popmd

Hemi PoP Miner (popmd)

popmd is the lightweight Hemi PoP (Proof-of-Proof) miner daemon.

The PoP Miner periodically receives information about the current state of the Hemi Network, in the form of a keystone. When a keystone is received, the PoP Miner creates a Bitcoin transaction containing the keystone data, and broadcasts the transaction to Bitcoin - tying the Hemi Network's state to Bitcoin.

PoP Mining on Hemi is incentivised with a reward algorithm, which pays out tokens for helping secure the Hemi Network by broadcasting network keystones.

System Requirements

The Hemi PoP Miner daemon (popmd) is extremely lightweight. It will run on almost any system, and requires minimal system resources.

By relying on connections to a Bitcoin node with indexed Hemi keystones (such as tbcd), and a hVM-aware op-geth node, popmd requires very minimal CPU and RAM to operate, as most heavy functionality is offloaded to these daemons.

[!TIP] Running a PoP Miner does not require a GPU or any specialised hardware. popmd can easily be run on a lightweight computer, such as a Raspberry Pi.

Running popmd

We support running popmd in Docker or as a standalone binary. We provide pre-built binaries, or you can build the popmd binary from source code.

[!IMPORTANT] Running a PoP Miner requires URLs for the following services:

• BTC Gozer with indexed keystones, such as tbcd.
• hVM-aware op-geth node

Standalone binary (Recommended)

Pre-built binaries for Linux, macOS, Windows, and OpenBSD are available via GitHub Releases.

After downloading and extracting the archive for your system, start popmd by running:

/path/to/popmd

[!NOTE] In production environments, especially when running PoP Miners on mainnet, we highly recommend verifying the checksum of the downloaded archive, as well as signatures provided for the archive, to ensure the security of your PoP Miner.

Docker (Recommended)

Docker images for popmd are published to both the GitHub Container Registry and Docker Hub.

Example

# Pull Hemi popmd image from Docker Hub
docker pull hemilabs/popmd

# Run the built image using the correct environment variables
docker run \
  -e POPM_BITCOIN_SECRET=<YOUR_BITCOIN_SECRET> \
  -e POPM_OPGETH_URL=<YOUR_OPGETH_URL> \
  -e POPM_BITCOIN_URL=<YOUR_BITCOIN_URL> \
  hemilabs/popmd:latest

[!NOTE] In production environments, especially when running PoP Miners on mainnet, we highly recommend verifying image signatures and pinning images to SHA-256 digests, to ensure the security of your PoP Miner.

Building Docker images

The heminetwork repository provides Docker files, which can be used to build Docker images locally.

Prerequisites

• docker CLI installed and setup.

Execution

To build the Docker image locally and run a popmd daemon, use the following:

[!IMPORTANT] Check the runtime settings section for a full list of available environment variables.

cd heminetwork

# Build the image using the popmd Dockerfile
docker build -t popmd:dev -f ./docker/popmd/Dockerfile .

# Run the built image using the correct environment variables
docker run \
  -e POPM_BITCOIN_SECRET=<YOUR_BITCOIN_SECRET> \
  -e POPM_OPGETH_URL=<YOUR_OPGETH_URL> \
  -e POPM_BITCOIN_URL=<YOUR_BITCOIN_URL> \
  popmd:dev

Building from Source

Prerequisites

• Go v1.24+
• make (optional)

Option 1: Using Makefile

If you have make installed on your system, you may build the binary by running the following code snippet:

cd heminetwork

# Download and install dependencies
make deps

# Output binary will be written to bin/popmd or bin/popmd.exe
make popmd

Option 2: Standalone Build

If you prefer not to use the Makefile:

cd heminetwork

# Build the binary (output will be popmd or popmd.exe)
go build ./cmd/popmd/

# Install the binary (output will be in your GOBIN directory)
go install ./cmd/popmd/

Once the popmd binary is built using one of the two options above, you can start it by running:

/path/to/popmd

Runtime Settings

popmd is designed to be run both locally and in cloud environments, as such it uses environment variables for runtime settings.

To see a full list of runtime settings, execute popmd with the --help flag:

./bin/popmd --h
# Hemi Proof-of-Proof Miner v2.0.0-dev+76217560a (popmd, go1.24.5 linux/amd64)
# Usage:
#         help (this help)
# Environment:
#         POPM_BITCOIN_NETWORK   : bitcoin chain to connect to (ex. "mainnet", "testnet3|testnet4") (default: mainnet)
#         POPM_BITCOIN_SECRET    : bitcoin secret (mnemonic, seed, xpriv) (required) 
#         POPM_BITCOIN_URL       : tbc bitcoin url to connect to (default: ws://localhost:8082/v1/ws)
#         POPM_LOG_LEVEL         : loglevel for various packages; INFO, DEBUG and TRACE (default: popmd=INFO;popm=INFO)
#         POPM_OPGETH_URL        : URL for opgeth (default: localhost:9999)
#         POPM_PPROF_ADDRESS     : address and port popm pprof listens on (open <address>/debug/pprof to see available profiles) 
#         POPM_PROMETHEUS_ADDRESS: address and port popm prometheus listens on 
#         POPM_REMINE_THRESHOLD  : the number of L2 Keystones behind the latest seen that we are willing to remine, this is handy for re-orgs (default: 0)
#         POPM_STATIC_FEE        : static fee amount in sats/byte; overrides fee estimation if greater than 0. Can be decimal (ex. 1.5 sats/byte) (default: 0)

Namely, ensure the following variables are properly set:

[!CAUTION] Running a PoP Miner requires providing a private key for a funded Bitcoin wallet. It is important to keep this private key safe and secure, to prevent loss of funds.

It is recommended to create a new wallet specifically for use by the PoP Miner, and not to reuse existing wallets.

• POPM_BITCOIN_NETWORK: This determines what Bitcoin network popmd should connect to. This defaults to mainnet, however testnet3, testnet4 and localnet are also available for test environments.

• POPM_BITCOIN_SECRET: A funded Bitcoin address is necessary in order to sign, broadcast, and get rewarded for the transactions constructed by popmd. The private key for the funded wallet must be provided here.

• POPM_BITCOIN_URL*: URL to the Bitcoin node used in order to transmit data to and from the Bitcoin network. Read more on how to run your own tbcd instance here.

• POPM_OPGETH_URL: URL to an accessible hVM-aware op-geth instance, used to retrieve keystones from the Hemi Network.

[!NOTE] * TBC is currently the only functional Bitcoin node providing indexed Hemi keystones.

FAQ

How much does it cost to run popmd?

Hemi L2 Blocks are generated approximately every 12 seconds, and a keystone is generated every 25 blocks. As such:

• 12 * 25 = 300 seconds (5 minutes) between keystones
• 86400 / 300 = 288 keystones per day

Considering that each transaction created by the PoP Miner has a size of 284 vB and presuming an average bitcoin transaction fee of 3 sats/vB:

• 284 * 3 = 852 sats per PoP transaction
• 852 * 288 = 245376 sats or 0.00245376 BTC per day

The value of BTC can fluctuate heavily, but presuming a cost of 110,000 USD / BTC, it would cost ~270 USD per day to run popmd on mainnet - assuming the PoP Miner broadcasts a transaction for every generated Hemi keystone.

[!WARNING] These are example values ONLY. The presented values are not guaranteed, and may not be up-to-date. Different versions of the network's protocols and daemons may incur higher costs and fees. You should get up-to-date values yourself to determine if PoP mining makes sense for you.

How many HEMI tokens will I be awarded for mining?

Last updated: August 2025

With the current PoP payout algorithm, each keystone has a total payout of 100 HEMI, which is divided by the number of PoP transactions that mine said keystone.

On average, a new keystone is created every 5 minutes, meaning 28,800 HEMI is paid out to PoP miners per day.

The total payout is divided between the PoP Miners which broadcast a transaction for a keystone, meaning that the total payout a single PoP Miner will receive is heavily dependent on the number of PoP Miners actively broadcasting.

[!WARNING] These values are not guaranteed, and may not be up-to-date. Different versions of the network's protocols and daemons may incur higher costs or fees. You should get up-to-date values yourself to determine if PoP mining makes sense for you.