Fail gracefully when executed from main

Author: mads-hartmann

dev/BUILD.yaml

@@ -31,12 +31,4 @@ packages:
 scripts:
   - name: preview
     description: Build Gitpod, create a preview environment, and deploy to it
-    script: |
-      export TF_INPUT=0
-      export TF_IN_AUTOMATION=true
-      source "preview/workflow/lib/ensure-gcloud-auth.sh"
-      ensure_gcloud_auth
-      leeway run dev/preview:create-preview
-      leeway run dev/preview:build
-      previewctl install-context
-      leeway run dev/preview:deploy-gitpod
+    script: ./preview/workflow/preview/preview.sh

dev/preview/workflow/lib/git.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+# this script is meant to be sourced
+
+function git:branch-name {
+    git rev-parse --abbrev-ref HEAD
+}
+
+function git:is-on-main {
+    if [[ "$(git:branch-name)" == "main" ]]
+    then return 0
+    else return 1
+    fi
+}

dev/preview/workflow/preview/preview.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# shellcheck disable=1091
+
+set -euo pipefail
+
+ROOT="$(realpath "$(dirname "$0")")/../../../../"
+
+source "${ROOT}/dev/preview/workflow/lib/ensure-gcloud-auth.sh"
+source "${ROOT}/dev/preview/workflow/lib/common.sh"
+source "${ROOT}/dev/preview/workflow/lib/git.sh"
+
+# Don't prompt user before terraform apply
+export TF_INPUT=0
+export TF_IN_AUTOMATION=true
+
+if git:is-on-main; then
+    log_error "We don't support running dev:preview from the main branch. Please switch to another branch."
+    exit 1
+fi
+
+ensure_gcloud_auth
+
+leeway run dev/preview:create-preview
+leeway run dev/preview:build
+previewctl install-context
+leeway run dev/preview:deploy-gitpod