Add initial Tilt support

Signed-off-by: Andy Goldstein <andy.goldstein@redhat.com>

.dockerignore

@@ -5,3 +5,4 @@ bin/goreleaser
 bin/kustomize
 bin/envtest
 testbin/
+.tiltbuild/

.gitignore

@@ -12,3 +12,5 @@ bin/
 dist/
 cover.out
 catalogd.yaml
+
+.tiltbuild/

Tiltfile

@@ -0,0 +1,66 @@
+# This loads a helper function that isn't part of core Tilt that simplifies restarting the process in the container
+# when files changes.
+load('ext://restart_process', 'docker_build_with_restart')
+
+# Treat the main binary as a local resource, so we can automatically rebuild it when any of the deps change. This
+# builds it locally, targeting linux, so it can run in a linux container.
+local_resource(
+    'manager_binary',
+    cmd='''
+mkdir -p .tiltbuild/bin
+CGO_ENABLED=0 GOOS=linux go build -o .tiltbuild/bin/manager ./cmd/manager
+''',
+    deps=['api', 'cmd/manager', 'internal', 'pkg', 'go.mod', 'go.sum']
+)
+
+# Configure our image build. If the file in live_update.sync (.tiltbuild/bin/manager) changes, Tilt
+# copies it to the running container and restarts it.
+docker_build_with_restart(
+    # This has to match an image in the k8s_yaml we call below, so Tilt knows to use this image for our Deployment,
+    # instead of the actual image specified in the yaml.
+    ref='quay.io/operator-framework/catalogd:devel',
+    # This is the `docker build` context, and because we're only copying in the binary we've already had Tilt build
+    # locally, we set the context to the directory containing the binary.
+    context='.tiltbuild/bin',
+    # We use a slimmed-down Dockerfile that only has $binary in it.
+    dockerfile_contents='''
+FROM gcr.io/distroless/static:debug
+EXPOSE 8080
+WORKDIR /
+COPY manager manager
+''',
+    # The set of files Tilt should include in the build. In this case, it's just the binary we built above.
+    only='manager',
+    # If .tiltbuild/bin/manager changes, Tilt will copy it into the running container and restart the process.
+    live_update=[
+        sync('.tiltbuild/bin/manager', '/manager'),
+    ],
+    # The command to run in the container.
+    entrypoint="/manager",
+)
+
+# Tell Tilt what to deploy by running kustomize and then doing some manipulation to make things work for Tilt.
+objects = decode_yaml_stream(kustomize('config/default'))
+for o in objects:
+    # For Tilt's live_update functionality to work, we have to run the container as root. Remove any PSA labels to allow
+    # this.
+    if o['kind'] == 'Namespace' and 'labels' in o['metadata']:
+        labels_to_delete = [label for label in o['metadata']['labels'] if label.startswith('pod-security.kubernetes.io')]
+        for label in labels_to_delete:
+            o['metadata']['labels'].pop(label)
+
+    if o['kind'] != 'Deployment':
+        # We only need to modify Deployments, so we can skip this
+        continue
+
+    # For Tilt's live_update functionality to work, we have to run the container as root. Otherwise, Tilt won't
+    # be able to untar the updated binary in the container's file system (this is how live update
+    # works). If there are any securityContexts, remove them.
+    if "securityContext" in o['spec']['template']['spec']:
+        o['spec']['template']['spec'].pop('securityContext')
+    for c in o['spec']['template']['spec']['containers']:
+        if "securityContext" in c:
+            c.pop('securityContext')
+
+# Now apply all the yaml
+k8s_yaml(encode_yaml_stream(objects))

tilt.md

@@ -0,0 +1,75 @@
+# Rapid iterative development with Tilt
+
+[Tilt](https://tilt.dev) is a tool that enables rapid iterative development of containerized workloads.
+
+Here is an example workflow without Tilt for modifying some source code and testing those changes in a cluster:
+
+1. Modify the source code.
+2. Build the container image.
+3. Either push the image to a registry or load it into your kind cluster.
+4. Deploy all the appropriate Kubernetes manifests for your application.
+    1. Or, if this is an update, you'd instead scale the Deployment to 0 replicas, scale back to 1, and wait for the
+       new pod to be running.
+
+This process can take minutes, depending on how long each step takes.
+
+Here is the same workflow with Tilt:
+
+1. Run `tilt up`
+2. Modify the source code
+3. Wait for Tilt to update the container with your changes
+
+This ends up taking a fraction of the time, sometimes on the order of a few seconds!
+
+## Installing Tilt
+
+Follow Tilt's [instructions](https://docs.tilt.dev/install.html) for installation.
+
+## Starting Tilt
+
+This is typically as short as:
+
+```shell
+tilt up
+```
+
+**NOTE:** if you are using Podman, at least as of v4.5.1, you need to do this:
+
+```shell
+DOCKER_BUILDKIT=0 tilt up
+```
+
+Otherwise, you'll see an error when Tilt tries to build your image that looks similar to:
+
+```text
+Build Failed: ImageBuild: stat /var/tmp/libpod_builder2384046170/build/Dockerfile: no such file or directory
+```
+
+When Tilt starts, you'll see something like this in your terminal:
+
+```text
+Tilt started on http://localhost:10350/
+v0.33.1, built 2023-06-28
+
+(space) to open the browser
+(s) to stream logs (--stream=true)
+(t) to open legacy terminal mode (--legacy=true)
+(ctrl-c) to exit
+```
+
+Typically, you'll want to press the space bar to have it open the UI in your web browser.
+
+Shortly after starting, Tilt processes the `Tiltfile`, resulting in:
+
+- Building the go binaries
+- Building the images
+- Loading the images into kind
+- Running kustomize and applying everything except the Deployments that reference the images above
+- Modifying the Deployments to use the just-built images
+- Creating the Deployments
+
+## Making code changes
+
+Any time you change any of the files listed in the `deps` section in the `<binary name>_binary` `local_resource`,
+Tilt automatically rebuilds the go binary. As soon as the binary is rebuilt, Tilt pushes it (and only it) into the
+appropriate running container, and then restarts the process.