Merge pull request #87 from coderbydesign/dynamic-resolver

Use dynamic resolver from /etc/resolv.conf

.env.example

@@ -4,3 +4,4 @@ SECRET_KEY=
 FLASK_ENV=development
 MULTI_VALUE_SAML_ATTRS=Role
 AUTH_DEBUG=1
+TURNPIKE_ALLOWED_ORIGIN_DOMAINS=web,echo-server,foo,host.docker.internal

.pre-commit-config.yaml

@@ -2,7 +2,7 @@ default_language_version:
   python: python3.8
 repos:
 - repo: https://github.com/psf/black
-  rev: 19.3b0
+  rev: 22.3.0
   hooks:
   - id: black
     args: ["-l", "119", "-t", "py38"]

dev-backends.yml

@@ -4,6 +4,12 @@
   auth:
     saml: "True"
     x509: "True"
+- name: rbac
+  route: /api/rbac
+  origin: http://host.docker.internal:8000/_private/api
+  auth:
+    saml: "True"
+    x509: "True"
 - name: healthcheck
   route: /public/healthcheck/
   origin: http://web.svc.cluster.local:5000/_healthcheck/
@@ -19,3 +25,6 @@
   origin: http://echo-server.svc.cluster.local:8080/
   source_ip:
     - 240.0.0.0/4
+- name: nginx_regression_test
+  route: /api/does_not_exist/
+  origin: http://foo:5000/does_not_exist/

nginx/backend_template.conf.j2

@@ -1,10 +1,12 @@
-    location {{ route }} {
+    location ~ {{ route }}(.*)$ {
+        resolver {{ resolver }} valid=60s;
+        set $upstream  {{ origin }};
         auth_request     /auth/;
         auth_request_set $login_url $upstream_http_login_url;
         {% for header in headers %}
         auth_request_set $turnpike_{{ header.lower().replace("-", "_") }} $upstream_http_{{ header.lower().replace("-", "_") }};
         {% endfor %}
-        proxy_pass              {{ origin }};
+        proxy_pass              $upstream$1$is_args$args;
         proxy_set_header        X-Original-URI $request_uri;
         proxy_set_header        X-Real-IP $remote_addr;
         proxy_set_header        X-Forwarded-Host $proxy_host;

nginx/build_config.py

@@ -3,6 +3,7 @@
 import argparse
 import json
 import os
+import re
 import time
 from urllib import parse, request, error
 import warnings
@@ -47,6 +48,18 @@ def validate_route(backend):
     return True
 
 
+def get_resolver():
+    resolver_file_name = "/etc/resolv.conf"
+    file = open(resolver_file_name, "r")
+    match = re.search("(?<=nameserver )(.*)(?=\\n)", file.read())
+    if not match:
+        raise Exception(f"Error getting resolver from {resolver_file_name}")
+
+    resolver = match.group()
+    print(f"Using resolver: {resolver}")
+    return resolver
+
+
 def main(args):
     try:
         with open(args.config_map_path) as ifs:
@@ -77,6 +90,7 @@ def main(args):
     headers_to_upstream = nginx_config["to_upstream"]
     headers_to_policy_service = nginx_config["to_policy_service"]
     blueprints = nginx_config["blueprints"]
+    resolver = get_resolver()
 
     with open("/etc/nginx/api_gateway.conf.j2") as ifs:
         template = jinja2.Template(ifs.read())
@@ -90,7 +104,7 @@ def main(args):
         print(f"Processing backend configuration for {name}")
         if validate_route(backend):
             with open(f"/etc/nginx/api_conf.d/{name}.conf", "w") as ofs:
-                ofs.write(template.render(headers=headers_to_upstream, **backend))
+                ofs.write(template.render(headers=headers_to_upstream, resolver=resolver, **backend))
     print("Done.")