CONTRIBUTING.md

Thanks for helping us build Boulder! This page contains requirements and guidelines for Boulder contributions.

Patch Requirements

• All new functionality and fixed bugs must be accompanied by tests.
• All patches must meet the deployability requirements listed below.
• We prefer pull requests from external forks be created with the "Allow edits from maintainers" checkbox selected.

Review Requirements

• All pull requests must receive at least one approval through the GitHub UI.
• We indicate review approval through GitHub's code review facility.
• New commits pushed to a branch invalidate previous reviews. In other words, a reviewer must give positive reviews of a branch after its most recent pushed commit.
• You cannot review your own code.
• If a branch contains commits from multiple authors, it needs a reviewer who is not an author of commits on that branch.
• If a branch contains updates to files in the vendor/ directory, the author is responsible for running tests in all updated dependencies, and commenting in the review thread that they have done so. Reviewers must not approve reviews that have changes in vendor/ but lack a comment about tests.
• Review changes to or addition of tests just as rigorously as you review code changes. Consider: Do tests actually test what they mean to test? Is this the best way to test the functionality in question? Do the tests cover all the functionality in the patch, including error cases?
• Are there new RPCs or config fields? Make sure the patch meets the Deployability rules below.

Patch Guidelines

• Please include helpful comments. No need to gratuitously comment clear code, but make sure it's clear why things are being done. Include information in your pull request about what you're trying to accomplish with your patch.

• Avoid named return values. See #3017 for an example of a subtle problem they can cause.

• Do not include XXXs or naked TODOs. Use the formats:

  // TODO(<email-address>): Hoverboard + Time-machine unsupported until upstream patch.
  // TODO(#<num>): Pending hoverboard/time-machine interface.
  // TODO(@githubusername): Enable hoverboard kickflips once interface is stable.

Squash merging

Once a pull request is approved and the tests are passing, the author or any other committer can merge it. We always use squash merges via GitHub's web interface. That means that during the course of your review you should generally not squash or amend commits, or force push. Even if the changes in each commit are small, keeping them separate makes it easier for us to review incremental changes to a pull request. Rest assured that those tiny changes will get squashed into a nice meaningful-size commit when we merge.

If the CI tests are failing on your branch, you should look at the logs to figure out why. Sometimes (though rarely) they fail spuriously, in which case you can post a comment requesting that a project owner kick the build.

Error handling

All errors must be addressed in some way: That may be simply by returning an error up the stack, or by handling it in some intelligent way where it is generated, or by explicitly ignoring it and assigning to _. We use the errcheck tool in our integration tests to make sure all errors are addressed. Note that ignoring errors, even in tests, should be rare, since they may generate hard-to-debug problems.

We define two special types of error. BoulderError, defined in errors/errors.go, is used specifically when an typed error needs to be passed across an RPC boundary. For instance, if the SA returns "not found", callers need to be able to distinguish that from a network error. Not every error that may pass across an RPC boundary needs to be a BoulderError, only those errors that need to be handled by type elsewhere. Handling by type may be as simple as turning a BoulderError into a specific type of ProblemDetail.

The other special type of error is ProblemDetails. We try to treat these as a presentation-layer detail, and use them only in parts of the system that are responsible for rendering errors to end-users, i.e. wfe and wfe2. Note one exception: The VA RPC layer defines its own ProblemDetails type, which is returned to the RA and stored as part of a challenge (to eventually be rendered to the user).

Within WFE and WFE2, ProblemDetails are sent to the client by calling sendError(), which also logs the error. For internal errors like timeout, or any error type that we haven't specifically turned into a ProblemDetail, we return a ServerInternal error. This avoids unnecessarily exposing internals. It's possible to add additional errors to a logEvent using .AddError(), but this should only be done when there is is internal-only information to log that isn't redundant with the ProblemDetails sent to the user. Note that the final argument to sendError(), ierr, will automatically get added to the logEvent for ServerInternal errors, so when sending a ServerInternal error it's not necessary to separately call .AddError.

Deployability

We want to ensure that a new Boulder revision can be deployed to the currently running Boulder production instance without requiring config changes first. We also want to ensure that during a deploy, services can be restarted in any order. That means two things:

Good zero values for config fields

Any newly added config field must have a usable zero value. That is to say, if a config field is absent, Boulder shouldn't crash or misbehave. If that config file names a file to be read, Boulder should be able to proceed without that file being read.

Note that there are some config fields that we want to be a hard requirement. To handle such a field, first add it as optional, then file an issue to make it required after the next deploy is complete.

In general, we would like our deploy process to be: deploy new code + old config; then immediately after deploy the same code + new config. This makes deploys cheaper so we can do them more often, and allows us to more readily separate deploy-triggered problems from config-triggered problems.

Flag-gating features

When adding significant new features or replacing existing RPCs the boulder/features package should be used to gate its usage. To add a flag a new const FeatureFlag should be added and its default value specified in features.features in features/features.go. In order to test if the flag is enabled elsewhere in the codebase you can use features.Enabled(features.ExampleFeatureName) which returns a bool indicating if the flag is enabled or not.

Each service should include a map[string]bool named Features in its configuration object at the top level and call features.Set with that map immediately after parsing the configuration. For example to enable UseNewMetrics and disable AccountRevocation you would add this object:

{
    ...
    "features": {
        "UseNewMetrics": true,
        "AccountRevocation": false,
    }
}

Feature flags are meant to be used temporarily and should not be used for permanent boolean configuration options. Once a feature has been enabled in both staging and production the flag should be removed making the previously gated functionality the default in future deployments.

Gating RPCs

When you add a new RPC to a Boulder service (e.g. SA.GetFoo()), all components that call that RPC should gate those calls using a feature flag. Since the feature's zero value is false, a deploy with the existing config will not call SA.GetFoo(). Then, once the deploy is complete and we know that all SA instances support the GetFoo() RPC, we do a followup config deploy that sets the default value to true, and finally remove the flag entirely once we are confident the functionality it gates behaves correctly.

Gating migrations

We use database migrations to modify the existing schema. These migrations will be run on live data while Boulder is still running, so we need Boulder code at any given commit to be capable of running without depending on any changes in schemas that have not yet been applied.

For instance, if we're adding a new column to an existing table, Boulder should run correctly in three states:

1. Migration not yet applied.
2. Migration applied, flag not yet flipped.
3. Migration applied, flag flipped.

Specifically, that means that all of our SELECT statements should enumerate columns to select, and not use *. Also, generally speaking, we will need a separate model struct for serializing and deserializing data before and after the migration. This is because the ORM package we use, gorp, expects every field in a struct to map to a column in the table. If we add a new field to a model struct and Boulder attempts to write that struct to a table that doesn't yet have the corresponding column (case 1), gorp will fail with Insert failed table posts has no column named Foo. There are examples of such models in sa/model.go, along with code to turn a model into a struct used internally.

An example of a flag-gated migration, adding a new IsWizard field to Person controlled by a AllowWizards feature flag:

# features/features.go:

const (
  unused FeatureFlag = iota // unused is used for testing
  AllowWizards // Added!
)

...

var features = map[FeatureFlag]bool{
  unused: false,
  AllowWizards: false, // Added!
}

# sa/sa.go:

struct Person {
  HatSize  int
  IsWizard bool // Added!
}

struct personModelv1 {
  HatSize int
}

// Added!
struct personModelv2 {
  personModelv1
  IsWizard bool
}

func (ssa *SQLStorageAuthority) GetPerson() (Person, error) {
  if features.Enabled(features.AllowWizards) { // Added!
    var model personModelv2
    ssa.dbMap.SelectOne(&model, "SELECT hatSize, isWizard FROM people")
    return Person{
      HatSize:  model.HatSize,
      IsWizard: model.IsWizard,
    }
  } else {
    var model personModelv1
    ssa.dbMap.SelectOne(&model, "SELECT hatSize FROM people")
    return Person{
      HatSize:  model.HatSize,
    }
  }
}

func (ssa *SQLStorageAuthority) AddPerson(p Person) (error) {
  if features.Enabled(features.AllowWizards) { // Added!
    return ssa.dbMap.Insert(personModelv2{
      personModelv1: {
        HatSize:  p.HatSize,
      },
      IsWizard: p.IsWizard,
    })
  } else {
    return ssa.dbMap.Insert(personModelv1{
      HatSize:  p.HatSize,
      // p.IsWizard ignored
    })
  }
}

You will also need to update the initTables function from sa/database.go to tell Gorp which table to use for your versioned model structs. Make sure to consult the flag you defined so that only one of the table maps is added at any given time, otherwise Gorp will error. Depending on your table you may also need to add SetKeys and SetVersionCol entries for your versioned models. Example:

func initTables(dbMap *gorp.DbMap) {
 // < unrelated lines snipped for brevity >

 if features.Enabled(features.AllowWizards) {
    dbMap.AddTableWithName(personModelv2, "person")
 } else {
    dbMap.AddTableWithName(personModelv1, "person")
 }
}

You can then add a migration with:

$ goose -path ./sa/_db/ create AddWizards sql

Finally, edit the resulting file (sa/_db/migrations/20160915101011_AddWizards.sql) to define your migration:

-- +goose Up
ALTER TABLE people ADD isWizard BOOLEAN SET DEFAULT false;

-- +goose Down
ALTER TABLE people DROP isWizard BOOLEAN SET DEFAULT false;

Release Process

The current Boulder release process is described in the boulder release process repository. It includes an example git history showing a regular release being tagged, a hotfix being tagged from a clean main, and a hotfix being tagged from a release branch because main was dirty.

Previously we used dedicated staging and release branches. This had several downsides and we frequently forgot to merge staging to release once code had been shipped to production. We do not use the staging and release branches anymore. Releases tagged from prior to Feb 1st 2017 are also outdated artifacts of old process (e.g. the hotfixes-2017-02-01 tag).

Dependencies

We use go modules and vendor our dependencies. As of Go 1.12, this may require setting the GO111MODULE=on and GOFLAGS=-mod=vendor environment variables. Inside the Docker containers for Boulder tests, these variables are set for you, but if you ever work outside those containers you will want to set them yourself.

To add a dependency, add the import statement to your .go file, then run go build on it. This will automatically add the dependency to go.mod. Next, run go mod vendor && git add vendor/ to save a copy in the vendor folder.

When vendorizing dependencies, it's important to make sure tests pass on the version you are vendorizing. Currently we enforce this by requiring that pull requests containing a dependency update to any version other than a tagged release include a comment indicating that you ran the tests and that they succeeded, preferably with the command line you run them with. Note that you may have to get a separate checkout of the dependency (using go get outside of the boulder repository) in order to run its tests, as some vendored modules do not bring their tests with them.

Updating Dependencies

To upgrade a dependency, see the Go docs. Typically you want go get <dependency> rather than go get -u <dependency>, which can introduce a lot of unexpected updates. After running go get, make sure to run go mod vendor && git add vendor/ to update the vendor directory. If you forget, CI tests will catch this.

If you are updating a dependency to a version which is not a tagged release, see the note above about how to run all of a dependency's tests and note that you have done so in the PR.

Note that updating dependencies can introduce new, transitive dependencies. In general we try to keep our dependencies as narrow as possible in order to minimize the number of people and organizations whose code we need to trust. As a rule of thumb: If an update introduces new packages or modules that are inside a repository where we already depend on other packages or modules, it's not a big deal. If it introduces a new dependency in a different repository, please try to figure out where that dependency came from and why (for instance: "package X, which we depend on, started supporting XML config files, so now we depend on an XML parser") and include that in the PR description. When there are a large number of new dependencies introduced, and we don't need the functionality they provide, we should consider asking the relevant upstream repository for a refactoring to reduce the number of transitive dependencies.

Go Version

The Boulder development environment does not use the Go version installed on the host machine, and instead uses a Go environment baked into a "boulder-tools" Docker image. We build a separate boulder-tools container for each supported Go version. Please see the Boulder-tools README for more information on upgrading Go versions.

ACME Protocol Divergences

While Boulder attempts to implement the ACME specification as strictly as possible there are places at which we will diverge from the letter of the specification for various reasons. We detail these divergences (for both the V1 and V2 API) in the ACME divergences doc.

ACME Protocol Implementation Details

The ACME specification allows developers to make certain decisions as to how various elements in the RFC are implemented. Some of these fully conformant decisions are listed in ACME implementation details doc.

Problems or questions?

The best place to ask dev related questions is on the Community Forums.