From f4fb75610a5e0196ef5291b36047df4884b32f4f Mon Sep 17 00:00:00 2001
From: Ian Fijolek <ian@iamthefij.com>
Date: Tue, 13 Jan 2026 21:43:57 -0800
Subject: [PATCH] Update variable interpolation for hcl

---
 README.md         | 4 +++-
 sample-config.hcl | 8 ++++----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 01b3872..843eb0e 100644
--- a/README.md
+++ b/README.md
@@ -50,7 +50,9 @@ You can configure the timezone for the container by passing a `TZ` env variable.
 
 ## Configuring
 
-In this repo, you can explore the `sample-config.hcl` file for an example, but the general structure is as follows. It should be noted that environment variable interpolation happens on load of the HCL file.
+In this repo, you can explore the `sample-config.hcl` file for an example, but the general structure is as follows. If you are passing environment variables to your commands or alerts, you should be aware that `${VAR}` syntax is reserved for HCL variable interpolation. To avoid issues, you can use `$${VAR}` syntax to escape the `$` character, simply use `$VAR`.
+
+```hcl
 
 The global configurations are:
 
diff --git a/sample-config.hcl b/sample-config.hcl
index e102dd9..f5a2c01 100644
--- a/sample-config.hcl
+++ b/sample-config.hcl
@@ -38,15 +38,15 @@ alert "mailgun_down" {
     -F to=me@minitor.mon \
     -F text="Our monitor failed" \
     https://api.mailgun.net/v3/minitor.mon/messages \
-    -u "api:${MAILGUN_API_KEY}"
+    -u "api:$${MAILGUN_API_KEY}"
   EOF
 }
 
 alert "sms_down" {
   shell_command = <<-EOF
   curl -s -X POST -F "Body=Failure! {{.MonitorName}} has failed" \
-    -F "From=${AVAILABLE_NUMBER}" -F "To=${MY_PHONE}" \
-    "https://api.twilio.com/2010-04-01/Accounts/${ACCOUNT_SID}/Messages" \
-    -u "${ACCOUNT_SID}:${AUTH_TOKEN}"
+    -F "From=$${AVAILABLE_NUMBER}" -F "To=$${MY_PHONE}" \
+    "https://api.twilio.com/2010-04-01/Accounts/$${ACCOUNT_SID}/Messages" \
+    -u "$${ACCOUNT_SID}:$${AUTH_TOKEN}"
   EOF
 }