Setting Up a Consensus Follower

A full observer node follows the Flow protocol consensus to track new finalized blocks, which is accomplished using the consensus follower library included in github.com/onflow/flow-go/follower. This repo provides a working example of how to use the consensus follower library.

There are other features that make up a full observer node, namely, tracking Flow execution state. For an example of a complete full observer node, see DPS.

Fetching genesis data

Download snapshot data

For testnet

mkdir -p bootstrap/public-root-information
wget -P bootstrap/public-root-information https://storage.googleapis.com/flow-genesis-bootstrap/full_observer_bootstrap/root-protocol-state-snapshot.json
wget -P bootstrap/public-root-information https://storage.googleapis.com/flow-genesis-bootstrap/full_observer_bootstrap/root-protocol-state-snapshot.json.asc

For mainnet

mkdir -p bootstrap/public-root-information
wget -P bootstrap/public-root-information https://storage.googleapis.com/flow-genesis-bootstrap/full_observer_bootstrap_mainnet/root-protocol-state-snapshot.json
wget -P bootstrap/public-root-information https://storage.googleapis.com/flow-genesis-bootstrap/full_observer_bootstrap_mainnet/root-protocol-state-snapshot.json.asc

Verify the PGP signature

If this is the first time going through this process, add the [email protected] public key.

gpg --keyserver keys.openpgp.org --search-keys [email protected]

Verify the snapshot file

gpg --verify bootstrap/public-root-information/root-protocol-state-snapshot.json.asc

gpg: assuming signed data in 'bootstrap/public-root-information/root-protocol-state-snapshot.json'
gpg: Signature made Wed Sep 15 11:34:33 2021 PDT
gpg:                using ECDSA key 40CD95717AC463E61EE3B285B718CA310EDB542F
gpg: Good signature from "Flow Team (Flow Full Observer node snapshot verification master key) <[email protected]>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 7D23 8D1A E6D3 2A71 8ECD  8611 CB52 64F7 FD4C DD27
     Subkey fingerprint: 40CD 9571 7AC4 63E6 1EE3  B285 B718 CA31 0EDB 542F

Staked Access Nodes

Below are access nodes that support connections from observer nodes for each network.

Note: while the public keys remain the same, the hostnames change each spork to include the spork name. Substitute [devnet_spork] and [mainnet_spork] with the appropriate spork name (e.g. mainnet14). See Past Sporks for the current spork for each network.

For testnet

Access-003:

• Host: access-003.[devnet_spork].nodes.onflow.org
• Public Key: b662102f4184fc1caeb2933cf87bba75cdd37758926584c0ce8a90549bb12ee0f9115111bbbb6acc2b889461208533369a91e8321eaf6bcb871a788ddd6bfbf7

Access-004:

• Host: access-004.[devnet_spork].nodes.onflow.org
• Public Key: 0d1523612be854638b985fc658740fa55f009f3cd49b739961ab082dc91b178ed781ef5f66878613b4d34672039150abfd9c8cfdfe48c565bca053fa4db30bec

For mainnet

Access-007:

• Host: access-007.[mainnet_spork].nodes.onflow.org
• Public Key: 28a0d9edd0de3f15866dfe4aea1560c4504fe313fc6ca3f63a63e4f98d0e295144692a58ebe7f7894349198613f65b2d960abf99ec2625e247b1c78ba5bf2eae

Access-008:

• Host: access-008.[mainnet_spork].nodes.onflow.org
• Public Key: 11742552d21ac93da37ccda09661792977e2ca548a3b26d05f22a51ae1d99b9b75c8a9b3b40b38206b38951e98e4d145f0010f8942fd82ddf0fb1d670202264a

Launching your node

Build

The consensus follower requires the crypto modules from onflow/flow-go, which must be built locally.

Clone the flow-go repo

git clone https://github.com/onflow/flow-go.git

Follow the instructions in the flow-go README up to make install-tools.

Once crypto has been installed, build the observer node.

go build -o observer --tags relic main.go

Launch

The following are examples of how to launch observer nodes following staked Access Nodes in different networks.

For testnet

Launch the observer node following access-003.devnet30.nodes.onflow.org on testnet

mkdir /tmp/data

export DEVNET_SPORK=devnet30
export ACCESS_NODE_HOSTNAME=access-003.${DEVNET_SPORK}.nodes.onflow.org
export ACCESS_NODE_NETWORKING_PUBLIC_KEY=b662102f4184fc1caeb2933cf87bba75cdd37758926584c0ce8a90549bb12ee0f9115111bbbb6acc2b889461208533369a91e8321eaf6bcb871a788ddd6bfbf7
./observer

For mainnet

Launch the observer node following access-008.mainnet14.nodes.onflow.org on mainnet

mkdir /tmp/data

export MAINNET_SPORK=mainnet14
export ACCESS_NODE_HOSTNAME=access-008.${MAINNET_SPORK}.nodes.onflow.org
export ACCESS_NODE_NETWORKING_PUBLIC_KEY=11742552d21ac93da37ccda09661792977e2ca548a3b26d05f22a51ae1d99b9b75c8a9b3b40b38206b38951e98e4d145f0010f8942fd82ddf0fb1d670202264a
./observer