Find Flipt feature flags in your codebase

brew tap flipt-io/brew
brew install ffs

TODO

A CLI tool to find Flipt feature flags in code

Usage: ffs [OPTIONS] --language <LANGUAGE>

Options:
  -l, --language <LANGUAGE>    [possible values: go]
  -o, --output <OUTPUT>        Path to output file [default: STDOUT]
  -f, --format <FORMAT>        [default: text] [possible values: json, text]
  -d, --dir <DIR>              Path to directory to scan [default: .]
  -n, --namespace <NAMESPACE>  Namespace to filter [default: '']
  -c, --context                Display lines of context around flag
  -h, --help                   Print help
  -V, --version                Print version

• Rust - install

With args:

$ cargo run -- -l go

$ cargo build

• Go
• TypeScript

Other language support is planned, but not yet implemented:

• Python #43
• Java #44
• Rust #45

This project uses Conventional Commits for commit messages. This allows us to automate the release process and generate a changelog.

1. Add a new language to the SupportedLanguage enum in src/types/language.rs
2. Add new match arms in src/types/language.rs to handle the new language (From and Display traits).
3. Add a new set of rules for the language in rules. The rules are written in S-Expression format and the syntax is documented in the TreeSitter Query docs. Note: the filename must match the language name in the enum.
4. Add a new set of examples in examples for the new language.

Currently, the CLI tool is split into two parts:

• Parsing
• Reporting

The parsing step looks for instances of Flipt evaluation and flag retrieval methods:

• GetFlag
• Boolean
• Variant

It accomplishes this by:

1. Using the Rust tree-sitter bindings and Language specific tree-sitter grammar ex: Go to build a syntax tree.
2. Then use a TreeSitter query to look for the nodes that we care about, that match the signature of our known Evaluate/GetFlag/Boolean/Variant methods and extract the value of the FlagKey and optionally NamespaceKey fields.

The query rules are written as an S-Expression: ie: go.scm

The tool takes output of the parser step and reports the results to the CLI.

ffs -l go

Found 6 results:

- Flag: [ Key: bar, Namespace: production ]
  File: ./examples/go/evaluation.go
  Line: [ Start: 31, End: 39 ]
  Column: [ Start: 11, End: 4 ]

Or as JSON: ffs -l go -f json

[
  {
    "namespaceKey": "production",
    "key": "bar",
    "context": [
      "\t\tNamespaceKey: \"default\",",
      "\t\tFlagKey:      \"foo\",",
      "\t\tContext: map[string]string{",
      "\t\t\t\"bar\": \"boz\",",
      "\t\t},",
      "\t})",
      "\tif err != nil {",
      "\t\tpanic(err)",
      "\t}",
      "",
      "\t_, err = client.Flipt().Evaluate(context.TODO(), &flipt.EvaluationRequest{",
      "\t\tEntityId:     \"1\",",
      "\t\tNamespaceKey: \"production\",",
      "\t\tFlagKey:      \"bar\",",
      "\t\tContext: map[string]string{",
      "\t\t\t\"bar\": \"boz\",",
      "\t\t},",
      "\t})",
      "\tif err != nil {",
      "\t\tpanic(err)",
      "\t}",
      "",
      "\t_, err = client.Flipt().Evaluate(context.TODO(), &flipt.EvaluationRequest{",
      "\t\tEntityId: \"1\",",
      "\t\tFlagKey:  \"boz\",",
      "\t\tContext: map[string]string{",
      "\t\t\t\"bar\": \"boz\",",
      "\t\t},"
    ],
    "location": {
      "file": "./examples/go/basic.go",
      "startLine": 36,
      "startColumn": 11,
      "endLine": 43,
      "endColumn": 4
    }
  },

The JSON format is useful for integrating with other tools, and also provides the context code around the flag usage.

You can also get the context output in the text format by providing the --context flag:

ffs -l go --context

- Flag: [ Key: boz, Namespace: default ]
  File: ./examples/go/basic.go
  Line: [ Start: 48, End: 54 ]
  Column: [ Start: 11, End: 4 ]

/```
  NamespaceKey: "production",
  FlagKey:      "bar",
  Context: map[string]string{
   "bar": "boz",
  },
 })
 if err != nil {
  panic(err)
 }

 _, err = client.Flipt().Evaluate(context.TODO(), &flipt.EvaluationRequest{
  EntityId: "1",
  FlagKey:  "boz",
  Context: map[string]string{
   "bar": "boz",
  },
 })
 if err != nil {
  panic(err)
 }

 flag, err := client.Flipt().GetFlag(context.TODO(), &flipt.GetFlagRequest{
  Key: "foo",
 })
 if err != nil {
  panic(err)
 }
/```