Double proxy (with
This sandbox demonstrates a basic “double proxy” configuration, in which a simple Flask app connects to a PostgreSQL database, with two Envoy proxies in between.
Envoy (front) ->
Envoy (postgres-front) ->
Envoy (postgres-back) ->
This type of setup is common in a service mesh where Envoy acts as a “sidecar” between individual services.
It can also be useful as a way of providing access for application servers to upstream services or databases that may be in a different location or subnet, outside of a service mesh or sidecar-based setup.
Another common use case is with Envoy configured to provide “Points of presence” at the edges of the cloud, and to relay requests to upstream servers and services.
This example encrypts the transmission of data between the two middle proxies and provides mutual authentication
This can be useful if the proxies are physically separated or transmit data over untrusted networks.
In order to use the sandbox you will first need to generate the necessary
SSL keys and certificates.
This example walks through creating a certificate authority, and using it to create a domain key and sign certificates for the proxies.
Change to the
Step 2: Create a domain key¶
Create a key for the example domain:
$ openssl genrsa -out certs/example.com.key 2048 Generating RSA private key, 2048 bit long modulus (2 primes) ..+++++ .................................................+++++ e is 65537 (0x010001)
Step 3: Generate certificate signing requests for the proxies¶
Use the domain key to generate certificate signing requests for each of the proxies:
$ openssl req -new -sha256 \ -key certs/example.com.key \ -subj "/C=US/ST=CA/O=MyExample, Inc./CN=proxy-postgres-frontend.example.com" \ -out certs/proxy-postgres-frontend.example.com.csr $ openssl req -new -sha256 \ -key certs/example.com.key \ -subj "/C=US/ST=CA/O=MyExample, Inc./CN=proxy-postgres-backend.example.com" \ -out certs/proxy-postgres-backend.example.com.csr
Step 4: Sign the proxy certificates¶
You can now use the certificate authority that you created to sign the certificate requests.
subjectAltName. This is used for reciprocally matching and validating the certificates.
$ openssl x509 -req \ -in certs/proxy-postgres-frontend.example.com.csr \ -CA certs/ca.crt \ -CAkey certs/ca.key \ -CAcreateserial \ -extfile <(printf "subjectAltName=DNS:proxy-postgres-frontend.example.com") \ -out certs/postgres-frontend.example.com.crt \ -days 500 \ -sha256 Signature ok subject=C = US, ST = CA, O = "MyExample, Inc.", CN = proxy-postgres-frontend.example.com Getting CA Private Key $ openssl x509 -req \ -in certs/proxy-postgres-backend.example.com.csr \ -CA certs/ca.crt \ -CAkey certs/ca.key \ -CAcreateserial \ -extfile <(printf "subjectAltName=DNS:proxy-postgres-backend.example.com") \ -out certs/postgres-backend.example.com.crt \ -days 500 \ -sha256 Signature ok subject=C = US, ST = CA, O = "MyExample, Inc.", CN = proxy-postgres-backend.example.com Getting CA Private Key
At this point you should have the necessary keys and certificates to secure the connection between the proxies.
The keys and certificates are stored in the
Step 5: Start all of our containers¶
Build and start the containers.
This will load the required keys and certificates into the frontend and backend proxies.
$ pwd envoy/examples/double-proxy $ docker-compose build --pull $ docker-compose up -d $ docker-compose ps Name Command State Ports -------------------------------------------------------------------------------------------------------- double-proxy_app_1 python3 /code/service.py Up double-proxy_postgres_1 docker-entrypoint.sh postgres Up 5432/tcp double-proxy_proxy-frontend_1 /docker-entrypoint.sh /usr ... Up 0.0.0.0:10000->10000/tcp double-proxy_proxy-postgres-backend_1 /docker-entrypoint.sh /usr ... Up 10000/tcp double-proxy_proxy-postgres-frontend_1 /docker-entrypoint.sh /usr ... Up 10000/tcp
Step 6: Check the flask app can connect to the database¶
Checking the response at http://localhost:10000, you should see the output from the Flask app:
$ curl -s http://localhost:10000 Connected to Postgres, version: PostgreSQL 13.0 (Debian 13.0-1.pgdg100+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit