Key generation in Pact V4 interactions is unstable across multiple runs

[mefellows]

Issue originally reported here: https://github.com/pact-foundation/pact-go/issues/230

Repro here: https://github.com/pact-foundation/pact-reference/blob/repro/pact-go-issue-230/rust/pact_consumer/tests/tests.rs#L24

Run the test several times, you should observe the key for the only interaction change between 7a7816368c8f4344 and e659df3a695ccd82.

file rust/pact_consumer/target/pact_dir/Consumer-Alice Service.json:

{
  "consumer": {
    "name": "Consumer"
  },
  "interactions": [
    {
      "description": "a retrieve Mallory request",
      "key": "7a7816368c8f4344",
      "pending": false,
      "providerStates": [
        {
          "name": "there is some good mallory"
        }
      ],
      "request": {
        "headers": {
          "content-type": [
            "application/json"
          ]
        },
        "method": "GET",
        "path": "/mallory"
      },
      "response": {
        "body": {
          "content": "That is some good Mallory.",
          "contentType": "*/*",
          "encoded": false
        },
        "headers": {
          "Content-Type": [
            "text/plain"
          ]
        },
        "status": 200
      },
      "transport": "http",
      "type": "Synchronous/HTTP"
    }
  ],
  "metadata": {
    "pactRust": {
      "consumer": "0.10.4",
      "mockserver": "0.9.8",
      "models": "1.0.4"
    },
    "pactSpecification": {
      "version": "4.0"
    }
  },
  "provider": {
    "name": "Alice Service"
  }
}

and

{
  "consumer": {
    "name": "Consumer"
  },
  "interactions": [
    {
      "description": "a retrieve Mallory request",
      "key": "e659df3a695ccd82",
      "pending": false,
      "providerStates": [
        {
          "name": "there is some good mallory"
        }
      ],
      "request": {
        "headers": {
          "content-type": [
            "application/json"
          ]
        },
        "method": "GET",
        "path": "/mallory"
      },
      "response": {
        "body": {
          "content": "That is some good Mallory.",
          "contentType": "*/*",
          "encoded": false
        },
        "headers": {
          "Content-Type": [
            "text/plain"
          ]
        },
        "status": 200
      },
      "transport": "http",
      "type": "Synchronous/HTTP"
    }
  ],
  "metadata": {
    "pactRust": {
      "consumer": "0.10.4",
      "mockserver": "0.9.8",
      "models": "1.0.4"
    },
    "pactSpecification": {
      "version": "4.0"
    }
  },
  "provider": {
    "name": "Alice Service"
  }
}

As per the original ticket, I suspect it's something to do with the request part of the interaction.

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[rholshausen]

I was not able to reproduce this, the key is always 375d0fac416d80f2 when I run that test.

This may be an MacOS specific issue. I will test on Windows to see what the behavior is there.

[rholshausen]

Running on Windows, the key is the same as on Linux.

[rholshausen]

Ok, managed to replicate the issue, it's when the header is added to the request (which is a bit silly on a GET)

[mefellows]

Is it just the content-type header or any header (e.g. accept?)

In the Go example I had, it's a POST request (I'll test locally now). I could also reproduce the problem (in Go at least) with a request body also.

[rholshausen]

I haven't diagnosed the issue yet, but I'm willing to bet it is due to ordering of keys in the header hashmap.

[mefellows]

Ahh yeah, that makes sense. I thought I recalled seeing a procedure that ordered the headers before hashing, so perhaps there is a bug in that. That could also explain why the body does it, because it would implicitly set a content-type header too.

FYI here is a quick recording of me doing it on a POST.

https://user-images.githubusercontent.com/53900/231636671-090ff76e-1f40-4163-9b74-fe6f0de3ef24.mov

[rholshausen]

Oh, lookie here

[mefellows]

That's interesting. I'm not seeing that change locally, only the key.

Are you suggesting that because the test has content-type rather than Content-Type one is taking precedence over the other?

[rholshausen]

I don't know why it is happening, but that diff shows the point at which the key is calculated, and it is showing how those two key values are being generated. I.e. the key generation is deterministic. My suspicion is when the mock server writes the Pact file, the merge is causing this.

I'm going to update the hash function to always generate the same key regardless of the case of the header keys, which will fix the issue. But there is still a question as to why it is happening in the first place.

[mefellows]

Ah, ok that makes some form of sense.

[rholshausen]

I've gone through all the hash functions on all the models, hopefully it should now not change if the JSON doesn't change. I've also updated it so things like different case HTTP methods will still generate the same key.

[mefellows]

Awesome, thanks. I've just pulled this locally, compiled and tested with go - looks like the issue is resolved.

I did notice a bunch of dbg! statements still hanging around though:

    id: None,
    key: None,
    description: "some interaction",
    provider_states: [],
    request: HttpRequest {
        method: "POST",
        path: "/products",
        query: None,
        headers: Some(
            {
                "content-type": [
                    "application/json",
                ],
            },
        ),
        body: Missing,
        matching_rules: MatchingRules {
            rules: {
                PATH: MatchingRuleCategory {
                    name: PATH,
                    rules: {},
                },
                HEADER: MatchingRuleCategory {
                    name: HEADER,
                    rules: {},
                },
            },
        },
        generators: Generators {
            categories: {},
        },
    },
    response: HttpResponse {
        status: 200,
        headers: None,
        body: Missing,
        matching_rules: MatchingRules {
            rules: {},
        },
        generators: Generators {
            categories: {},
        },
    },
    comments: {},
    pending: false,
    plugin_config: {},
    interaction_markup: InteractionMarkup {
        markup: "",
        markup_type: "",
    },
    transport: Some(
        "http",
    ),
}

[rholshausen]

I did notice a bunch of dbg! statements still hanging around though:

Gah! It burns us, it burns us!

[adamrodger]

@uglyog @mefellows This is still broken for me in FFI 0.4.4 on this pact file:

{
  "consumer": {
    "name": "PactExtensionsTests-Consumer-V4"
  },
  "interactions": [
    {
      "description": "a sample request",
      "key": "e037db1f569db957",
      "pending": false,
      "providerStates": [
        {
          "name": "a provider state"
        },
        {
          "name": "another provider state"
        },
        {
          "name": "a provider state with params",
          "params": {
            "baz": "bash",
            "foo": "bar"
          }
        }
      ],
      "request": {
        "body": {
          "content": {
            "bool": true,
            "children": [
              {
                "bool": false,
                "int": 7,
                "string": "bar"
              }
            ],
            "int": 42,
            "string": "foo"
          },
          "contentType": "application/json",
          "encoded": false
        },
        "headers": {
          "Content-Type": [
            "application/json"
          ],
          "X-Request": [
            "request1",
            "request2"
          ]
        },
        "matchingRules": {
          "body": {
            "$.bool": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            },
            "$.children": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type",
                  "min": 1
                }
              ]
            },
            "$.children[*].bool": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            },
            "$.children[*].int": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            },
            "$.children[*].string": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            },
            "$.int": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            },
            "$.string": {
              "combine": "AND",
              "matchers": [
                {
                  "match": "type"
                }
              ]
            }
          },
          "header": {},
          "query": {}
        },
        "method": "POST",
        "path": "/things",
        "query": {
          "param": [
            "value1",
            "value2"
          ]
        }
      },
      "response": {
        "body": {
          "content": {
            "bool": true,
            "children": [
              {
                "bool": false,
                "int": 7,
                "string": "bar"
              }
            ],
            "int": 42,
            "string": "foo"
          },
          "contentType": "application/json",
          "encoded": false
        },
        "headers": {
          "Content-Type": [
            "application/json"
          ],
          "X-Response": [
            "response1",
            "response2"
          ]
        },
        "status": 201
      },
      "type": "Synchronous/HTTP"
    }
  ],
  "metadata": {
    "pactRust": {
      "ffi": "0.4.4",
      "models": "1.0.13"
    },
    "pactSpecification": {
      "version": "4.0"
    }
  },
  "provider": {
    "name": "PactExtensionsTests-Provider"
  }
}

The key flips between e037db1f569db957 and 917ca8ce1f6b5279 on subsequent runs

[adamrodger]

All of the data is hard-coded in that tests btw. The JSON of the interactions itself doesn't change, just the key.

[mefellows]

Looks like a few more games of whack-a-mole are going to be required here.

[adamrodger]

I've got a message interaction doing it as well (just in case we thought it was HTTP only):

{
  "consumer": {
    "name": "PactExtensionsTests-MessageConsumer-V4"
  },
  "interactions": [
    {
      "contents": {
        "content": {
          "bool": false,
          "int": 1,
          "string": "a description"
        },
        "contentType": "application/json",
        "encoded": false
      },
      "description": "a sample request",
      "key": "fdb9aa53df5e5d7",
      "metadata": {
        "queueId": "1234"
      },
      "pending": false,
      "providerStates": [
        {
          "name": "a provider state"
        },
        {
          "name": "another provider state"
        },
        {
          "name": "a provider state with params",
          "params": {
            "baz": "bash",
            "foo": "bar"
          }
        }
      ],
      "type": "Asynchronous/Messages"
    }
  ],
  "metadata": {
    "framework": {
      "language": "C#"
    },
    "pactRust": {
      "ffi": "0.4.4",
      "models": "1.0.13"
    },
    "pactSpecification": {
      "version": "4.0"
    }
  },
  "provider": {
    "name": "PactExtensionsTests-MessageProvider"
  }
}

[mefellows]

Thanks! What jumps out to me there are the multiple provider states, perhaps the internal array representation is messing with it 🤷 . Or

[adamrodger]

Yeah and one of the provider states has multiple values also - that seems suspicious straight away

[rholshausen]

I'm going to remove the key generation, it is causing too may issues. This was meant to be a user supplied key (See https://github.com/pact-foundation/pact-specification/issues/72) and the idea was to auto-calculate it if it was not supplied by a user.

[nsfrias]

I also experiencing this issue right now (Pact-go CLI v2.0.0-beta.18).

I am happy to test any fix with my tests, when one is available.

It would also be great if Pact-go can be updated to pull the ffi version with the fix.

[mefellows]

Thanks @nsfrias. I'll push out an intermediate version which resolved the example I had above, if that helps. In the meantime, Ron has proposed to revert that change which would eventually fully resolve it.

[nsfrias]

I don't know what is the use case behind the key value. That said from my perspective reverting the change would be the best.

[mefellows]

The next FFI release should have the auto-generated keys removed. Once this is out we can address upstream issues (e.g. https://github.com/pact-foundation/pact-go/issues/230)

[mefellows]

Closing as the fix has been applied, however there is a related issue #278 that needs addressing for plugins.