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gRPC proxy for your Oasis node

The Oasis node API is exposed via the gRPC protocol. It enables communication with external applications such as the Oasis CLI, dApps running in your browser that need to perform actions on the consensus layer or a ParaTime, services for monitoring and controlling your node and similar.

Web3 gateway

The Oasis gRPC is not related to the standardized Web3 JSON-RPC API. For EVM-compatible dApps configure a Web3 gateway instead which is also compatible with other Ethereum tooling.

The gRPC proxy may perform the following:

  • makes gRPC available to in-browser applications via gRPC-Web,
  • filters out control methods such as shutting down your node,
  • authentication,
  • load balances the traffic to multiple Oasis nodes.

This chapter will show you how to set up a public gRPC endpoint using Envoy so that it exposes only a safe subset of the Oasis RPC services. The final section presents an alternative approach to communicate with your node by securely tunnelling the Unix socket over the network, so it can safely be used by the client, but does not filter out any services.

Never expose the UNIX socket directly!

The oasis-node deliberately exposes the RPC interface only via an AF_LOCAL socket called internal.sock located in the node's data directory. This socket should never be directly exposed over the network as it has no authentication and allows full control—including shutting down your node.

gRPC Proxy with Envoy​

Let's set up a typical public Oasis endpoint using the Envoy HTTP proxy with the following behavior:

  • whitelisted methods for checking the network status, performing queries and submitting transactions,
  • no control methods allowed and no queries that are CPU or I/O intensive,
  • lives on grpc.example.com with TLS-enabled connection and certificates that you already have from Let's Encrypt,
  • internal.sock of the Oasis node is accessible at /node/data/internal.sock.
Example hostnames

This chapter uses various hostnames under the example.com domain. These only serve as an example and in a real deployment you should replace them with your own domain.

Envoy already has built-in support for gRPC so after installing Envoy, simply put the configuration below inside your envoy.yaml and then execute the proxy with envoy -c envoy.yaml.

envoy.yaml
# Envoy gRPC-web proxy configuration
---
admin:
  address:
    socket_address:
      address: "127.0.0.1"
      port_value: 10000
static_resources:
  listeners:
    - name: listener_0
      address:
        socket_address:
          address: "0.0.0.0"
          port_value: 443
      filter_chains:
        - filters:
            - name: envoy.filters.network.http_connection_manager
              typed_config:
                "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
                codec_type: AUTO
                stat_prefix: ingress_http
                access_log:
                  - name: envoy.file_access_log
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog
                      path: /dev/stdout
                route_config:
                  virtual_hosts:
                    - name: vh_0
                      domains:
                        - "*"
                      routes:
                        - match:
                            safe_regex:
                              regex: "\
/oasis-core\\.(\
  Beacon/(\
    ConsensusParameters|\
    GetBaseEpoch|\
    GetBeacon|\
    GetEpoch|\
    GetEpochBlock|\
    GetFutureEpoch)|\
  Consensus/(\
    EstimateGas|\
    GetBlock|\
    GetChainContext|\
    GetGenesisDocument|\
    GetNextBlockState|\
    GetParameters|\
    GetSignerNonce|\
    GetStatus|\
    GetTransactions|\
    GetTransactionsWithResults|\
    GetUnconfirmedTransactions|\
    MinGasPrice|\
    SubmitTx)|\
  Governance/(\
    ActiveProposals|\
    ConsensusParameters|\
    GetEvents|\
    PendingUpgrades|\
    Proposal|\
    Proposals|\
    Votes)|\
  NodeController/(\
    GetStatus)|\
  Registry/(\
    ConsensusParameters|\
    GetEntity|\
    GetEvents|\
    GetNode|\
    GetNodeByConsensusAddress|\
    GetNodeStatus|\
    GetRuntime|\
    GetRuntimes)|\
  RootHash/(\
    ConsensusParameters|\
    GetEvents|\
    GetGenesisBlock|\
    GetLastRoundResults|\
    GetLatestBlock|\
    GetRuntimeState)|\
  RuntimeClient/(\
    CheckTx|\
    GetBlock|\
    GetEvents|\
    GetGenesisBlock|\
    GetLastRetainedBlock|\
    GetTransactions|\
    GetTransactionsWithResults|\
    Query|\
    SubmitTx|\
    SubmitTxMeta|\
    SubmitTxNoWait|\
    WatchBlocks)|\
  Scheduler/(\
    ConsensusParameters|\
    GetCommittees|\
    GetValidators)|\
  Staking/(\
    Account|\
    Allowance|\
    CommonPool|\
    ConsensusParameters|\
    DebondingDelegationInfosFor|\
    DebondingDelegationsFor|\
    DebondingDelegationsTo|\
    DelegationInfosFor|\
    DelegationsFor|\
    DelegationsTo|\
    GetEvents|\
    GovernanceDeposits|\
    LastBlockFees|\
    Threshold|\
    TokenSymbol|\
    TokenValueExponent|\
    TotalSupply))\
"
                          route:
                            cluster: oasis_node_grpc
                            timeout: "0s"
                            max_stream_duration:
                              grpc_timeout_header_max: "0s"
                        - match:
                            prefix: /oasis-core
                          direct_response:
                            status: 404
                            body:
                              inline_string: Only some methods are allowed on this proxy.
                      typed_per_filter_config:
                        envoy.filters.http.cors:
                          "@type": type.googleapis.com/envoy.extensions.filters.http.cors.v3.CorsPolicy
                          expose_headers: grpc-status,grpc-message,grpc-status-details-bin
                          allow_origin_string_match:
                            - exact: '*'
                          allow_headers: content-type,x-grpc-web,x-user-agent
                          max_age: '1728000'
                http_filters:
                  - name: envoy.health_check
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.filters.http.health_check.v3.HealthCheck
                      pass_through_mode: false
                      headers:
                        - name: :path
                          string_match:
                            exact: /health
                  - name: envoy.filters.http.grpc_web
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.filters.http.grpc_web.v3.GrpcWeb
                  - name: envoy.filters.http.cors
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.filters.http.cors.v3.Cors
                  - name: envoy.filters.http.router
                    typed_config:
                      "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
          transport_socket:
            name: envoy.transport_sockets.tls
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.DownstreamTlsContext
              common_tls_context:
                alpn_protocols:
                  - h2,http/1.1
                tls_certificates:
                  - certificate_chain:
                      filename: /etc/letsencrypt/live/grpc.example.com/fullchain.pem
                    private_key:
                      filename: /etc/letsencrypt/live/grpc.example.com/privkey.pem
  clusters:
    - name: oasis_node_grpc
      connect_timeout: 0.25s
      load_assignment:
        cluster_name: cluster_0
        endpoints:
          - lb_endpoints:
              - endpoint:
                  address:
                    pipe:
                      path: /node/data/internal.sock
      typed_extension_protocol_options:
        envoy.extensions.upstreams.http.v3.HttpProtocolOptions:
          "@type": type.googleapis.com/envoy.extensions.upstreams.http.v3.HttpProtocolOptions
          explicit_http_config:
            http2_protocol_options: {}
layered_runtime:
  layers:
    - name: static
      static_layer:
        re2:
          max_program_size:
            error_level: 1000000

Tunnel Unix socket via SSH​

SSH supports forwarding a Unix socket over a secure layer. The command below will establish a secure shell to the example.com server and then tunnel the internal.sock file inside the data directory to a Unix socket inside your home folder:

ssh oasis@example.com -L /home/user/oasis-node-internal.sock:/node/data/internal.sock

The /home/user/oasis-node-internal.sock can now be used to safely connect to the Oasis node as if it was running locally without filtering any services. For example, using the Oasis CLI:

oasis network add-local my-oasis-node unix:/home/user/oasis-node-internal.sock
oasis network status --network my-oasis-node
Permanent SSH channel

To make a tunneled Unix socket over SSH permanent, consider using autossh.

See also​