Added support for multiple upstream DNS servers (#25)

Dockerfile.alpine

@@ -41,7 +41,7 @@ USER nobody
 # Set environment defaults
 # We are using OpenDNS DNS server address as default
 # Here is the list of addresses: https://use.opendns.com/
-ENV UPSTREAM_DNS_SERVER="udp:208.67.222.222:53"
+ENV UPSTREAM_DNS_SERVER="udp:208.67.222.222:53,udp:208.67.220.220:53"
 ENV DOH_HTTP_PREFIX="/getnsrecord"
 ENV DOH_SERVER_LISTEN=":8053"
 ENV DOH_SERVER_TIMEOUT="10"

Dockerfile.ubuntu

@@ -56,7 +56,7 @@ USER nobody
 # Set environment defaults
 # We are using OpenDNS DNS server address as default
 # Here is the list of addresses: https://use.opendns.com/
-ENV UPSTREAM_DNS_SERVER="udp:208.67.222.222:53"
+ENV UPSTREAM_DNS_SERVER="udp:208.67.222.222:53,udp:208.67.220.220:53"
 ENV DOH_HTTP_PREFIX="/getnsrecord"
 ENV DOH_SERVER_LISTEN=":8053"
 ENV DOH_SERVER_TIMEOUT="10"

Makefile

@@ -62,7 +62,7 @@ test-all:
 	$(L)${MAKE} run-tests IMAGE=${IMAGE_TEST} TAGNAME=${TAGNAME}
 
 run-tests:
-	$(L)cd tests; pipenv install --python 3.10
+	$(L)cd tests; pipenv install --python 3.12
 	$(L)cd tests; pipenv run python ./test-doh-server.py --image ${IMAGE}:${TAGNAME}-alpine
 
 # Commands:

docker-entrypoint

@@ -29,6 +29,18 @@ do
     printf "| ENTRYPOINT: Exporting var: $varName\n"
 done
 
+# If UPSTREAM_DNS_SERVER contains a comma (i.e., multiple servers are provided)
+if [[ "$UPSTREAM_DNS_SERVER" == *","* ]]; then
+    # Convert the comma-separated list into a valid array for the config file
+    upstream_servers=$(echo "$UPSTREAM_DNS_SERVER" | sed 's/,/","/g')
+    upstream_servers="[\"$upstream_servers\"]"
+else
+    # If only a single DNS server is provided, use it as before
+    upstream_servers="[\"$UPSTREAM_DNS_SERVER\"]"
+fi
+
+export upstream_servers
+
 # lets generate config file by replacing all variables inside of it.
 TMP_FILE=/tmp/doh-server.conf
 cp ${DOH_CONFIG_SAMPLE_FILE} ${TMP_FILE}

doh-server.sample.conf

@@ -40,7 +40,7 @@ path = "${DOH_HTTP_PREFIX}"
 #     "udp:8.8.8.8:53",
 #     "udp:8.8.4.4:53",
 # ]
-upstream = [ "${UPSTREAM_DNS_SERVER}" ]
+upstream = ${upstream_servers}
 
 # Upstream timeout
 # timeout = 10

tests/Pipfile

@@ -10,4 +10,4 @@ requests = "*"
 [dev-packages]
 
 [requires]
-python_version = "3.10"
+python_version = "3.12"