A diff tool for OpenAPI Spec 3.

docker run --rm -t tufin/oasdiff -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

• Generate a diff report in YAML, Text/Markdown or HTML
• Run from Docker
• Embed in your go program
• Compare specs from the file system or over http/s
• Compare specs in YAML or JSON format
• Comprehensive diff including all aspects of OpenAPI Specification: paths, operations, parameters, request bodies, responses, schemas, enums, callbacks, security etc.
• Detect breaking changes
• Allow non-breaking removal of deprecated resources
• Support path prefix modification
• GitHub Action

go install github.com/tufin/oasdiff@latest

brew tap tufin/homebrew-tufin
brew install oasdiff

Copy binaries from latest release

oasdiff -help

Usage of oasdiff:
  -base string
    	path of original OpenAPI spec in YAML or JSON format
  -breaking-only
    	display breaking changes only
  -deprecation-days int
    	minimal number of days required between deprecating a resource and removing it without being considered 'breaking'
  -exclude-description
    	ignore changes to descriptions
  -exclude-examples
    	ignore changes to examples
  -fail-on-diff
    	fail with exit code 1 if a difference is found
  -filter string
    	if provided, diff will include only paths that match this regular expression
  -filter-extension string
    	if provided, diff will exclude paths and operations with an OpenAPI Extension matching this regular expression
  -format string
    	output format: yaml, text or html (default "yaml")
  -max-circular-dep int
    	maximum allowed number of circular dependencies between objects in OpenAPI specs (default 5)
  -prefix string
    	deprecated. use -prefix-revision instead
  -prefix-base string
    	if provided, paths in original (base) spec will be prefixed with the given prefix before comparison
  -prefix-revision string
    	if provided, paths in revised (revision) spec will be prefixed with the given prefix before comparison
  -revision string
    	path of revised OpenAPI spec in YAML or JSON format
  -strip-prefix-base string
    	if provided, this prefix will be stripped from paths in original (base) spec before comparison
  -strip-prefix-revision string
    	if provided, this prefix will be stripped from paths in revised (revision) spec before comparison
  -summary
    	display a summary of the changes instead of the full diff
  -version
    	show version and quit

All arguments can be passed with one or two leading minus signs.
For example, -breaking-only and --breaking-only are equivalent.

oasdiff -base data/openapi-test1.yaml -revision data/openapi-test2.yaml

The default output format is YAML.
No output means that the diff is empty, or, in other words, there are no changes.

oasdiff -format text -base data/openapi-test1.yaml -revision data/openapi-test2.yaml

The Text/Markdown diff report provides a simplified and partial view of the changes.
To view all details, use the default format: YAML.
If you'd like to see additional details in the text/markdown report, please submit a feature request.

oasdiff -format text -base data/openapi-test1.yaml -revision data/openapi-test2.yaml

The HTML diff report provides a simplified and partial view of the changes.
To view all details, use the default format: YAML.
If you'd like to see additional details in the HTML report, please submit a feature request.

oasdiff -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

oasdiff -breaking-only -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

See breaking changes

oasdiff -fail-on-diff -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

oasdiff -fail-on-diff -breaking-only -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

oasdiff -format text -filter "/api" -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

Filters are applied recursively at all levels. For example, if a path contains a callback, the filter will be applied both to the path itself and to the callback path. To include such a nested change, use a regular expression that contains both paths, for example -filter "path|callback-path"

oasdiff -format text -filter-extension "x-beta" -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

Notes:

1. OpenAPI Extensions can be defined both at the path level and at the operation level. Both are matched and excluded with this flag.
2. If a path or operation has a matching extension only in one of the specs, but not in the other, it will appear as Added or Deleted.

oasdiff -exclude-description -exclude-examples -format text -base data/openapi-test1.yaml -revision data/openapi-test3.yaml

oasdiff -summary -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

To run with docker just replace the oasdiff command by docker run --rm -t tufin/oasdiff, for example:

docker run --rm -t tufin/oasdiff -format text -base https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test1.yaml -revision https://raw.githubusercontent.com/Tufin/oasdiff/main/data/openapi-test3.yaml

docker run --rm -t -v $(pwd)/data:/data:ro tufin/oasdiff -base /data/openapi-test1.yaml -revision /data/openapi-test3.yaml

Replace $(pwd)/data by the path that contains your files.
Note that the -base and -revision paths must begin with /.

oasdiff -format text -base data/openapi-test1.yaml -revision data/openapi-test5.yaml

POST /register POST /subscribe

GET /api/{domain}/{project}/badges/security-score

• Modified query param: filter
  • Content changed
    • Modified media type: application/json
      • Schema changed
        • Required changed
          • New required property: type
• Modified query param: image
  • Examples changed
    • Deleted example: 0
• Modified query param: token
  • Schema changed
    • MaxLength changed from 29 to null
• Modified header param: user
  • Schema changed
    • Schema added
  • Content changed
    • Deleted media type: application/json
• Modified cookie param: test
  • Content changed
    • Modified media type: application/json
      • Schema changed
        • Type changed from 'object' to 'string'
• Responses changed
  • New response: default
  • Deleted response: 200
  • Modified response: 201
    • Content changed
      • Modified media type: application/xml
        • Schema changed
          • Type changed from 'string' to 'object'

GET /api/{domain}/{project}/install-command

• Deleted header param: network-policies
• Responses changed
  • Modified response: default
    • Description changed from 'Tufin1' to 'Tufin'
    • Headers changed
      • Deleted header: X-RateLimit-Limit
• Servers changed
  • New server: https://www.tufin.io/securecloud

Security Requirements changed

• Deleted security requirements: bearerAuth

Servers changed

• Deleted server: tufin.com

oasdiff -base data/openapi-test1.yaml -revision data/openapi-test5.yaml

info:
  title:
    from: Tufin
    to: Tufin1
  contact:
    added: true
  license:
    added: true
  version:
    from: 1.0.0
    to: 1.0.1
paths:
  deleted:
    - /register
    - /subscribe
  modified:
    /api/{domain}/{project}/badges/security-score:
      operations:
        modified:
          GET:
            tags:
              deleted:
                - security
            parameters:
              modified:
                cookie:
                  test:
                    content:
                      mediaTypeModified:
                        application/json:
                          schema:
                            type:
                              from: object
                              to: string
                header:
                  user:
                    schema:
                      schemaAdded: true
                    content:
                      mediaTypeDeleted:
                        - application/json
                query:
                  filter:
                    content:
                      mediaTypeModified:
                        application/json:
                          schema:
                            required:
                              stringsdiff:
                                added:
                                  - type
                  image:
                    examples:
                      deleted:
                        - "0"
                  token:
                    schema:
                      maxLength:
                        from: 29
                        to: null
            responses:
              added:
                - default
              deleted:
                - "200"
              modified:
                "201":
                  content:
                    mediaTypeModified:
                      application/xml:
                        schema:
                          type:
                            from: string
                            to: object
      parameters:
        deleted:
          path:
            - domain
    /api/{domain}/{project}/install-command:
      operations:
        modified:
          GET:
            parameters:
              deleted:
                header:
                  - network-policies
            responses:
              modified:
                default:
                  description:
                    from: Tufin1
                    to: Tufin
                  headers:
                    deleted:
                      - X-RateLimit-Limit
            servers:
              added:
                - https://www.tufin.io/securecloud
endpoints:
  deleted:
    - method: POST
      path: /register
    - method: POST
      path: /subscribe
  modified:
    ? method: GET
      path: /api/{domain}/{project}/install-command
    : parameters:
        deleted:
          header:
            - network-policies
      responses:
        modified:
          default:
            description:
              from: Tufin1
              to: Tufin
            headers:
              deleted:
                - X-RateLimit-Limit
      servers:
        added:
          - https://www.tufin.io/securecloud
    ? method: GET
      path: /api/{domain}/{project}/badges/security-score
    : tags:
        deleted:
          - security
      parameters:
        modified:
          cookie:
            test:
              content:
                mediaTypeModified:
                  application/json:
                    schema:
                      type:
                        from: object
                        to: string
          header:
            user:
              schema:
                schemaAdded: true
              content:
                mediaTypeDeleted:
                  - application/json
          query:
            filter:
              content:
                mediaTypeModified:
                  application/json:
                    schema:
                      required:
                        stringsdiff:
                          added:
                            - type
            image:
              examples:
                deleted:
                  - "0"
            token:
              schema:
                maxLength:
                  from: 29
                  to: null
      responses:
        added:
          - default
        deleted:
          - "200"
        modified:
          "201":
            content:
              mediaTypeModified:
                application/xml:
                  schema:
                    type:
                      from: string
                      to: object
security:
  deleted:
    - bearerAuth
servers:
  deleted:
    - tufin.com
tags:
  deleted:
    - security
    - reuven
externalDocs:
  deleted: true
components:
  schemas:
    added:
      - requests
    modified:
      network-policies:
        additionalPropertiesAllowed:
          from: true
          to: false
      rules:
        additionalPropertiesAllowed:
          from: null
          to: false
  parameters:
    deleted:
      header:
        - network-policies
  headers:
    deleted:
      - new
    modified:
      test:
        schema:
          additionalPropertiesAllowed:
            from: true
            to: false
      testc:
        content:
          mediaTypeModified:
            application/json:
              schema:
                type:
                  from: object
                  to: string
  requestBodies:
    deleted:
      - reuven
  responses:
    added:
      - default
    deleted:
      - OK
  securitySchemes:
    deleted:
      - OAuth
    modified:
      AccessToken:
        type:
          from: http
          to: oauth2
        scheme:
          from: bearer
          to: ""
        OAuthFlows:
          added: true

The default output format, YAML, provides a full view of all diff details.
Note that no output in YAML format signifies that the diff is empty, or, in other words, there are no changes.
Other formats: text, markdown, and HTML, are designed to be more user-friendly by providing only the most important parts of the diff, in a simplified format.
If you wish to include additional details in non-YAML formats, please open an issue.

OpenAPI Specification has a hierarchical model of Paths and Operations (HTTP methods).
oasdiff respects this hierarchy and displays a hierarchical diff with path changes: added, deleted and modified, and within the latter, "modified" section, another set of operation changes: added, deleted and modified. For example:

paths:
    deleted:
        - /register
        - /subscribe
    modified:
        /api/{domain}/{project}/badges/security-score:
            operations:
                modified:
                    GET:

oasdiff also outputs an alternate simplified diff per "endpoint" which is a combination of Path + Operation, for example:

endpoints:
    deleted:
        - method: POST
          path: /subscribe
        - method: POST
          path: /register
    modified:
        ?   method: GET
            path: /api/{domain}/{project}/badges/security-score
        :   tags:
                deleted:
                    - security

The modified endpoints section has two items per key, method and path, this is called a complex mapping key in YAML.
Some YAML libraries don't support complex mapping keys:

• python PyYAML: see Tufin#94 (comment)
• golang gopkg.in/yaml.v3 fails to unmarshal the oasdiff output. This package offers a solution: https://github.com/tliron/yamlkeys

Breaking changes are changes that could break a client that is relying on the OpenAPI specification.
See some examples of breaking and non-breaking changes.
Note: this is a Beta feature. Please report issues.

Sometimes APIs need to be removed, for example, when we replace an old API by a new version. As API owners, we want a process that will allow us to phase out the old API version and transition to the new one smoothly as possible and with minimal disruptions to business.

OpenAPI specification supports a deprecated flag which can be used to mark operations and other object types as deprecated.
Normally, deprecation is not considered a breaking change since it doesn't break the client but only serves as an indication of an intent to remove something in the future, in contrast, the eventual removal of a resource is considered a breaking change.

oasdiff allows you to gracefully remove a resource without getting the breaking-change warning, as follows:

1. First, the resource is marked as deprecated and a special extension x-sunset is added to announce the date at which the resource will be removed

   /api/test:
    get:
     deprecated: true
     x-sunset: "2022-08-10"
   

2. At the sunset date or anytime later, the resource can be removed without triggering a breaking-change warning. An earlier removal will be considered a breaking change.

In addition, oasdiff also allows you to control the minimal number of days required between deprecating a resource and removing it with the deprecation-days flag.
For example, the following command requires any deprecation to be accompanied by an x-sunset extension with a date which is at least 30 days away, otherwise the deprecation itself will be considered a breaking change:

oasdiff -deprecation-days=30 -breaking-only -base data/deprecation/base.yaml -revision data/deprecation/deprecated-past.yaml

Setting deprecation-days to 0 is equivalent to the default which allows non-breaking deprecation regardless of the sunset date.
Note: this is a Beta feature. Please report issues.

Sometimes paths prefixes need to be modified, for example, to create a new version:

• /api/v1/...
• /api/v2/...

oasdiff allows comparison of API specifications with modified prefixes by stripping and/or prepending path prefixes.
In the example above you could compare the files as follows:

oasdiff -base original.yaml -revision new.yaml -strip-prefix-base /api/v1 -prefix-base /api/v2

or

oasdiff -base original.yaml -revision new.yaml -strip-prefix-base /api/v1 -strip-prefix-revision /api/v2

Note that stripping precedes prepending.

diff.Get(&diff.Config{}, spec1, spec2)

See full example: main.go

oasdiff expects OpenAPI References to be resolved.
References are normally resolved automatically when you load the spec. In other cases you can resolve refs using Loader.ResolveRefsIn.

Use configuration to exclude certain types of changes:

• Examples
• Descriptions
• Extensions are excluded by default

1. OpenAPI 3.1 support: see Tufin#52

If you have other ideas, please let us know.

This project relies on the excellent implementation of OpenAPI 3.0 for Go: kin-openapi