Log Format

Author:

Rohit Goswami

Default format (--format=log)

Each line follows the pattern:

[TIMESTAMP LEVEL] MESSAGE

Where:

  • TIMESTAMP is RFC 3339 with second precision (e.g., 2024-01-15T10:30:00Z)

  • LEVEL is one of: TRACE, DEBUG, INFO, WARN, ERROR

  • MESSAGE is the original stdout/stderr line

Stdout lines are logged at INFO. Stderr lines are logged at WARN.

JSONL format (--format=jsonl)

Each line is a JSON object:

{"ts":"2024-01-15T10:30:00Z","level":"INFO","msg":"gcc -c main.c -o main.o"}

Fields:

Field

Type

Description

ts

string

RFC 3339 timestamp

level

string

Log level

msg

string

Original line

No-timestamp format (--no-timestamp)

Applies only to stdout with --format=log. JSONL stdout always includes ts. Gzip keeps timestamps either way.

Stdout:

[LEVEL] MESSAGE

Gzip file

The gzip file always uses the default format with full timestamps, regardless of --format or --no-timestamp settings. Combined --use-mongodb runs archive the same levels as a local single file (TRACE through ERROR).

Internal log lines

bless adds these internal lines:

  • TRACE level: label and UUID at start. Duration at end only when --use-mongodb is not set

  • ERROR level: command failure messages