Merge pull request #89 from Joxit/custom-headers

Supports custom headers when the ui is used as proxy

## Background

Headers can be useful in some cases such as avoid sending credentials when you are on the UI (like #87). Or give to the registry server other properties such as `X-Forward-For` or `Server` headers for monitoring.

## How to use ?

This is compatible only with static version of the UI and used with `REGISTRY_URL` variable.
When you want to add a custom header, add to the registry ui a environment variable or entry in `/etc/nginx/.env` which looks like `NGINX_PROXY_HEADER_Custom_Header`. All underscores (`_`) will be replaced by hyphens (`-`). 

Some example of custom headers as variable:
- `NGINX_PROXY_HEADER_Authorization` for Basic auth credentials
- `NGINX_PROXY_HEADER_X_Forwarded_For` for identifying the originating IP address of a client

An example is bundled with this PR

closes: #87

bin/entrypoint

@@ -1,5 +1,5 @@
 #!/bin/sh
-$@
+
 sed -i "s,\${URL},${URL}," scripts/docker-registry-ui.js
 sed -i "s,\${REGISTRY_TITLE},${REGISTRY_TITLE}," scripts/docker-registry-ui.js
 sed -i "s,\${PULL_URL},${PULL_URL}," scripts/docker-registry-ui.js
@@ -8,13 +8,31 @@ if [ -z "${DELETE_IMAGES}" ] || [ "${DELETE_IMAGES}" = false ] ; then
   sed -i -r "s/(isImageRemoveActivated[:=])[^,;]*/\1false/" scripts/docker-registry-ui.js
 fi
 
+get_nginx_proxy_headers() {
+  (
+    env &&
+    if [ -f "/etc/nginx/.env" ]; then
+      cat /etc/nginx/.env
+      # Force new line
+      echo ""
+    fi
+  ) | while read e; do
+    if [ -n "$(echo $e | grep -o '^NGINX_PROXY_HEADER_')" ]; then
+      key=$(echo ${e%%=*} | sed 's/^NGINX_PROXY_HEADER_//' | sed 's/_/-/g')
+      value=${e#*=}
+      echo -n "proxy_set_header ${key} \"${value}\"; "
+    fi
+  done
+}
+
 if [ -n "${REGISTRY_URL}" ] ; then
   sed -i "s,\${REGISTRY_URL},${REGISTRY_URL}," /etc/nginx/conf.d/default.conf
+  sed -i "s^\${NGINX_PROXY_HEADERS}^$(get_nginx_proxy_headers)^" /etc/nginx/conf.d/default.conf
   sed -i "s,#!,," /etc/nginx/conf.d/default.conf
 fi
 
 if [ -z "$@" ]; then
-  nginx -g "daemon off;"
+  exec nginx -g "daemon off;"
 else
-  $@
+  exec $@
 fi

examples/proxy-headers/README.md

@@ -0,0 +1,19 @@
+# Set custom headers to the registry example
+
+The interface and the docker registry will be accessible with <http://localhost>.
+
+This example highlight the usage of custom headers when the UI is used as a proxy. When you wants to use a header name with hyphens, replace them by underscores in the variable. You can put headers in environment variable or in config file `/etc/nginx/.env`. They have the same writing style.
+
+Headers can be useful in some cases such as avoid sending credentials when you are on the UI. Or give to the registry server other properties such as X-Forward-For header.
+
+I will set these two headers in this example. X-Forward-For by environment variable and Authorization by file.
+
+In order to set your credentials in the header, you need to know how [Authorization](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Authorization) header works. Here we use the `Basic` authentication scheme, the credentials are constructed like this:
+- The username and the password are combined with a colon (`registry:ui`).
+- The resulting string is base64 encoded (`cmVnaXN0cnk6dWk=`). You can simply run `echo -n "registry:ui" | base64`.
+- In your header, put this value `Basic cmVnaXN0cnk6dWk=`
+- In your `/etc/nginx/.env`, the file will contains `NGINX_PROXY_HEADER_Authorization=Basic cmVnaXN0cnk6dWk=`
+
+For X-Forward-For, replace all hyphens by underscores, and the value will be a nginx variable which is `$proxy_add_x_forwarded_for`. In your docker compose you will need to duplicate the `$` character. In your docker-compose, your environment will look like `NGINX_PROXY_HEADER_X_Forwarded_For=$$proxy_add_x_forwarded_for`
+
+As usual, run the project with `docker-compose up -d` (for background mode)

examples/proxy-headers/docker-compose.yml

@@ -0,0 +1,28 @@
+version: '2.0'
+services:
+  registry:
+    image: registry:2.7
+    volumes:
+      - ./registry-data:/var/lib/registry
+      - ./registry-config/credentials.yml:/etc/docker/registry/config.yml
+      - ./registry-config/htpasswd:/etc/docker/registry/htpasswd
+    networks:
+      - registry-ui-net
+
+  ui:
+    image: joxit/docker-registry-ui:static
+    ports:
+      - 80:80
+    environment:
+      - REGISTRY_TITLE=My Private Docker Registry
+      - REGISTRY_URL=http://registry:5000
+      - NGINX_PROXY_HEADER_X_Forwarded_For=$$proxy_add_x_forwarded_for
+    volumes:
+      - ./nginx.env:/etc/nginx/.env
+    depends_on:
+      - registry
+    networks:
+      - registry-ui-net
+
+networks:
+  registry-ui-net:

examples/proxy-headers/nginx.env

@@ -0,0 +1 @@
+NGINX_PROXY_HEADER_Authorization=Basic cmVnaXN0cnk6dWk=

examples/proxy-headers/registry-config/credentials.yml

@@ -0,0 +1,25 @@
+version: 0.1
+log:
+  fields:
+    service: registry
+storage:
+  delete:
+    enabled: true
+  cache:
+    blobdescriptor: inmemory
+  filesystem:
+    rootdirectory: /var/lib/registry
+http:
+  addr: :5000
+  headers:
+    X-Content-Type-Options: [nosniff]
+    Access-Control-Allow-Origin: ['http://localhost']
+    Access-Control-Allow-Methods: ['HEAD', 'GET', 'OPTIONS', 'DELETE']
+    Access-Control-Allow-Headers: ['Authorization']
+    Access-Control-Max-Age: [1728000]
+    Access-Control-Allow-Credentials: [true]
+    Access-Control-Expose-Headers: ['Docker-Content-Digest']
+auth:
+  htpasswd:
+    realm: basic-realm
+    path: /etc/docker/registry/htpasswd

examples/proxy-headers/registry-config/htpasswd

@@ -0,0 +1 @@
+registry:$2y$11$1bmuJLK8HrQl5ACS/WeqRuJLUArUZfUcP2R23asmozEpfN76.pCHy

nginx/default.conf

@@ -25,6 +25,7 @@ server {
 #!            return 404;
 #!        }
 #!        proxy_set_header Host $http_host;
+#!        ${NGINX_PROXY_HEADERS}
 #!        proxy_pass ${REGISTRY_URL};
 #!    }
 

package.json

@@ -14,7 +14,7 @@
   "dependencies": {},
   "devDependencies": {
     "del": "^3.0.0",
-    "gulp": "^4.0.1",
+    "gulp": "^4.0.2",
     "gulp-clean-css": "^4.2.0",
     "gulp-concat": "^2.6.0",
     "gulp-filter": "^5.1.0",