mesh-controller/internal/inventory/builds.go

package inventory

import (
	"context"
	"encoding/json"
	"time"
)

// What has been built.
//
// A build result was answered to whoever asked and kept nowhere, so "when did this last build",
// "why did it fail" and "which machine built what is running" had no answer. Failures are recorded
// too: one that leaves no trace is indistinguishable from a build nobody asked for, and the
// difference is the whole of whether somebody should be looking at something.

// Build is one attempt, whichever way it went.
type Build struct {
	ID         string
	Repository string
	Ref        string
	// Module is empty for a build that failed before it knew what it was building.
	Module string
	Commit string
	// On is the machine that did it.
	On string
	// Failed is the builder's own words, empty when it worked.
	Failed string
	Made   []Artifact
	At     time.Time
}

// Artifact is one thing a build published.
type Artifact struct {
	Name      string `json:"name"`
	Kind      string `json:"kind"`
	Reference string `json:"reference"`
}

// Worked reports whether this build produced something.
func (b Build) Worked() bool { return b.Failed == "" }

// RecordBuild keeps what a builder said.
//
// Idempotent on the correlation id, because a result can arrive twice: once as the answer to
// whoever asked and once on the exchange when nobody was. Recording both would show one build as
// two, and which of the two is real is not a question anybody could answer afterwards.
func (i *Inventory) RecordBuild(ctx context.Context, b Build) error {
	made, err := json.Marshal(b.Made)
	if err != nil {
		return err
	}
	var module *string
	if b.Module != "" {
		module = &b.Module
	}
	_, err = i.store.Pool().Exec(ctx,
		`insert into build (id, repository, ref, module, commit_hash, built_on, failed, made)
		 values ($1, $2, $3, $4, $5, $6, $7, $8)
		 on conflict (id) do nothing`,
		b.ID, b.Repository, b.Ref, module, b.Commit, b.On, b.Failed, made)
	return err
}

// Builds is what has happened lately, newest first.
//
// For one module when named, or across the mesh when not. Both are asked: *what happened just
// now* after something goes wrong, and *what has happened to this* when deciding whether to
// trust it.
func (i *Inventory) Builds(ctx context.Context, module string, limit int) ([]Build, error) {
	if limit <= 0 {
		limit = 20
	}
	query := `select id, repository, ref, coalesce(module,''), commit_hash, built_on, failed, made, at
	          from build order by at desc limit $1`
	args := []any{limit}
	if module != "" {
		query = `select id, repository, ref, coalesce(module,''), commit_hash, built_on, failed, made, at
		         from build where module = $2 order by at desc limit $1`
		args = append(args, module)
	}

	rows, err := i.store.Pool().Query(ctx, query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []Build
	for rows.Next() {
		var b Build
		var made []byte
		if err := rows.Scan(&b.ID, &b.Repository, &b.Ref, &b.Module, &b.Commit,
			&b.On, &b.Failed, &made, &b.At); err != nil {
			return nil, err
		}
		if err := json.Unmarshal(made, &b.Made); err != nil {
			return nil, err
		}
		out = append(out, b)
	}
	return out, rows.Err()
}

// Held is every artifact this mesh has built, keyed "<module>/<artifact>".
//
// **The newest successful build of each module wins**, which is the same rule the rest of the mesh
// uses for what a module currently is. A module rebuilt to something broken and then rebuilt again
// is at the second one; a module whose last build failed is at the last one that worked, because a
// failure published nothing and the thing it published before is still what exists.
//
// Only successes, and only builds that knew what they were building: a build that failed before it
// could read a manifest has no module to be the artifact of.
func (i *Inventory) Held(ctx context.Context) (map[string]string, error) {
	rows, err := i.store.Pool().Query(ctx,
		`select distinct on (module) module, made
		   from build
		  where module is not null and module <> '' and failed = ''
		  order by module, at desc`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	held := map[string]string{}
	for rows.Next() {
		var module string
		var raw []byte
		if err := rows.Scan(&module, &raw); err != nil {
			return nil, err
		}
		var made []Artifact
		if err := json.Unmarshal(raw, &made); err != nil {
			// Skipped rather than fatal. One unreadable build record should not stop every other
			// module's base from being answerable — and the build that needs this one will say
			// plainly that it is missing.
			continue
		}
		for _, artifact := range made {
			if artifact.Name == "" || artifact.Reference == "" {
				continue
			}
			held[module+"/"+artifact.Name] = artifact.Reference
		}
	}
	return held, rows.Err()
}