From 1791566764f9b0617d86eff2dadfbd225a4d619b Mon Sep 17 00:00:00 2001
From: SonOfLope <jonathan.lopez@inspection.gc.ca>
Date: Fri, 1 Nov 2024 14:16:24 -0400
Subject: [PATCH] Issue #65: prometheus dynamic config

---
 dockerfiles/prometheus/Dockerfile                   |  6 ++++--
 dockerfiles/prometheus/entrypoint.sh                | 13 +++++++++++++
 .../{prometheus.yaml => prometheus.yml.tmpl}        |  5 +----
 3 files changed, 18 insertions(+), 6 deletions(-)
 create mode 100755 dockerfiles/prometheus/entrypoint.sh
 rename dockerfiles/prometheus/{prometheus.yaml => prometheus.yml.tmpl} (59%)

diff --git a/dockerfiles/prometheus/Dockerfile b/dockerfiles/prometheus/Dockerfile
index d4ae09c..9f52211 100644
--- a/dockerfiles/prometheus/Dockerfile
+++ b/dockerfiles/prometheus/Dockerfile
@@ -1,5 +1,7 @@
 FROM prom/prometheus:latest
+COPY prometheus.yml.tmpl /etc/prometheus/prometheus.yml.tmpl
+COPY entrypoint.sh /entrypoint.sh
 
-COPY prometheus.yaml /etc/prometheus/prometheus.yml
+ENV ENABLE_BACKEND_METRICS=false
 
-CMD ["--config.file=/etc/prometheus/prometheus.yml", "--web.enable-remote-write-receiver"]
+ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/prometheus/entrypoint.sh b/dockerfiles/prometheus/entrypoint.sh
new file mode 100755
index 0000000..85bebd5
--- /dev/null
+++ b/dockerfiles/prometheus/entrypoint.sh
@@ -0,0 +1,13 @@
+#!/bin/sh
+
+if [ "$ENABLE_BACKEND_METRICS" = "true" ]; then
+  BACKEND_JOB="- job_name: 'backend'\n    metrics_path: '/metrics'\n    static_configs:\n      - targets: ['backend:5000']"
+else
+  BACKEND_JOB=""
+fi
+
+# Replace placeholder in the template
+sed "s|{{BACKEND_JOB}}|$BACKEND_JOB|" /etc/prometheus/prometheus.yml.tmpl > /etc/prometheus/prometheus.yml
+
+# Start Prometheus
+exec /bin/prometheus --config.file=/etc/prometheus/prometheus.yml --web.enable-remote-write-receiver
diff --git a/dockerfiles/prometheus/prometheus.yaml b/dockerfiles/prometheus/prometheus.yml.tmpl
similarity index 59%
rename from dockerfiles/prometheus/prometheus.yaml
rename to dockerfiles/prometheus/prometheus.yml.tmpl
index c5b34cc..415b49f 100644
--- a/dockerfiles/prometheus/prometheus.yaml
+++ b/dockerfiles/prometheus/prometheus.yml.tmpl
@@ -7,7 +7,4 @@ scrape_configs:
     static_configs:
       - targets: ['localhost:9090']
 
-  - job_name: 'backend'
-    metrics_path: '/metrics'
-    static_configs:
-      - targets: ['backend:5000']
+  {{BACKEND_JOB}}