spiffe-jwt/

README

HTTP over TLS with JWT

This example shows how two services using HTTP can communicate using TLS with the server presenting an X509 SVID and expecting a client to authenticate with a JWT-SVID. The SVIDs are retrieve, and authentication is accomplished, via the SPIFFE Workload API.

The HTTP server creates a workloadapi.X509Source.

source, err := workloadapi.NewX509Source(ctx, clientOptions)

The socket path is provided as a client option. If the socket path is not provided, the value from the SPIFFE_ENDPOINT_SOCKET environment variable is used.

source, err := workloadapi.NewX509Source(ctx)

The HTTP server then uses workloadapi.X509Source to create a tls.Config for TLS that will present the server X509-SVID.

The tls.Config is used when creating the HTTP server.

clientID := spiffeid.Must("example.org", "client")
tlsConfig := tlsconfig.TLSServerConfig(source)

server := &http.Server{
    Addr:      ":8443",
    TLSConfig: tlsConfig,
}

The server creates a JWTSource to obtain up-to-date JWT bundles from the Workload API.

jwtSource, err := workloadapi.NewJWTSource(ctx, clientOptions)

A middleware is added to authenticate client JWT-SVIDs provided in the Authorization header. This middleware validates token the token using the jwtsvid.ParseAndValidate using bundles obtained from the JWTSource.

svid, err := jwtsvid.ParseAndValidate(token, a.jwtSource, a.audiences)

As an alternative to verifying the JWT-SVIDs directly, the Workload API can also be used:

client, err := workloadapi.New(ctx)
if err != nil {
	log.Fatalf("Unable to connect to Workload API: %v", err)
}
svid, err := client.ValidateJWTSVID(ctx, token, audiences[0])

On the other side, the HTTP client uses the workloadapi.X509Source to create a tls.Config for TLS that authenticates the server certificate and verifies that it has the SPIFFE ID spiffe://examples.org/server.

serverID := spiffeid.Must("example.org", "server")
tlsConfig := tlsconfig.TLSClientConfig(source, tlsconfig.AuthorizeID(serverID))

client := &http.Client{
    Transport: &http.Transport{
        TLSClientConfig: tlsConfig,
    },
}

The client fetches a JWT-SVID from the Workload API (via the JWTSource) and adds it as a bearer token in the Authorization header.

svid, err := jwtSource.FetchJWTSVID(ctx, jwtsvid.Params{
	Audience: audience,
})
if err != nil {
    log.Fatalf("Unable to fetch SVID: %v", err)
}
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", svid.Marshal()))

That is it! The go-spiffe library fetches and automatically renews the X.509 SVID for the server and validates the client JWT SVIDs using the Workload API.

As soon as the TLS connection is established, the client sends an HTTP request to the server and gets a response.

Building

Build the client workload:

cd examples/spiffe-jwt/client
go build

Build the server workload:

cd examples/spiffe-jwt/server
go build

Running

This example assumes the following preconditions:

• There is a SPIRE server and agent up and running.
• There is a Unix workload attestor configured.
• The trust domain is example.org
• The agent SPIFFE ID is spiffe://example.org/host.
• There is a server-workload and client-workload user in the system.

1. Create the registration entries

Create the registration entries for the client and server workloads:

Server:

./spire-server entry create -spiffeID spiffe://example.org/server \
                            -parentID spiffe://example.org/host \
                            -selector unix:user:server-workload

Client:

./spire-server entry create -spiffeID spiffe://example.org/client \
                            -parentID spiffe://example.org/host \
                            -selector unix:user:client-workload

2. Start the server

Start the server with the server-workload user:

sudo -u server-workload ./server

3. Run the client

Run the client with the client-workload user:

sudo -u client-workload ./client

The server should display a log Request received and client Success!!!

To demonstrate a failure, an alternate audience value can be used. The server is expecting it's own SPIFFE ID as the audience value and will reject the token if it doesn't match.

sudo -u client-workload ./client spiffe://example.org/some-other-server

Unauthorized

When the token is rejected, the server log shows:

Invalid token: jwtsvid: expected audience in ["spiffe://example.org/server"] (audience=["spiffe://example.org/some-other-server"])