Local Logs & Debugging

Q: Where do anchor test logs go?

Test validator stdout and solana logs - enable -- --nocapture for Rust test println output.

Q: How do I see CU per instruction?

Use sol_log_compute_units in program or read total computeUnitsConsumed in meta after optimize passes.

Q: Can I filter logs by program ID?

solana logs supports mention filters - see solana logs --help.

Q: Do CPI logs appear?

Yes - inner invocations indent in logMessages order.

Q: How do I debug custom program errors?

Map numeric codes to #[error_code] enums in Anchor or manual ProgramError variants.

Q: Can I save logs to file?

Redirect solana logs or capture JSON meta from solana transaction.

Q: How do I debug compute budget?

Add ComputeBudgetInstruction::set_compute_unit_limit in client and compare consumed vs limit in meta.

Read program logs, compute unit consumption, and transaction errors on local validators without RPC rate limits.

Recipe

Quick-reference recipe card - copy-paste ready.

solana-test-validator
solana logs
anchor test
solana confirm -v <SIGNATURE>

When to reach for this:

Iterating on msg! output during instruction development.
Measuring CU before mainnet deploy.
Debugging Anchor test failures with full meta.
Comparing local vs devnet error codes.

Working Example

# Terminal 1
solana-test-validator --reset
 
# Terminal 2
solana config set --url http://127.0.0.1:8899
solana logs
 
# Terminal 3
anchor test --skip-local-validator
 
# After failure, inspect signature from test output
solana confirm -v <SIG>

What this demonstrates:

Validator stdout and solana logs both surface program output.
Anchor tests print signatures on failure for confirm -v follow-up.
Local environment removes devnet RPC noise from debugging.

Deep Dive

How It Works

Programs log via msg!, sol_log, and sol_log_compute_units.
Transaction meta includes logMessages and computeUnitsConsumed.
Failed transactions still return logs up to the failing instruction.
Local validator allows unlimited simulateTransaction calls.

Debug Checklist

Signal	Tool	Action
Program lines	`solana logs`	Trace instruction path
Error code	`confirm -v`	Map to program Error enum
CU usage	meta field	Tune compute budget ix
Account state	`solana account`	Verify owners and data

bash Notes

# Anchor verbose test
anchor test -- --nocapture
 
# RUST_LOG for off-chain test harness
RUST_LOG=debug anchor test

Gotchas

Log spam hits limits - excessive msg! truncates logs and burns CU. Fix: log discriminators and summaries only.
Missing logs on success path - instruction skipped due to early guard. Fix: log at branch entry points.
Ignoring CU in local tests - passes locally, fails on congested mainnet. Fix: set compute budget based on simulated CU with headroom.
Wrong terminal order - logs subscriber starts after tx. Fix: start solana logs before sending transactions.
Confusing validator stdout with RPC logs - both show output; correlate with signatures. Fix: include signature in msg! only in dev builds.

Alternatives

Alternative	Use When	Don't Use When
LiteSVM tests	Sub-second Rust unit loops	Wallet client debugging
`simulateTransaction`	Client-side preflight	Streaming live traffic
Surfpool simulate	Mainnet-fork scenarios	Minimal program-only work
devnet `solana logs`	Shared repro with teammates	Fast inner loop

FAQs

Where do anchor test logs go?

Test validator stdout and solana logs - enable -- --nocapture for Rust test println output.

How do I see CU per instruction?

Use sol_log_compute_units in program or read total computeUnitsConsumed in meta after optimize passes.

Why are logs truncated?

Solana caps log bytes per transaction - reduce verbosity.

Can I filter logs by program ID?

solana logs supports mention filters - see solana logs --help.

Do CPI logs appear?

Yes - inner invocations indent in logMessages order.

How do I debug custom program errors?

Map numeric codes to #[error_code] enums in Anchor or manual ProgramError variants.

Does local debugging match mainnet?

Execution semantics align on Agave 4.1.1; congestion and priority fee paths differ.

Can I save logs to file?

Redirect solana logs or capture JSON meta from solana transaction.

What about LiteSVM logs?

LiteSVM 0.6.x captures logs in test assertions without WebSocket subscriptions.

How do I debug compute budget?

Add ComputeBudgetInstruction::set_compute_unit_limit in client and compare consumed vs limit in meta.

Logs & Debugging - CLI log commands
solana-test-validator - local cluster
Estimating Compute Units - CU tuning
Testing Basics - test pyramid

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Recipe

Quick-reference recipe card - copy-paste ready.

solana-test-validator
solana logs
anchor test
solana confirm -v <SIGNATURE>

When to reach for this:

Iterating on msg! output during instruction development.
Measuring CU before mainnet deploy.
Debugging Anchor test failures with full meta.
Comparing local vs devnet error codes.

Working Example

# Terminal 1
solana-test-validator --reset
 
# Terminal 2
solana config set --url http://127.0.0.1:8899
solana logs
 
# Terminal 3
anchor test --skip-local-validator
 
# After failure, inspect signature from test output
solana confirm -v <SIG>

What this demonstrates:

Validator stdout and solana logs both surface program output.
Anchor tests print signatures on failure for confirm -v follow-up.
Local environment removes devnet RPC noise from debugging.

Deep Dive

How It Works

Programs log via msg!, sol_log, and sol_log_compute_units.
Transaction meta includes logMessages and computeUnitsConsumed.
Failed transactions still return logs up to the failing instruction.
Local validator allows unlimited simulateTransaction calls.

Debug Checklist

Signal	Tool	Action
Program lines	`solana logs`	Trace instruction path
Error code	`confirm -v`	Map to program Error enum
CU usage	meta field	Tune compute budget ix
Account state	`solana account`	Verify owners and data

bash Notes

# Anchor verbose test
anchor test -- --nocapture
 
# RUST_LOG for off-chain test harness
RUST_LOG=debug anchor test

Gotchas

Log spam hits limits - excessive msg! truncates logs and burns CU. Fix: log discriminators and summaries only.
Missing logs on success path - instruction skipped due to early guard. Fix: log at branch entry points.
Ignoring CU in local tests - passes locally, fails on congested mainnet. Fix: set compute budget based on simulated CU with headroom.
Wrong terminal order - logs subscriber starts after tx. Fix: start solana logs before sending transactions.
Confusing validator stdout with RPC logs - both show output; correlate with signatures. Fix: include signature in msg! only in dev builds.

Alternatives

Alternative	Use When	Don't Use When
LiteSVM tests	Sub-second Rust unit loops	Wallet client debugging
`simulateTransaction`	Client-side preflight	Streaming live traffic
Surfpool simulate	Mainnet-fork scenarios	Minimal program-only work
devnet `solana logs`	Shared repro with teammates	Fast inner loop

FAQs

Where do anchor test logs go?

Test validator stdout and solana logs - enable -- --nocapture for Rust test println output.

How do I see CU per instruction?

Use sol_log_compute_units in program or read total computeUnitsConsumed in meta after optimize passes.

Why are logs truncated?

Solana caps log bytes per transaction - reduce verbosity.

Can I filter logs by program ID?

solana logs supports mention filters - see solana logs --help.

Do CPI logs appear?

Yes - inner invocations indent in logMessages order.

How do I debug custom program errors?

Map numeric codes to #[error_code] enums in Anchor or manual ProgramError variants.

Does local debugging match mainnet?

Execution semantics align on Agave 4.1.1; congestion and priority fee paths differ.

Can I save logs to file?

Redirect solana logs or capture JSON meta from solana transaction.

What about LiteSVM logs?

LiteSVM 0.6.x captures logs in test assertions without WebSocket subscriptions.

How do I debug compute budget?

Add ComputeBudgetInstruction::set_compute_unit_limit in client and compare consumed vs limit in meta.

Logs & Debugging - CLI log commands
solana-test-validator - local cluster
Estimating Compute Units - CU tuning
Testing Basics - test pyramid

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Local Logs & Debugging

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Local Logs & Debugging