add config templating

Author: saltydk

Dockerfile

@@ -30,4 +30,8 @@ ENV ALLOW_RESTARTS=0 \
     TASKS=0 \
     VERSION=1 \
     VOLUMES=0
-COPY haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg
+RUN apk add --no-cache gettext
+COPY docker-entrypoint.sh /
+COPY haproxy.cfg /usr/local/etc/haproxy/haproxy.cfg.template
+
+ENTRYPOINT ["/docker-entrypoint.sh"]

docker-entrypoint.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+set -e
+
+# Normalize the input for ENABLE_IPV6 to lowercase
+ENABLE_IPV6_LOWER=$(echo "$ENABLE_IPV6" | tr '[:upper:]' '[:lower:]')
+
+# Check for different representations of 'true' and set BIND_CONFIG
+case "$ENABLE_IPV6_LOWER" in
+    1|true|yes)
+        BIND_CONFIG="[::]:2375 v4v6"
+        ;;
+    *)
+        BIND_CONFIG=":2375"
+        ;;
+esac
+
+# Export BIND_CONFIG for envsubst
+export BIND_CONFIG
+
+# Process the HAProxy configuration template
+envsubst < /usr/local/etc/haproxy/haproxy.cfg.template > /usr/local/etc/haproxy/haproxy.cfg
+cat /usr/local/etc/haproxy/haproxy.cfg
+
+# Command-line argument handling
+if [ "${1#-}" != "$1" ]; then
+    set -- haproxy "$@"
+fi
+
+if [ "$#" -eq 0 ] || [ "$1" = 'haproxy' ]; then
+    if [ "$1" = 'haproxy' ]; then
+        shift
+    fi
+    set -- haproxy -W -db -f /usr/local/etc/haproxy/haproxy.cfg "$@"
+fi
+
+exec "$@"

haproxy.cfg

@@ -44,7 +44,7 @@ backend docker-events
     timeout server 0
 
 frontend dockerfrontend
-    bind :::2375 v4v6
+    bind ${BIND_CONFIG}
     http-request deny unless METH_GET || { env(POST) -m bool }
     http-request allow if { path,url_dec -m reg -i ^(/v[\d\.]+)?/containers/[a-zA-Z0-9_.-]+/((stop)|(restart)|(kill)) } { env(ALLOW_RESTARTS) -m bool }
     http-request allow if { path,url_dec -m reg -i ^(/v[\d\.]+)?/containers/[a-zA-Z0-9_.-]+/start } { env(ALLOW_START) -m bool }