== Upstreams Configuration

Dshackle can connect to multiple independent APIs ("upstreams") and provides an unified API on top of it.

Supported upstream protocols:

- JSON RPC
- Websockets
- gRPC (i.e. can connect to another Dshackle)

Those protocols can be configures with additional security, TLS and authentication.

=== Example

.upstreams.yaml
[source,yaml]
----
version: v1

defaults:
  - chains:
      - ethereum
    options:
      min-peers: 10
  - chains:
      - kovan
    options:
      min-peers: 2

upstreams:
  - id: us-nodes
    chain: auto
    connection:
      grpc:
        host: 35.226.252.117
        port: 443
        tls:
          ca: ca.crt
          certificate: client.crt
          key: client.p8.key
  - id: infura-eth
    chain: ethereum
    labels:
      provider: infura
    options:
      disable-validation: true
    connection:
      ethereum:
        rpc:
          url: "https://mainnet.infura.io/v3/${INFURA_USER}"
          basic-auth:
            username: ${INFURA_USER}
            password: ${INFURA_PASSWD}
        ws:
          url: "wss://mainnet.infura.io/ws/v3/${INFURA_USER}"
          basic-auth:
            username: ${INFURA_USER}
            password: ${INFURA_PASSWD}
----

There're two main segments for upstreams configuration:

- _upstreams_ - a list of API to connect to, with all configuration specific for upstream and chain
- and _default options_ as common configuration options applied to all nodes in that group

In the example above we have:

- default configuration for _Ethereum Mainnet_ which accepts upstream as valid when it not in fast synchronization mode
  and has at least 10 peers. For _Kovan Testnet_ nodes the requirements are much relieved
- as upstreams it has 2 configurations
  * balancer connects to another Dshackle/another machine by using gRPC protocol
    ** accepts (i.e. proxies) any blockchain available on that remote
    ** verifies TLS certificate of the server
    ** uses client certificate for authentication, i.e. remote server is accepting only clients authenticated by a
       certificate
  * connects to Infura provided _Ethereum Mainnet_
    ** configuration is using placeholders for `${INFURA_USER}` and `${INFURA_PASSWD}` which will be replaced with
       corresponding environment variables values
    ** uses Basic Authentication to authenticate requests on Infura
    ** label `[provider: infura]` is set for that particular upstream, which can be selected during a request. For example for
      some requests you may want to use nodes with that label only, i.e. _"send that tx to infura nodes only"_,
      or _"read only from archive node, with label [archive: true]"_
    ** upstream validation (peers, sync status, etc) is disabled for that particular upstream

=== Configuration options

Options (default or as part of upstream config):

[cols="2,1,5a"]
|===
| Option | Default | Description

| `disable-validation` | false | if `true` then Dshackle will not try to verify status of the upstream (could be useful for a trusted cloud
   provider such as Infura, but disabling it is not recommended for a normal node)
| `min-peers` | 3 | specify minimum amount of connected peers, Dshackle will not use upstream with less than specified number
| `timeout` | 60 | timeout in seconds after which request to the upstream will be discarded (and may be retried on an another upstream)
|===

=== Connection type

Dshackle currently supports

- `rpc` a standard Ethereum JSON RPC
- `ws` websocket connection (supposed to be used in addition to `rpc` connection)
- `grpc` connects to another Dshackle instance

=== Methods

.By default an ethereum upstream supports following JSON RPC methods:
- `eth_gasPrice`
- `eth_call`
- `eth_estimateGas`
- `eth_getBlockTransactionCountByHash`
- `eth_getUncleCountByBlockHash`
- `eth_getBlockByHash`
- `eth_getTransactionByHash`
- `eth_getTransactionByBlockHashAndIndex`
- `eth_getStorageAt`
- `eth_getCode`
- `eth_getUncleByBlockHashAndIndex`
- `eth_getTransactionCount`
- `eth_blockNumber`
- `eth_getBalance`
- `eth_sendRawTransaction`
- `eth_getBlockTransactionCountByNumber`
- `eth_getUncleCountByBlockNumber`
- `eth_getBlockByNumber`
- `eth_getTransactionByBlockNumberAndIndex`
- `eth_getTransactionReceipt`
- `eth_getUncleByBlockNumberAndIndex`


.Plus following methods are answered directly by Dshackle
- `net_version`
- `net_peerCount`
- `net_listening`
- `web3_clientVersion`
- `eth_protocolVersion`
- `eth_syncing`
- `eth_coinbase`
- `eth_mining`
- `eth_hashrate`
- `eth_accounts`

It's possible to enable additional methods that are available on upstream, or disable an existing method. For that purpose
there is `methods` configuration:

[source, yaml]
----
upstreams:
  - id: my-node
    chain: ethereum
    labels:
      archive: true
    methods:
      enabled:
        - name: trace_transaction
      disabled:
        - name: eth_getBlockByNumber
----

Such configuration option allows to execute method `trace_transaction` and also disables `eth_getBlockByNumber` on that
particular upstream. If a client requests to execute method `trace_transaction` then it will be scheduled to that upstream (or
any upstream with such method enabled).

NOTE: It's especially useful when used together with upstream labels. If an archive upstream has label `archive: true` it's
possible to specify that the client wants to execute method `trace_transaction` only on an archive node(s), which has
complete historical data for tracing.

=== Authentication

==== TLS

All connection types can use TLS secured connection, with optional client certificate authentication:

- `ca` path to certificate required from remote server
- optional `certificate` and `key` for client authentication.

NOTE: Please note that `key` must be encoded with _PKCS 8_

==== Basic Authentication

For JSON RPC and Websockets a Basic Authentication can be used:

- `username` - username
- `password` - password