Support both build-time and run-time values for WEBAPP_URL. Improve re-build time, if just the WEBAPP_URL is changed.

Dockerfile

@@ -8,9 +8,7 @@ ARG NEXTAUTH_SECRET=secret
 ARG CALENDSO_ENCRYPTION_KEY=secret
 ARG MAX_OLD_SPACE_SIZE=4096
 
-# PLACEHOLDER value is compiled in during build, but will be replaced it at runtime
+ENV NEXT_PUBLIC_WEBAPP_URL=http://NEXT_PUBLIC_WEBAPP_URL_PLACEHOLDER \
-#             see: scripts/replace-placeholders.sh
-ENV NEXT_PUBLIC_WEBAPP_URL=https://NEXT_PUBLIC_WEBAPP_URL_PLACEHOLDER \
     NEXT_PUBLIC_LICENSE_CONSENT=$NEXT_PUBLIC_LICENSE_CONSENT \
     CALCOM_TELEMETRY_DISABLED=$CALCOM_TELEMETRY_DISABLED \
     DATABASE_URL=$DATABASE_URL \
@@ -30,6 +28,8 @@ RUN yarn build
 FROM node:16 as runner
 
 WORKDIR /calcom
+ARG NEXT_PUBLIC_WEBAPP_URL=http://localhost:3000
+
 ENV NODE_ENV production
 
 RUN apt-get update && \
@@ -44,5 +44,12 @@ COPY --from=builder /calcom/apps/web ./apps/web
 COPY --from=builder /calcom/packages/prisma/schema.prisma ./prisma/schema.prisma
 COPY scripts scripts
 
+# Save value used during this build stage. If NEXT_PUBLIC_WEBAPP_URL and BUILT_NEXT_PUBLIC_WEBAPP_URL differ at
+# run-time, then start.sh will find/replace static values again.
+ENV NEXT_PUBLIC_WEBAPP_URL=$NEXT_PUBLIC_WEBAPP_URL \
+    BUILT_NEXT_PUBLIC_WEBAPP_URL=$NEXT_PUBLIC_WEBAPP_URL
+
+RUN scripts/replace-placeholder.sh http://NEXT_PUBLIC_WEBAPP_URL_PLACEHOLDER ${NEXT_PUBLIC_WEBAPP_URL}
+
 EXPOSE 3000
 CMD ["/calcom/scripts/start.sh"]

README.md

@@ -112,7 +112,7 @@ Updating these variables is not required for evaluation, but is required for run
 
 | Variable | Description | Required | Default |
 | --- | --- | --- | --- |
-| NEXT_PUBLIC_WEBAPP_URL | Base URL injected into static files | required | `http://localhost:3000` |
+| NEXT_PUBLIC_WEBAPP_URL | Base URL injected into static files | optional | `http://localhost:3000` |
 | NEXT_PUBLIC_LICENSE_CONSENT | license consent - true/false |  |  |
 | CALCOM_TELEMETRY_DISABLED | Allow cal.com to collect anonymous usage data (set to `1` to disable) | | |
 | DATABASE_URL | database url with credentials | required | `postgresql://unicorn_user:magical_password@database:5432/calendso` |
@@ -125,6 +125,7 @@ These variables must also be provided at runtime
 
 | Variable | Description | Required | Default |
 | --- | --- | --- | --- |
+| NEXT_PUBLIC_WEBAPP_URL | Base URL of the site.  NOTE: if this value differs from the value used at build-time, there will be a slight delay during container start (to update the statically built files). | optional | `http://localhost:3000` |
 | CALCOM_LICENSE_KEY | Enterprise License Key |  |  |
 | NEXTAUTH_SECRET | must match build variable | required | `secret` |
 | CALENDSO_ENCRYPTION_KEY | must match build variable | required | `secret` |

scripts/replace-placeholder.sh

@@ -0,0 +1,16 @@
+FROM=$1
+TO=$2
+
+if [ "${FROM}" = "${TO}" ]; then
+    echo "Nothing to replace, the value is already set to ${TO}."
+
+    exit 0
+fi
+
+# Only peform action if $FROM and $TO are different.
+echo "Replacing all statically built instances of $FROM with $TO."
+
+find apps/web/.next/ apps/web/public -type f |
+while read file; do
+    sed -i "s|$FROM|$TO|g" "$file"
+done

scripts/replace-placeholders.sh

@@ -1,5 +0,0 @@
-# Find and replace placeholder values with runtime-specific environment values
-find apps/web/.next/ apps/web/public -type f |
-while read file; do
-    sed -i "s|https://NEXT_PUBLIC_WEBAPP_URL_PLACEHOLDER|$NEXT_PUBLIC_WEBAPP_URL|g" "$file"
-done

scripts/start.sh

@@ -1,7 +1,10 @@
 #!/bin/sh
 set -x
 
-scripts/replace-placeholders.sh
+# Replace the statically built BUILT_NEXT_PUBLIC_WEBAPP_URL with run-time NEXT_PUBLIC_WEBAPP_URL
+# NOTE: if these values are the same, this will be skipped.
+scripts/replace-placeholder.sh "$BUILT_NEXT_PUBLIC_WEBAPP_URL" "$NEXT_PUBLIC_WEBAPP_URL"
+
 scripts/wait-for-it.sh ${DATABASE_HOST} -- echo "database is up"
 npx prisma migrate deploy --schema /calcom/packages/prisma/schema.prisma
 npx ts-node --transpile-only /calcom/packages/prisma/seed-app-store.ts