🌉 Add ngrok tunnel in Tiltfile

dockercoins/Tiltfile

@@ -1,14 +1,58 @@
+# (1) Setting up a registry, and telling Tilt to use it.
+
+# Tilt needs a registry to store images.
+
+# The following manifest defines a Deployment to run a basic Docker registry,
+# and a NodePort Service to access it. Using a NodePort means that we don't
+# need to obtain a TLS certificate, because we will be accessing the registry
+# through localhost.
 k8s_yaml('../k8s/tilt-registry.yaml')
+
+# Tell Tilt to use the registry that we just deployed instead of whatever
+# is defined in our Kubernetes resources. Tilt will patch image names to
+# use our registry.
 default_registry('localhost:30555')
+
+# Create a port forward so that we can access the registry from our local
+# environment, too. Note that if you run Tilt directly from a Kubernetes node
+# (which is not typical, but might happen in some lab/training environments)
+# the following might cause an error because port 30555 is already taken.
+k8s_resource(workload='tilt-registry', port_forwards='30555:5000')
+
+# (2) Telling Tilt how to build and run our app.
+
+# Our Kubernetes manifests use images 'dockercoins/...' so we tell Tilt
+# how each of these images should be built. The first argument is the name
+# of the image, the second argument is the directory containing the build
+# context (i.e. the Dockerfile to build the image).
 docker_build('dockercoins/hasher', 'hasher')
 docker_build('dockercoins/rng', 'rng')
 docker_build('dockercoins/webui', 'webui')
 docker_build('dockercoins/worker', 'worker')
+
+# The following manifests defines five Deployments and four Services for
+# our application.
 k8s_yaml('../k8s/dockercoins.yaml')
 
-# Uncomment the following line to let tilt run with the default kubeadm cluster-admin context.
-#allow_k8s_contexts('kubernetes-admin@kubernetes')
+# (3) Finishing touches.
 
-# While we're here: if you're controlling a remote cluster, uncomment that line.
-# It will create a port forward so that you can access the remote registry.
-#k8s_resource(workload='registry', port_forwards='30555:5000')
+# The following line lets Tilt run with the default kubeadm cluster-admin context.
+allow_k8s_contexts('kubernetes-admin@kubernetes')
+
+# This will run an ngrok tunnel to expose Tilt to the outside world.
+# This is intended to be used when Tilt runs on a remote machine.
+local_resource(name='ngrok:tunnel', serve_cmd='ngrok http 10350')
+
+# This will wait until the ngrok tunnel is up, and show its URL to the user.
+# We send the output to /dev/tty so that it doesn't get intercepted by
+# Tilt, and gets displayed to the user's terminal instead.
+# Note: this assumes that the ngrok instance will be running on port 4040.
+# If you have other ngrok instances running on the machine, this might not work.
+local_resource(name='ngrok:showurl', cmd='''
+  while sleep 1; do
+    TUNNELS=$(curl -fsSL http://localhost:4040/api/tunnels | jq -r .tunnels[].public_url)
+    [ "$TUNNELS" ] && break
+  done
+  printf "\nYou should be able to connect to the Tilt UI with the following URL(s): %s\n" "$TUNNELS" >/dev/tty
+  '''
+)

slides/k8s/tilt.md

@@ -193,26 +193,44 @@ Ah, right ...
 
 ---
 
-## Running Tilt
+## Running Tilt locally
 
-- If you're running on your local machine:
+*These instructions are valid only if you run Tilt on your local machine.*
+
+*If you are running Tilt on a remote machine or in a Pod, see next slide.*
+
+- Start Tilt:
   ```bash
   tilt up
   ```
-  Then press "space" or connect to http://localhost:10350/
 
-- If you're running on a remote machine:
-  ```bash
-  tilt up --host=0.0.0.0
-  ```
-  Then connect to the remote machine on port 10350
-
-- The Tilt web interface might complain about the Kubernetes context
-
-  ...If it does, don't worry, we'll fix that right away!
+- Then press "space" or connect to http://localhost:10350/
 
 ---
 
+## Running Tilt on a remote machine
+
+- If Tilt runs remotely, we can't access http://localhost:10350
+
+- Our Tiltfile includes an ngrok tunnel, let's use that
+
+- Start Tilt:
+  ```bash
+  tilt up
+  ```
+
+- The ngrok URL should appear in the Tilt output
+
+  (something like `https://xxxx-aa-bb-cc-dd.ngrok.io/`)
+
+- Open that URL in your browser
+
+*Note: it's also possible to run `tilt up --host=0.0.0.0`.*
+
+---
+
+class: extra-details
+
 ## Kubernetes contexts
 
 - Tilt is designed to run in dev environments