Run a Fibre server

Fibre is a separate data availability service operated by validators alongside celestia-app. This guide covers Mocha using the celestia-app release v10.2.0-mocha and its matching Fibre binary.

Prerequisites

• A running, synced validator node in the bonded validator set. Fibre derives its storage budget from your stake.
• The v10 multiplexer celestia-app binary installed before activation. Follow the Mocha release upgrade instructions  and check the celestia-app installation requirements.
• Separate disks for Fibre data and celestia-app data. Review the connection limits and memory requirements.
• If using an external key management system, support for SignRawBytes and median signing latency no higher than 10 ms. Fibre connects to the node’s signing service, not directly to the KMS.

Install Fibre

Prebuilt binary

Download the Fibre archive and checksums from the same release as celestia-app. For Linux x86_64:

fibre_version=v10.2.0-mocha
curl -fLO "https://github.com/celestiaorg/celestia-app/releases/download/$fibre_version/fibre_Linux_x86_64.tar.gz"
curl -fLO "https://github.com/celestiaorg/celestia-app/releases/download/$fibre_version/checksums.txt"
sha256sum --ignore-missing --check checksums.txt
tar -xzf fibre_Linux_x86_64.tar.gz
./fibre version

For Linux arm64, use fibre_Linux_arm64.tar.gz. macOS archives use Darwin instead of Linux; verify them with shasum -a 256 --ignore-missing --check checksums.txt. Place the verified binary on your executable path before using fibre below.

Build from source

Install Git, Make, a C compiler, and the Go version required by the release’s go.mod. Clone the same release used by your celestia-app node:

git clone --branch v10.2.0-mocha --depth 1 https://github.com/celestiaorg/celestia-app.git celestia-app-fibre
cd celestia-app-fibre
make build-fibre-server VERSION=v10.2.0-mocha
./build/fibre version

The binary is written to build/fibre with the release version and short commit hash. Setting VERSION avoids selecting another network’s tag when tags share a commit. Place the binary on your executable path before using fibre below.

Configure the node connections

Fibre needs the application’s gRPC service and the validator’s signing service.

Paths are relative to your existing node home, normally ~/.celestia-app. Back up the configuration files before editing. Edit existing keys and sections instead of appending duplicate TOML sections.

Enable application gRPC

In config/app.toml, edit the existing [grpc] section:

[grpc]
enable = true
address = "127.0.0.1:9090"

Enable it explicitly: a freshly generated app config disables application gRPC, even though the multiplexer enables it for its embedded v9 application. The setting must also be enabled when the chain switches to v10.

The core RPC gRPC listener ([rpc] grpc_laddr in config/config.toml) is a separate service. Keep its existing address for bridge nodes and other clients; Fibre’s --app-grpc-address must point to the application service above.

Configure the signing connection

In config/config.toml, edit the top-level setting before the first section:

priv_validator_grpc_laddr = "127.0.0.1:26669"

Fresh v10 configs use 26669 to avoid a TMKMS port clash. Existing configs may still use 26659, a custom address, or an empty value that disables the service. Replacing the binary does not rewrite the saved value. If you change the port, change Fibre’s signer address to match. A working custom port can be retained when it does not conflict with another listener.

Application and signing addresses, including Fibre’s connection options, use host:port without tcp://.

Restart the node after editing and confirm it resumes syncing and signing. Check service-manager flags for overrides. If deployment tooling manages the configuration, update its source templates too.

Transport security (TLS)

Fibre encrypts all client connections with TLS. You do not need to obtain or renew certificates. At startup, the server generates a certificate and asks the node’s signing service to endorse it with your validator’s consensus key. Clients check that endorsement against the validator set.

The certificate identifies the validator by its consensus key, so the registered host can be an IP address or a DNS name. Each restart generates a new certificate. Restart Fibre after changing --signer-grpc-address so it uses the correct key.

Downloads are public; any peer can read shards. Uploads require a valid payment promise. There is no plaintext fallback: all Fibre servers and clients must use a TLS-capable build. The application and signing connections remain unencrypted, so keep them on loopback or a trusted private network.

Start after activation

Check the active app version through your node’s HTTP RPC endpoint:

curl -s http://127.0.0.1:26657/abci_info

Confirm result.response.app_version is 10 or later. Checking the installed binary’s version alone is insufficient.

Start Fibre with its data home on the separate disk:

fibre start \
  --home <fibre_home> \
  --app-grpc-address 127.0.0.1:9090 \
  --signer-grpc-address 127.0.0.1:26669 \
  --server-listen-address 0.0.0.0:7980

Use your actual node addresses if different. On first start, Fibre creates server_config.toml under its home. The corresponding keys are app_grpc_address, signer_grpc_address, and server_listen_address; command-line flags override the file. Check the startup log for the chain ID and connected addresses.

Connection limits and memory

Set connection limits in <fibre_home>/server_config.toml. These are the defaults:

max_connections = 16
max_concurrent_streams = 13

max_connections limits client connections to the server. max_concurrent_streams limits concurrent gRPC streams per connection. Each in-flight upload stream can buffer a full message of about 132 MiB:

worst-case receive buffers ≈ max_connections × max_concurrent_streams × 132 MiB

The defaults allow about 27 GiB of receive buffers. Leave additional RAM for celestia-app, Fibre’s other work, and the operating system. Increase the limits only when the host has enough memory.

Upload traffic can fill all 16 connection slots and block concurrent downloads. To leave slots for downloads, raise max_connections above 16 and check the memory budget again. Add either setting if it is absent from an existing config, then restart Fibre for changes to take effect.

Register the public address

Once Fibre is running and reachable, register its public host using your validator account:

celestia-appd tx valaddr set-host <public_host>:7980 \
  --from <validator_account_key> --chain-id mocha-5
celestia-appd query valaddr providers

Add your usual node, home, and transaction fee flags. The host must be host:port, without a URL scheme. Confirm your address appears in the provider list. Register only after the server is reachable, so clients do not discover an unavailable host. Registration requires active app version 10 and a bonded validator.

Troubleshoot startup

For logging, metrics, tracing, and profiling, see Fibre metrics and monitoring. The Fibre server reference  has further configuration details.