DevOps Take Home Task

The beginning of this README file explains the steps taken to complete the home assignment, afterwards, there is the official documentation of the golang execution layer implementation for the Ethereum protocol.

I'll describe my actions step by step as per the assignment:

1. Fork the following repo:

   • go-ethereum (geth) https://github.com/ethereum/go-ethereum
     • If you are reading this then you are in the right place, a fork of the source :)

2. Update your forked repo with the following functionality:

   • When a PR with label CI:Build is merged in it, a trigger kicks in and:

   • builds a new docker image of the given project

   • uploads it to a registry

     • This workflow is realized with the .github/workflows/docker-image.yml file, once opened you will see that I've written comments to give a more detailed explanation for each of the steps.

   • Create a Docker Compose definition that runs a local devnet with the newly built image.

     • The Docker compose file resides in the /docker-compose folder in the git repository named: docker-compose.yaml, again I've added comments for the steps for further details. An issue I encountered with the docker compose file is I could not pull dynamically tagged images built with the CI:Build workflow (described also as a comment in the docker-image.yml workflow) so I reverted to using :latest tag.

3. Create e new directory named hardhat in the repository. Inside it start a new Sample Hardhat Project (following official Hardhat docs).

• 'https://hardhat.org/hardhat-runner/docs/getting-started#overview' was followed to initialize a Javascript project in the folder hardhat. The .gitignore file was also created during the sample project deployment.

  • When a PR with label CI:Deploy is merged in the repo, a pipeline is triggered that:
  • runs a local devnet using the forked go-ethereum image.
  • deploys the Sample Hardhat Project to it.
  • builds a new docker image, which allows to run an instance of the devnet with the contracts already deployed and uploads it to the same registry with a suitable different tag

• These four steps were realized with the .github/workflows/deploy-hardhat.yml file, I've also commented within the file to explain the steps I've taken to realize the goal of the task.

4. Add a step to the pipeline which runs the hardhat tests from the sample project against the image with predeployed contracts.

   • This is also realized in the .github/workflows/deploy-hardhat.yml
   • I've commented before the step which checks the contracts to give details.

5. Create a Terraform script that quickly creates a k8s cluster in the cloud and deploys an instance of the built image to it.

   • The terraform script I've written resides inside the terraform folder in the root of the repository. For the purpose of this task, I used GCP and its GKE service. Initially, I followed official documentation from Google on deploying a sample application with terraform, having multiple .tf files, however, it turned out way heavier and complicated than expected so I started simplifying until I had the single main.tf file with all the providers and resources inside of it so that I can complete the goal of the task with least overhead, afterwards, upgrade and deployment of additional services is always possible.
   • Comments for each of the different components in the terraform script are added to explain further what I'm doing to accomplish the task.
   • The cluster is operational and running, the following screenshots are illustrating how the cluster is viewed through the Google cloud console and screenshots of running a hardhat test against one of the running pods with our image built from previous steps.
   • A view of the k8s cluster running in GCP
   • 
   • A view of all nodes running
   • 
   • A view of testing hardhat contracts to one of the running pods of the image we built
   • 

6. (Bonus) Add Blockscout Explorer to the Docker Compose definition created

   • For the purpose of this task I reviewed the documentation inside: https://docs.blockscout.com/for-developers/deployment/docker-compose-deployment and as well as in the https://github.com/blockscout/blockscout/tree/master/docker-compose for further details

   • I've updated the docker-compose.yml file in the docker-compose folder.

   • Initially, I was searching for an already pre-built docker image but there isn't just one published in a registry, however, after further look through I noticed that each of the services described in the geth.yml file points to its needed docker image, and each of the services has its own docker compose file described in the docker-compose/services folder which I cloned over from the Blockscout github repository. This still ensures that the pulling of the image is dynamic as it will get the latest available image when run.

   • The files that are not dynamically updated are the environment configurations in the envs folder and the proxy configurations in the proxy folder.

   • When initially built the docker-compose file creates several other directories needed to store data, I've added all of those to the .gitignore file so that they are not uploaded to the github repository.

   • When the docker-compose file is spun up locally all of the services and containers start up successfully and the services built by Blockscout Explorer are able to communicate with the go-ethereum image built in point 1 of this assignment.

   • 

   • The only issue I'm encountering is that I can't get the frontend to show up. In the documentation, its described that if the node is ran locally it should be on HTTP://0.0.0.0 rather than HTTP://127.0.0.1 but even after I alter the configuration I'm unable to display the front end.

   • I was unable to find what exactly was causing this issue and could not see an error that could point me to where this issue might be. I'll investigate further locally.

Usage of AI

• For this assignment, I utilized AI assistance only when encountering specific errors or issues, for some cases I found it easier to explain how I reached an error to AI than to spend a lot of time searching for similar issues. Of course, AI only pointed me to what I should be looking into rather than doing the task instead of me, furthermore, since AI does not have entirely up-to-date information I could not utilize it much, I even resorted to searching for some solutions in the Blockscout Explorer discord channel :)

Go Ethereum

Golang execution layer implementation of the Ethereum protocol.

Automated builds are available for stable releases and the unstable master branch. Binary archives are published at https://geth.ethereum.org/downloads/.

Building the source

For prerequisites and detailed build instructions please read the Installation Instructions.

Building geth requires both a Go (version 1.21 or later) and a C compiler. You can install them using your favourite package manager. Once the dependencies are installed, run

make geth

or, to build the full suite of utilities:

make all

Executables

The go-ethereum project comes with several wrappers/executables found in the cmd directory.

Command	Description
geth	Our main Ethereum CLI client. It is the entry point into the Ethereum network (main-, test- or private net), capable of running as a full node (default), archive node (retaining all historical state) or a light node (retrieving data live). It can be used by other processes as a gateway into the Ethereum network via JSON RPC endpoints exposed on top of HTTP, WebSocket and/or IPC transports. geth --help and the CLI page for command line options.
clef	Stand-alone signing tool, which can be used as a backend signer for geth.
devp2p	Utilities to interact with nodes on the networking layer, without running a full blockchain.
abigen	Source code generator to convert Ethereum contract definitions into easy-to-use, compile-time type-safe Go packages. It operates on plain Ethereum contract ABIs with expanded functionality if the contract bytecode is also available. However, it also accepts Solidity source files, making development much more streamlined. Please see our Native DApps page for details.
bootnode	Stripped down version of our Ethereum client implementation that only takes part in the network node discovery protocol, but does not run any of the higher level application protocols. It can be used as a lightweight bootstrap node to aid in finding peers in private networks.
evm	Developer utility version of the EVM (Ethereum Virtual Machine) that is capable of running bytecode snippets within a configurable environment and execution mode. Its purpose is to allow isolated, fine-grained debugging of EVM opcodes (e.g. evm --code 60ff60ff --debug run).
rlpdump	Developer utility tool to convert binary RLP (Recursive Length Prefix) dumps (data encoding used by the Ethereum protocol both network as well as consensus wise) to user-friendlier hierarchical representation (e.g. rlpdump --hex CE0183FFFFFFC4C304050583616263).

Running geth

Going through all the possible command line flags is out of scope here (please consult our CLI Wiki page), but we've enumerated a few common parameter combos to get you up to speed quickly on how you can run your own geth instance.

Hardware Requirements

Minimum:

• CPU with 2+ cores
• 4GB RAM
• 1TB free storage space to sync the Mainnet
• 8 MBit/sec download Internet service

Recommended:

• Fast CPU with 4+ cores
• 16GB+ RAM
• High-performance SSD with at least 1TB of free space
• 25+ MBit/sec download Internet service

Full node on the main Ethereum network

By far the most common scenario is people wanting to simply interact with the Ethereum network: create accounts; transfer funds; deploy and interact with contracts. For this particular use case, the user doesn't care about years-old historical data, so we can sync quickly to the current state of the network. To do so:

$ geth console

This command will:

• Start geth in snap sync mode (default, can be changed with the --syncmode flag), causing it to download more data in exchange for avoiding processing the entire history of the Ethereum network, which is very CPU intensive.
• Start the built-in interactive JavaScript console, (via the trailing console subcommand) through which you can interact using web3 methods (note: the web3 version bundled within geth is very old, and not up to date with official docs), as well as geth's own management APIs. This tool is optional and if you leave it out you can always attach it to an already running geth instance with geth attach.

A Full node on the Görli test network

Transitioning towards developers, if you'd like to play around with creating Ethereum contracts, you almost certainly would like to do that without any real money involved until you get the hang of the entire system. In other words, instead of attaching to the main network, you want to join the test network with your node, which is fully equivalent to the main network, but with play-Ether only.

$ geth --goerli console

The console subcommand has the same meaning as above and is equally useful on the testnet too.

Specifying the --goerli flag, however, will reconfigure your geth instance a bit:

• Instead of connecting to the main Ethereum network, the client will connect to the Görli test network, which uses different P2P bootnodes, different network IDs and genesis states.
• Instead of using the default data directory (~/.ethereum on Linux for example), geth will nest itself one level deeper into a goerli subfolder (~/.ethereum/goerli on Linux). Note, on OSX and Linux this also means that attaching to a running testnet node requires the use of a custom endpoint since geth attach will try to attach to a production node endpoint by default, e.g., geth attach <datadir>/goerli/geth.ipc. Windows users are not affected by this.

Note: Although some internal protective measures prevent transactions from crossing over between the main network and test network, you should always use separate accounts for play and real money. Unless you manually move accounts, geth will by default correctly separate the two networks and will not make any accounts available between them.

Configuration

As an alternative to passing the numerous flags to the geth binary, you can also pass a configuration file via:

$ geth --config /path/to/your_config.toml

To get an idea of how the file should look like you can use the dumpconfig subcommand to export your existing configuration:

$ geth --your-favourite-flags dumpconfig

Note: This works only with geth v1.6.0 and above.

Docker quick start

One of the quickest ways to get Ethereum up and running on your machine is by using Docker:

docker run -d --name ethereum-node -v /Users/alice/ethereum:/root \
           -p 8545:8545 -p 30303:30303 \
           ethereum/client-go

This will start geth in snap-sync mode with a DB memory allowance of 1GB, as the above command does. It will also create a persistent volume in your home directory for saving your blockchain as well as map the default ports. There is also an alpine tag available for a slim version of the image.

Do not forget --http.addr 0.0.0.0, if you want to access RPC from other containers and/or hosts. By default, geth binds to the local interface and RPC endpoints are not accessible from the outside.

Programmatically interfacing geth nodes

As a developer, sooner rather than later you'll want to start interacting with geth and the Ethereum network via your own programs and not manually through the console. To aid this, geth has built-in support for a JSON-RPC based APIs (standard APIs and geth specific APIs). These can be exposed via HTTP, WebSockets and IPC (UNIX sockets on UNIX based platforms, and named pipes on Windows).

The IPC interface is enabled by default and exposes all the APIs supported by geth, whereas the HTTP and WS interfaces need to manually be enabled and only expose a subset of APIs due to security reasons. These can be turned on/off and configured as you'd expect.

HTTP based JSON-RPC API options:

• --http Enable the HTTP-RPC server
• --http.addr HTTP-RPC server listening interface (default: localhost)
• --http.port HTTP-RPC server listening port (default: 8545)
• --http.api API's offered over the HTTP-RPC interface (default: eth,net,web3)
• --http.corsdomain Comma separated list of domains from which to accept cross origin requests (browser enforced)
• --ws Enable the WS-RPC server
• --ws.addr WS-RPC server listening interface (default: localhost)
• --ws.port WS-RPC server listening port (default: 8546)
• --ws.api API's offered over the WS-RPC interface (default: eth,net,web3)
• --ws.origins Origins from which to accept WebSocket requests
• --ipcdisable Disable the IPC-RPC server
• --ipcapi API's offered over the IPC-RPC interface (default: admin,debug,eth,miner,net,personal,txpool,web3)
• --ipcpath Filename for IPC socket/pipe within the datadir (explicit paths escape it)

You'll need to use your own programming environments' capabilities (libraries, tools, etc) to connect via HTTP, WS or IPC to a geth node configured with the above flags and you'll need to speak JSON-RPC on all transports. You can reuse the same connection for multiple requests!

Note: Please understand the security implications of opening up an HTTP/WS based transport before doing so! Hackers on the internet are actively trying to subvert Ethereum nodes with exposed APIs! Further, all browser tabs can access locally running web servers, so malicious web pages could try to subvert locally available APIs!

Operating a private network

Maintaining your own private network is more involved as a lot of configurations taken for granted in the official networks need to be manually set up.

Defining the private genesis state

First, you'll need to create the genesis state of your networks, which all nodes need to be aware of and agree upon. This consists of a small JSON file (e.g. call it genesis.json):

{
  "config": {
    "chainId": <arbitrary positive integer>,
    "homesteadBlock": 0,
    "eip150Block": 0,
    "eip155Block": 0,
    "eip158Block": 0,
    "byzantiumBlock": 0,
    "constantinopleBlock": 0,
    "petersburgBlock": 0,
    "istanbulBlock": 0,
    "berlinBlock": 0,
    "londonBlock": 0
  },
  "alloc": {},
  "coinbase": "0x0000000000000000000000000000000000000000",
  "difficulty": "0x20000",
  "extraData": "",
  "gasLimit": "0x2fefd8",
  "nonce": "0x0000000000000042",
  "mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
  "timestamp": "0x00"
}

The above fields should be fine for most purposes, although we'd recommend changing the nonce to some random value so you prevent unknown remote nodes from being able to connect to you. If you'd like to pre-fund some accounts for easier testing, create the accounts and populate the alloc field with their addresses.

"alloc": {
  "0x0000000000000000000000000000000000000001": {
    "balance": "111111111"
  },
  "0x0000000000000000000000000000000000000002": {
    "balance": "222222222"
  }
}

With the genesis state defined in the above JSON file, you'll need to initialize every geth node with it prior to starting it up to ensure all blockchain parameters are correctly set:

$ geth init path/to/genesis.json

Creating the rendezvous point

With all nodes that you want to run initialized to the desired genesis state, you'll need to start a bootstrap node that others can use to find each other in your network and/or over the internet. The clean way is to configure and run a dedicated bootnode:

$ bootnode --genkey=boot.key
$ bootnode --nodekey=boot.key

With the bootnode online, it will display an enode URL that other nodes can use to connect to it and exchange peer information. Make sure to replace the displayed IP address information (most probably [::]) with your externally accessible IP to get the actual enode URL.

Note: You could also use a full-fledged geth node as a bootnode, but it's the less recommended way.

Starting up your member nodes

With the bootnode operational and externally reachable (you can try telnet <ip> <port> to ensure it's indeed reachable), start every subsequent geth node pointed to the bootnode for peer discovery via the --bootnodes flag. It will probably also be desirable to keep the data directory of your private network separated, so do also specify a custom --datadir flag.

$ geth --datadir=path/to/custom/data/folder --bootnodes=<bootnode-enode-url-from-above>

Note: Since your network will be completely cut off from the main and test networks, you'll also need to configure a miner to process transactions and create new blocks for you.

Running a private miner

In a private network setting a single CPU miner instance is more than enough for practical purposes as it can produce a stable stream of blocks at the correct intervals without needing heavy resources (consider running on a single thread, no need for multiple ones either). To start a geth instance for mining, run it with all your usual flags, extended by:

$ geth <usual-flags> --mine --miner.threads=1 --miner.etherbase=0x0000000000000000000000000000000000000000

Which will start mining blocks and transactions on a single CPU thread, crediting all proceedings to the account specified by --miner.etherbase. You can further tune the mining by changing the default gas limit blocks converge to (--miner.targetgaslimit) and the price transactions are accepted at (--miner.gasprice).

Contribution

Thank you for considering helping out with the source code! We welcome contributions from anyone on the internet, and are grateful for even the smallest of fixes!

If you'd like to contribute to go-ethereum, please fork, fix, commit and send a pull request for the maintainers to review and merge into the main code base. If you wish to submit more complex changes though, please check up with the core devs first on our Discord Server to ensure those changes are in line with the general philosophy of the project and/or get some early feedback which can make both your efforts much lighter as well as our review and merge procedures quick and simple.

Please make sure your contributions adhere to our coding guidelines:

• Code must adhere to the official Go formatting guidelines (i.e. uses gofmt).
• Code must be documented adhering to the official Go commentary guidelines.
• Pull requests need to be based on and opened against the master branch.
• Commit messages should be prefixed with the package(s) they modify.
  • E.g. "eth, rpc: make trace configs optional"

Please see the Developers' Guide for more details on configuring your environment, managing project dependencies, and testing procedures.

Contributing to geth.ethereum.org

For contributions to the go-ethereum website, please checkout and raise pull requests against the website branch. For more detailed instructions please see the website branch README or the contributing page of the website.

License

The go-ethereum library (i.e. all code outside of the cmd directory) is licensed under the GNU Lesser General Public License v3.0, also included in our repository in the COPYING.LESSER file.

The go-ethereum binaries (i.e. all code inside of the cmd directory) are licensed under the GNU General Public License v3.0, also included in our repository in the COPYING file.

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