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When provisioning resources with OpenTofu, failures and unexpected errors often require deeper inspection. Enabling debug logging surfaces internal details and helps you troubleshoot more effectively. In this guide, you’ll learn how to:
  • Configure log verbosity with TF_LOG
  • Persist logs to disk using TF_LOG_PATH
  • Disable verbose logging when you’re done

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1. Configure Log Verbosity

OpenTofu honors the standard Terraform log levels via the TF_LOG environment variable. You can choose from five levels:
LevelDescription
ERROROnly error messages
WARNWarnings and errors
INFOHigh-level informational messages
DEBUGDetailed execution and decision points
TRACEFull internal trace (most verbose)
Setting TF_LOG=TRACE produces the most comprehensive output, including plugin operations, HTTP requests, and configuration decisions.
To enable debugging, export the desired level: 
export TF_LOG=TRACE
Now, any OpenTofu command will include detailed log entries. For example: 
$ opentofu plan
2023/11/05 10:12:45 [INFO]  OpenTofu version: 1.6.1
2023/11/05 10:12:45 [DEBUG] Attempting to open CLI config file: ~/.opentofu.rc
2023/11/05 10:12:45 [DEBUG] Plugin directory: ~/.terraform.d/plugins
2023/11/05 10:12:45 [INFO]  backend/local: starting Plan operation
2023/11/05T10:12:45.123-0400 [DEBUG] plugin: starting plugin: path=/…/terraform-provider-aws_v3.11.0_x5 pid=34016
Log levels below TRACE can sometimes omit critical details. If you’re troubleshooting core OpenTofu behavior, always default to TF_LOG=TRACE.

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2. Persisting Logs to a File

For lengthy runs or CI environments, capture logs into a file by setting TF_LOG_PATH. All output from TF_LOG will be written to the specified path: 
export TF_LOG_PATH=/tmp/opentofu-debug.log
You can verify the beginning of the log file with: 
head -n 10 /tmp/opentofu-debug.log
Example output: 
2023/11/05 10:12:45 [INFO]  OpenTofu version: 1.6.1
2023/11/05 10:12:45 [INFO]  Go runtime version: go1.14.2
2023/11/05 10:12:45 [DEBUG] CLI args: ["/usr/local/bin/opentofu" "plan"]
2023/11/05 10:12:45 [DEBUG] Loading provider registry from ~/.terraform.d/plugins
2023/11/05 10:12:45 [INFO]  backend/local: starting Plan operation

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3. Disabling Debug Logging

Once you’ve finished troubleshooting, remove the logging environment variables to return to standard output: 
unset TF_LOG
unset TF_LOG_PATH

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See Also

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