gcsproxy

Reverse proxy for Google Cloud Storage.

Description

This is a reverse proxy for Google Cloud Storage for performing limited disclosure (IP address restriction etc...). Gets the URL of the GCS object through its internal API. Therefore, it is possible to make GCS objects private and deliver limited content.

 +---------------------------------------+
 |                Nginx                  |
 |    access control (basic auth/ip)     |
 +-----+---------------------------------+
       |
-----------------------------------------+
       |
       |
+------v-----+          +---------------+
|            |          |               |
|  gcsproxy  | +------> | Google Cloud  |
|            |          |    Storage    |
+------------+          +---------------+

Usage

Usage of gcsproxy:
  -b string
        Bind address (default "127.0.0.1:8080")
  -c string
        The path to the keyfile. If not present, client will use your default application credentials.
  -i string
        The default index file to serve.
  -v    Show access log

The gcsproxy routing configuration is shown below.

"/{bucket:[0-9a-zA-Z-_.] +}/{object:. *}"

If you are running gcsproxy on localhost:8080 and you want to access the file gs://test-bucket/your/file/path.txt in GCS via gcsproxy, you can use the URL You can access the file via gcsproxy at the URL http://localhost:8080/test-bucket/your/file/path.txt.

If a default index file is specified and the target object does not exist, an attempt is made to retrieve the object specified in the default index file.

gcsproxy -i index.html

http://localhost:8080/test-bucket/foo/bar
#=> gs://test-bucket/foo/bar/index.html

Configurations

Dockerfile example

FROM debian:buster-slim AS build

WORKDIR /tmp
ENV GCSPROXY_VERSION=0.3.1

RUN apt-get update \
    && apt-get install --no-install-suggests --no-install-recommends --yes ca-certificates wget \
    && wget https://github.com/daichirata/gcsproxy/releases/download/v${GCSPROXY_VERSION}/gcsproxy-${GCSPROXY_VERSION}-linux-amd64.tar.gz \
    && tar zxf gcsproxy-${GCSPROXY_VERSION}-linux-amd64.tar.gz \
    && cp ./gcsproxy-${GCSPROXY_VERSION}-linux-amd64/gcsproxy .

FROM gcr.io/distroless/base
COPY --from=build /tmp/gcsproxy /gcsproxy
CMD ["/gcsproxy"]

Docker image build example

docker build --build-arg GCSPROXY_VERSION=0.4.0 -t gcsproxy .

Example how to run the image

The d53ee11da87c.json JSON files contains the Google Cloud Service Account credentials.

docker run \
    -it --rm \
    -p 8080:80 \
    -e GOOGLE_APPLICATION_CREDENTIALS=/cred.json \
    -v $(pwd)/../d53ee11da87c.json:/cred.json gcsproxy 

Docker Compose example

version: '3.3'

networks:
  web:

services:
  gcsproxy:
    build:
      context: .
      dockerfile: Dockerfile
      args:
        GCSPROXY_VERSION: 0.4.0
        #HTTPS_PROXY: http://192.168.1.1:8080/
        #HTTP_PROXY: http://192.168.1.1:8080/
    restart: unless-stopped
    networks:
      - "web"
    ports:
      - 8080:80
    command: -b 0.0.0.0:80 -c /cred.json
    #environment:
      #HTTPS_PROXY: http://192.168.1.1:8080/
      #HTTP_PROXY: http://192.168.1.1:8080/
    volumes:
      - ./d53ee11da87c.json:/cred.json

systemd example

[Unit]
Description=gcsproxy

[Service]
Type=simple
ExecStart=/opt/gcsproxy/gcsproxy -v
ExecStop=/bin/kill -SIGTERM $MAINPID

[Install]
WantedBy = multi-user.target

nginx.conf

upstream gcsproxy {
    server '127.0.0.1:8080';
}

server {
    listen 8081;
    server_name _;

    # Logs
    access_log off;
    error_log /var/log/nginx/gcsproxy.error.log error;

    if ($request_method !~ "GET|HEAD|PURGE") {
        return 405;
    }

    location / {
        proxy_pass http://gcsproxy$uri;
    }
}