. Alternately, you can use an http tunnel such as ngrok.

Deploy riff with helm.

Running on minikube with ngrok

Once riff is running and ngrok is installed, get the URL of the http-gateway:

export NODE_PORT=$(kubectl get --namespace default -o jsonpath="{.spec.ports[0].nodePort}" services demo-riff-http-gateway)
export NODE_IP=$(kubectl get nodes --namespace default -o jsonpath="{.items[0].status.addresses[0].address}")
echo http://$NODE_IP:$NODE_PORT

You should see something like:

http://192.168.99.100:32595

In a separate terminal, start ngrok (substituting your actual URL):

ngrok http 192.168.99.100:32595

You should see some output including something like:

Forwarding                    http://a61d8bb0.ngrok.io -> 192.168.99.100:32595

Build the Docker container for the function code

eval $(minikube docker-env)
./riff build -n slack-command -v test -f samples/node/slack

Create the Function and Topic(s)

./riff apply -f samples/node/slack

Test the function locally

Slack slash commands POST x-www-form-urlencoded content with the posted content contained in text. To emulate this you can use curl (substituting your actual URL) to post some data to the slack topic:

curl -H "Content-Type:application/x-www-form-urlencoded" http://<ngrokid>.ngrok.io/requests/slack -d text='riff is for functions'
received:riff is for functions

Tip	You can use the local URL http://$NODE_IP:$NODE_PORT here, but a publicly accessible URL will be required for Slack integration.

Set up your Slack integration

Since the input topic configured for the function is named slack, configure the slash command to POST to http://<ngrokid>.ngrok.io/requests/slack.

Running on a Kubernetes cluster with LoadBalancer support (GKE)

Note

Running this sample on a cloud platform like GKE will require you to build and publish the image to a docker repository available to the platform. In GKE you can use the GCP Container Registry if it is enabled. Here we will assume dockerhub. You will need to tag the image you build accordingly. In these instructions, we refer to the tag as <your-docker-tag>. For dockerhub, this is typically something like <docker-user>/slack-command:test

Build the Docker container for the function code

docker build -t <your-docker-tag> samples/node/slack

Publish the image

docker push <your-docker-tag>

Create the Function and Topic(s)

Edit the local specification to replace the function container image with <your-docker-tag> and then

./riff apply -f samples/node/slack

Test the Function

Get the Gateway IP address and Port:

$ kubectl get svc -l component=http-gateway
NAME                     TYPE           CLUSTER-IP      EXTERNAL-IP       PORT(S)        AGE
riff-http-gateway        LoadBalancer   10.51.247.194   104.154.118.171   80:30725/TCP   22m

We can see from the EXTERNAL-IP and PORT(S) columns that our gateway is on http://104.154.118.171:80 in this case.

Another convenient way to get the URL is:

export GATEWAY_IP=$(kubectl get svc demo-riff-http-gateway -o jsonpath="{.status.loadBalancer.ingress[0].ip}")
export GATEWAY_PORT=$(kubectl get svc demo-riff-http-gateway -o jsonpath="{.spec.ports[0].port}")
echo http://$GATEWAY_IP:$GATEWAY_PORT

Invoke the function via curl

Slack slash commands POST x-www-form-urlencoded content with the posted content contained in text. To emulate this you can use curl (substituting your actual URL) to post some data to the slack topic:

curl -H "Content-Type:application/x-www-form-urlencoded" http://$GATEWAY_IP:$GATEWAY_PORT/requests/slack -d text='riff is for functions'
received:riff is for functions

Set up your Slack integration

Use the public Gateway IP URL To create your slack slash command. To POST to the slack topic, configure the slack command to use http://$GATEWAY_IP:$GATEWAY_PORT/requests/slack.

Delete your function

./riff delete -n slack-command