confessecrets

confessecrets

Every config file has something to confess.

A secret scanner for structured configuration files that gets your configs to spill their guts. It walks a file or directory, hears out every confession, and reports likely secrets as newline-delimited JSON (NDJSON).

It coaxes out secrets two complementary ways:

• Name-driven — a key whose name practically advertises guilt (e.g. password, api_key, client_secret) paired with a populated, secret-looking value.
• Value-driven — a value whose shape gives it away (gitleaks-style patterns such as AKIA…, ghp_…, sk_live_…), no matter how innocent its key name claims to be.

Supported formats: JSON / JSONC, YAML, XML (including .NET App.config / web.config and other .config files), dotenv (.env, .env.*, *.env), Java properties (.properties), and INI (.ini).

It also scans source code — Python, JavaScript, TypeScript, Go, Java, C#, Ruby, PHP, Kotlin, and Rust — with tree-sitter, so it can tell a hardcoded secret from a runtime lookup. password = "hunter2" confesses; password = os.environ.get("SECRET") does not, because the value is a call, not a string literal. See Scanning source code.

Requirements

• Go 1.26+ (see go.mod)

Build

# Build a binary into ./confessecrets
go build -o confessecrets ./cmd/confessecrets

# Or install it onto your PATH (into $GOBIN / $GOPATH/bin)
go install github.com/rezen/confessecrets/cmd/confessecrets@latest

Releasing

Stamp the commit and build date into the binary via -ldflags so they show up in version.String() (the Number const is bumped in the source — see pkg/version/version.go):

go build -ldflags "\
  -X github.com/rezen/confessecrets/pkg/version.Commit=$(git rev-parse --short HEAD) \
  -X github.com/rezen/confessecrets/pkg/version.Date=$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  -o confessecrets ./cmd/confessecrets

Run

The scanner is the cmd/confessecrets package — run the package, not a single file:

# From source
go run ./cmd/confessecrets -config config.yaml -path ./path/to/scan

# Or with the built binary
./confessecrets -config config.yaml -path ./path/to/scan

Note: go run main.go will fail — the program is split across several files in the package. Use go run ./cmd/confessecrets (or go run . from inside that directory).

Findings are written as NDJSON to stdout by default. Redirect or tee to save:

go run ./cmd/confessecrets -path ~/repos | tee found.txt

Flags

Exit codes

This makes it CI-friendly: a non-zero exit fails the job the moment something confesses.

Output

One JSON object per confession, per line. Values are redacted — what's said in the confessional stays in the confessional — but the SHA-256 of the raw value is included so you can correlate without storing the secret itself.

{
  "file": "app/config.py",
  "line": 12,
  "lang": "python",
  "level": "high",
  "name_path": "value_pattern",
  "value_path": "value_pattern",
  "name": "ci_token",
  "value": "ghp_********wxyz",
  "raw_value": "ghp_0123456789abcdefghijklmnopqrstuvwxyz",
  "value_sha256": "6675cd0c…",
  "entropy": 4.71,
  "name_value_distance": 38,
  "reason": "gitleaks:github-pat",
  "tags": ["value-pattern"]
}

Every finding carries a lang field naming the source language or config format it came from (e.g. python, json, dotenv), and a level: high for a detected secret (the default) or info for an informational match such as a recognized service URL (info:azure-app-service, info:aws-lambda-url). For the line-oriented formats and source code the 1-based line is set and the redundant path is omitted; structured documents (cleanly parsed JSON/YAML/INI) instead carry a path locator like $.db.password and omit line. A value-shape match in a named assignment keeps that name (e.g. ci_token above), not an empty one.

The tags array holds the id of any tag-action filter the finding matched and any correlation tag. It is omitted when a finding has no tags.

Every finding carries the entropy field: the Shannon entropy (bits/symbol) of the raw value, rounded to two decimals — handy for triage and tuning the min_entropy / high_entropy_threshold thresholds.

name_value_similarity scores how closely the value resembles its key name, in [0,1] where 1 is identical. It is the max of normalized Levenshtein and Jaro-Winkler similarity (both case-insensitive) — Jaro-Winkler rewards the shared prefixes typical of placeholder mutations (secret/secrets, passwd/passw0rd). A high score flags a value echoing its key; a low one points to a genuine opaque secret. Set the rule's max_name_value_similarity to drop name-driven findings at or above a chosen similarity (0 disables it).

The reason field explains why it was flagged — e.g. jwt_indicator, url_credentials, private_key_indicator, name_indicates_secret for a name-driven finding, or gitleaks:<rule-id> for a value-pattern match. Findings can also carry an optional meta object with value-derived context:

• jwt — for JSON Web Token values: the decoded header, the parsed claims (issuer, iat, expiration, is_expired), and any remaining claims under extra.
• username, host, url — derived from URL credentials (user:pass@host) and connection strings.
• client_id, client_key — derived from connection strings and from correlated partner findings (e.g. the client_id paired with a client_secret).

All meta fields are optional and omitted when absent.

A finding may also carry a correlated array holding partner findings folded into it by a correlation rule (e.g. the client_id paired with this client_secret). Correlated partners are always in the same file as their primary, so each embedded entry omits the redundant file field and keeps only its in-file location (path).

Scanning source code

Beyond structured config, confessecrets scans source files in Python, JavaScript/TypeScript, Go, Java, C#, Ruby, PHP, Kotlin, and Rust. It parses each file with tree-sitter and inspects the syntax of each assignment, which lets it avoid the classic false positive that trips up regex-only scanners:

password = "hunter2supersecret"               # flagged — value is a string literal
api_token = os.environ.get("API_TOKEN")       # not flagged — value is a runtime lookup
secret = f"sk_{var}"                          # not flagged — interpolated, not a literal

Detection covers several shapes:

• name-driven — a secret-looking variable assigned a string literal (password = "…").
• value-driven — any string literal whose shape matches a gitleaks pattern, regardless of the surrounding name ("AKIA…", "ghp_…").
• env fallback — a hardcoded default behind an environment/config lookup, whether passed as an argument (os.getenv("DB_PASSWORD", "hunter2")) or via a logical default (process.env.API_KEY || "fallback", GetEnvironmentVariable(…) ?? "fallback").
• call argument — a secret passed into any call when the assignment target signals a secret (password = vault.fetch("key", "s3cr3t!")).

Because it reads the syntax tree, it skips what regex scanners get wrong: runtime lookups (the value is a call), interpolated/dynamic strings (f-strings, template literals), and comparisons (process.env.MODE == "prod" is not a default). Call arguments and defaults are gated more strictly to avoid flagging prompts and labels (e.g. getpass("Enter password: ")).

No setup required

Parsing uses a pure-Go tree-sitter runtime (gotreesitter) with the grammars embedded in the binary. There is nothing to install, download, or compile — no libtree-sitter, no per-language grammar libraries, no C toolchain. The build stays CGO-free, so confessecrets cross-compiles to any GOOS/GOARCH from a single machine (CGO_ENABLED=0).

To actually scan source files, add their globs to the config allow list (e.g. "**/*.py", "**/*.go"); the default config.yaml already includes them.

Note: .tsx is parsed with the TypeScript grammar, which does not understand JSX; embedded-JSX files may parse partially.

Configuration

The config (default config.yaml) decides whose confessions you hear — which files are scanned and what actually counts as a secret worth flagging.

files:
  allow:                 # glob patterns to scan (doublestar syntax)
    - "**/*.json"
    - "**/*.yaml"
    - "**/*.yml"
    - "**/.env"
    - "**/.env.*"
    - "**/*.env"
    - "**/*.xml"
    - "**/*.properties"
    - "**/*.ini"
  deny:                  # glob patterns to skip (checked before allow)
    - "**/test/**"
    - "**/.git/**"
    - "**/node_modules/**"

rules:
  - name_paths: [name, key, field]      # keys that may name a secret (structured)
    value_paths: [value, val, secret]   # sibling keys holding the value
    # A name matching ANY entry signals a secret. Each entry is either a bare
    # regex string or a {name, regex} mapping (the name is a label for the rule).
    name_regexes:
      - '(?i)(secret|token|api[_-]?key|password|credential|auth)'
      - name: camelcase-key
        regex: '(?-i:[a-z0-9]Key([A-Z0-9_]|$))'
    min_value_len: 8                     # default 8 when omitted
    min_entropy: 2.0                     # gate: drop low-variety placeholders (0 = off)
    high_entropy_threshold: 0            # flag any opaque value this random (0 = off)
    max_name_value_similarity: 0.85      # drop values this similar to the name (0 = off)

    # Names matching any of these are never treated as secrets, even if they
    # match a name pattern (e.g. "label"/"labelKey").
    ignore_name_patterns:
      - '(?i)(label|text|title|description)'

    # Values starting with these prefixes are ignored (vault refs, placeholders…).
    ignore_value_prefixes:
      - vault://
      - ${

    # Values matching these regexes are ignored.
    ignore_value_patterns:
      - '^ENC\[.*\]$'
      - '^arn:aws:secretsmanager:'

# Extra stopwords applied across all rules, on top of the built-in set (see below).
stopwords:
  - redacted
  - internalfixture

Value-pattern (gitleaks) scanning is built in and always on; it honors ignore_value_prefixes / ignore_value_patterns so you can suppress false positives.

Two optional entropy controls measure the Shannon entropy (bits/symbol) of a value to catch what the name and shape rules miss:

• min_entropy is a gate: a value flagged only because its key name looks secret-y must clear this threshold, so repetitive placeholders (aaaaaaaa) are dropped. Values with a definite secret reason (JWT, private key, URL credentials) bypass the gate.
• high_entropy_threshold is a detector: any opaque token-like value (whitespace-free, ≤200 chars) whose entropy meets it is flagged regardless of key name, reported as high_entropy:<measured>. Built-in gitleaks and custom detectors take precedence, and rule ignore_* suppressions still apply. It is noisy when scanning source code (many string literals sit near the secret range), so it ships disabled; enable it (e.g. 4.5) for config-only scans (-scan config). Keep it above ~4.0, where hex digests and UUIDs sit.

high_entropy_threshold defaults to 0 (disabled); min_entropy is a pure filter and is safe to leave on.

A value that merely echoes its key name — password="password", api_key="your-api-key", token="TOKEN", secret="<my-secret>" — is treated as a placeholder and dropped automatically. The comparison ignores case, separators, camelCase, and common filler words ("your", "my", "example", …), so these obvious fakes never count as findings.

A value that is, or embeds, a variable/template placeholder is likewise dropped — the real secret is substituted in later, so the literal text is not a credential. The brace/paren forms ${DB_HOST}, $(secret), and {{ db_host }} are recognized anywhere in the value (e.g. password=${PW} in a connection string); the single-character @DB_HOST@ and %DB_HOST% forms are recognized only as a whole value, since @ and % also occur inside genuine secrets.

A name-driven candidate is also dropped when its value contains a stopword — a common word or placeholder fragment that marks it as a non-secret. The built-in set is gitleaks' DefaultStopWords, matched the same way gitleaks does: case-insensitively, by substring (a value containing changeme, example, test, … anywhere is skipped). The built-in set is always on; add project-specific entries with the top-level stopwords list, which applies across all rules (also matched case-insensitively by substring). Values carrying a definite secret reason (JWT, private key, URL credentials) and built-in gitleaks value patterns are matched before this check, so a real token is never lost to a stopword.

Custom value-pattern detectors

Beyond the built-in gitleaks patterns, you can define your own value-shape detectors using trufflehog's custom-detector schema. Each detector flags a value by its shape alone — regardless of the surrounding key name — and matches are tagged custom:<name> in the reason field.

detectors:
  - name: acme-api-key
    keywords:            # at least one must appear in the value or its key name
      - acme             #   (case-insensitive); omit for an always-on detector
    regex:               # every named regex must match the value
      key: 'AKME-[0-9a-f]{32}'
    primary_regex_name: key       # which regex supplies the reported value
    exclude_regexes_match:        # drop matches whose value matches any of these
      - '^AKME-0+$'
    exclude_words:                # drop a candidate when any of these is present
      - example
    entropy: 3.0                  # require this minimum Shannon entropy (bits/symbol)

A detector fires when at least one keyword is present (in the value or its key name) and every named regex matches the value. When a regex defines a capture group, its first group is the reported secret; otherwise the whole match is. primary_regex_name (optional) selects which regex's match is reported and entropy/exclude-checked, defaulting to the alphabetically first. The exclude_* and entropy fields are optional false-positive filters. Custom detectors honor the same ignore_value_prefixes / ignore_value_patterns suppressions as the built-in patterns, and a built-in gitleaks match takes precedence over a custom one for the same value.

Notes:

• Detection is per value: a multi-regex detector requires every regex to match the same scalar value (most custom detectors use a single regex).
• Live HTTP verify endpoints from trufflehog's schema are not supported — confessecrets is an offline scanner that redacts values rather than sending them anywhere — so that field is ignored if present.

Custom filters

The top-level filter is a list of filter rules, each an expr-lang expression evaluated against every finding. When a rule's expression is true for a finding, its action decides what happens:

• filter (the default) — drop the finding. This is the suppression behavior: silence whole classes of false positives by their computed properties.
• tag — keep the finding and add the rule's id to its tags. A flexible way to label findings (e.g. for downstream triage) without removing them.

A rule is written either as a bare string (an expression with the default filter action) or as an {id, action, filter} mapping:

filter:
  # Bare string → filter action: drop low-entropy values whose name echoes the value.
  - 'entropy <= 4 && name_value_similarity > 0.65'
  # Mapping → tag action: keep value-pattern hits, tagged "value-pattern".
  - id: value-pattern
    action: tag
    filter: 'reason startsWith "gitleaks:"'

Every rule runs against every finding, so one finding can be tagged by several rules; the first filter-action rule to match drops it. A tag rule must carry an id (the tag it applies). Leave the list empty to disable filtering.

The variables available to an expression are:

expr-lang operators and built-ins work too, so richer rules like value matches "(?i)example$", name contains "test", or reason startsWith "gitleaks:" are valid. Each expression is type-checked at load time, so a bad filter fails fast.

To see what the filter-action rules are removing, run with -show-filtered: excluded findings are kept in the output with "filtered": true and a "filtered_reason" holding the matched expression, rather than being dropped. Filtered findings are informational and do not affect the exit code, so a scan whose only findings are filtered still exits 0.

Repo-local config

When the scan descends into a repository root — a directory containing a .git entry (a normal clone, or a .git file for worktrees/submodules) — the scanner looks for a repo-local config there and uses it for every file in that repository. The file names checked, in order, are:

.confessecrets.yaml
.confessecrets.yml

This lets each repository carry its own allow/deny globs and rules (e.g. an internal repo that wants stricter rules, or one that needs extra ignore_value_* entries). A repo-local config has the same shape as the main config and fully replaces the base config for that repository's files.

Semantics:

• A repository boundary is respected: a repo without its own config uses the base -config, even if a parent repository defines one. Nested repos use the config of their nearest enclosing repository.
• A repo-local config that fails to load or compile is reported to stderr and skipped — the scan continues with the base config for that repo.
• Pass -repo-config=false to ignore repo-local configs entirely and apply the base -config everywhere.

Test

go test ./...
go vet ./...

Sample golden-file tests

TestSamples (in pkg/scanner/samples_test.go) is a golden-file suite driven by the samples/ directory. Every sample (e.g. samples/function_url.py) has a sibling .verify file (samples/function_url.verify) holding the exact NDJSON the scanner should emit for it — one JSON finding per line. The test scans each sample with the repo's config.yaml and asserts the output matches its .verify byte for byte.

# Run just the sample suite (one subtest per sample)
go test ./pkg/scanner/ -run TestSamples -v

To add a case, drop in a sample file plus its .verify; the test picks it up automatically. To seed a new sample's .verify — or refresh expectations after an intended behavior change — regenerate the golden files and review the diff:

go test ./pkg/scanner/ -run TestSamples -update

Project layout

cmd/confessecrets/   CLI entry point (flag parsing, output)
pkg/scanner/        library: config, file walking, detection
  models.go         types (Config, Rule, RuleSet, Finding, Meta, Detector…)
  files.go          config loading/compiling, file walking/filtering, format dispatch
  detect.go         per-format detectors + classification helpers
  patterns.go       gitleaks-style value patterns
  detectors.go      custom (trufflehog-style) value-pattern detectors