01_hello_world

🛹 Demo 1: Hello World

• -> I want to create the demo from scratch and learn
• -> I just want to run the demo

Create the demo from scratch

1. Initialize a new Rust library via Cargo:

cargo init hello_world --lib
cd hello_world
cargo add solana-program

this creates a very basic Solana Rust program following this layout:

.
├── Cargo.toml
└── src
    └── lib.rs

2. Modify Cargo.toml to the following:

[package]
name = "hello_world"
version = "0.1.0"

[lib]
name = "hello_world"
crate-type = ["cdylib", "lib"]

[dependencies]
// add the right version given by the cmd $ solana-install list
solana-program = "=1.x.x"

3. Write the source code of the program inside src/lib.rs

At the top, we import the solana-program crate and bring needed items into the local namespace:

extern crate solana_program;

use solana_program::{
    account_info::AccountInfo,
    entrypoint,
    entrypoint::ProgramResult,
    pubkey::Pubkey,
    msg,
  };

• Every Solana program must define an entrypoint that tells the runtime where to start executing the code on-chain.
  • The entry point should provide a public function named process_instruction:

entrypoint!(process_instruction);

pub fn process_instruction(
   _program_id: &Pubkey,
   _accounts: &[AccountInfo],
   _instruction_data: &[u8]
  ) -> ProgramResult {
  
   msg!("Only possible on Solana");
  
   Ok(())
}

• Note that every on-chain program should return the Ok result enum with value ().
  • This tells the Solana runtime that the program executed successfully.

Build and Deploy

1. Make sure you have a local cluster running:

solana-test-validator

2. Compile by running the following command from the /01_hello_world directory:

cargo build-sbf

If you get any errors see troubleshooting

You can find the the compiled program's .so file inside ./target/deploy:

find . -name '*.so'

3. Now, deploy it:

solana program deploy ./target/deploy/hello_world.so 

The program's public address (program id) will be displayed.

Try checking your Solana wallet's balance to see how much it costs to deploy this simple program.

solana balance