dcrd

Decred Overview

Decred is a blockchain-based cryptocurrency with a strong focus on community input, open governance, and sustainable funding for development. It utilizes a hybrid proof-of-work and proof-of-stake mining system to ensure that a small group cannot dominate the flow of transactions or make changes to Decred without the input of the community. A unit of the currency is called a decred (DCR).

https://decred.org

Latest Downloads

https://decred.org/downloads

What is dcrd?

dcrd is a full node implementation of Decred written in Go (golang).

It acts as a fully-validating chain daemon for the Decred cryptocurrency. dcrd maintains the entire past transactional ledger of Decred and allows relaying of transactions to other Decred nodes around the world.

This software is currently under active development. It is extremely stable and has been in production use since February 2016.

The software was originally forked from btcd, which is a bitcoin full node implementation that is still under active development. To gain the benefit of btcd's ongoing upgrades, including improved peer and connection handling, database optimization, and other blockchain related technology improvements, dcrd is continuously synced with the btcd codebase.

What is a full node?

The term 'full node' is short for 'fully-validating node' and refers to software that fully validates all transactions and blocks, as opposed to trusting a 3rd party. In addition to validating transactions and blocks, nearly all full nodes also participate in relaying transactions and blocks to other full nodes around the world, thus forming the peer-to-peer network that is the backbone of the Decred cryptocurrency.

The full node distinction is important, since full nodes are not the only type of software participating in the Decred peer network. For instance, there are 'lightweight nodes' which rely on full nodes to serve the transactions, blocks, and cryptographic proofs they require to function, as well as relay their transactions to the rest of the global network.

Why run dcrd?

As described in the previous section, the Decred cryptocurrency relies on having a peer-to-peer network of nodes that fully validate all transactions and blocks and then relay them to other full nodes.

Running a full node with dcrd contributes to the overall security of the network, increases the available paths for transactions and blocks to relay, and helps ensure there are an adequate number of nodes available to serve lightweight clients, such as Simplified Payment Verification (SPV) wallets.

Without enough full nodes, the network could be unable to expediently serve users of lightweight clients which could force them to have to rely on centralized services that significantly reduce privacy and are vulnerable to censorship.

In terms of individual benefits, since dcrd fully validates every block and transaction, it provides the highest security and privacy possible when used in conjunction with a wallet that also supports directly connecting to it in full validation mode, such as dcrwallet (CLI) and Decrediton (GUI).

Minimum Recommended Specifications (dcrd only)

• 10 GB disk space (as of September 2018, increases over time)
• 1GB memory (RAM)
• ~150MB/day download, ~1.5GB/day upload
  • Plus one-time initial download of the entire block chain
• Windows 7/8.x/10 (server preferred), macOS, Linux
• High uptime

Getting Started

So, you've decided to help the network by running a full node. Great! Running dcrd is simple. All you need to do is install dcrd on a machine that is connected to the internet and meets the minimum recommended specifications, and launch it.

Also, make sure your firewall is configured to allow inbound connections to port 9108.

Installing and updating

Binaries (Windows/Linux/macOS)

Binary releases are provided for common operating systems and architectures:

https://decred.org/downloads

Build from source (all platforms)

Building or updating from source requires the following build dependencies:

• Go 1.11 or 1.12

  Installation instructions can be found here: https://golang.org/doc/install. It is recommended to add $GOPATH/bin to your PATH at this point.

• Git

  Installation instructions can be found at https://git-scm.com or https://gitforwindows.org.

To build and install from a checked-out repo, run go install . ./cmd/... in the repo's root directory. Some notes:

• Set the GO111MODULE=on environment variable if building from within GOPATH.

• The dcrd executable will be installed to $GOPATH/bin. GOPATH defaults to $HOME/go (or %USERPROFILE%\go on Windows) if unset.

Example of obtaining and building from source on Windows 10:

PS> git clone https://github.com/decred/dcrd $env:USERPROFILE\src\dcrd
PS> cd $env:USERPROFILE\src\dcrd
PS> go install . .\cmd\...
PS> & "$(go env GOPATH)\bin\dcrd" -V

Docker

Running dcrd

You can run a decred node from inside a docker container. To build the image yourself, use the following command:

docker build -t decred/dcrd .

Or you can create an alpine based image (requires Docker 17.05 or higher):

docker build -t decred/dcrd:alpine -f Dockerfile.alpine .

You can then run the image using:

docker run decred/dcrd

You may wish to use an external volume to customise your config and persist the data in an external volume:

docker run --rm -v /home/user/dcrdata:/root/.dcrd/data decred/dcrd

For a minimal image, you can use the decred/dcrd:alpine tag. This is typically a more secure option while also being a much smaller image.

You can run dcrctl from inside the image. For example, run an image (mounting your data from externally) with:

docker run --rm -ti --name=dcrd-1 -v /home/user/.dcrd:/root/.dcrd \
  decred/dcrd:alpine

And then run dcrctl commands against it. For example:

docker exec -ti dcrd-1 dcrctl getbestblock

Running Tests

All tests and linters may be run in a docker (or podman) container using the script run_tests.sh by specifying either docker or podman as the first parameter. This script defaults to using the current latest supported version of Go, but it also respects the GOVERSION environment variable set to the major version of Go to allow testing on a previous version of Go. Generally, Decred only supports the current and previous major versions of Go.

./run_tests.sh docker

To run the tests locally without docker on the latest supported version of Go:

./run_tests.sh

To run the tests locally without docker on Go 1.11:

GOVERSION=1.11 ./run_tests.sh

Contact

If you have any further questions you can find us at:

https://decred.org/community

Issue Tracker

The integrated github issue tracker is used for this project.

Documentation

The documentation for dcrd is a work-in-progress. It is located in the docs folder.

License

dcrd is licensed under the copyfree ISC License.