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https://github.com/priyanshujain/sanderling.git
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pj
6a9fac7ec0
Ships with a 24-byte placeholder so fresh clones build without requiring a sidecar build first. `make uatu` copies the real fat JAR into internal/sidecar/assets before `go build`, so shipping binaries carry the full sidecar (~130 MB). Extract writes the JAR to a temp dir alongside a SHA-256 file and skips rewrite when the checksum already matches.
65 lines
1.9 KiB
Go
65 lines
1.9 KiB
Go
package sidecar
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import (
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"crypto/sha256"
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"encoding/hex"
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_ "embed"
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"errors"
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"fmt"
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"os"
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"path/filepath"
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)
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//go:embed assets/sidecar-all.jar
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var embeddedJAR []byte
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// PlaceholderMagic is the byte sequence written to the placeholder JAR that
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// ships in the repository. A binary that still carries the placeholder is
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// not runnable against a real sidecar — `make sidecar && make uatu` must
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// have been invoked to embed the real fat JAR.
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const PlaceholderMagic = "uatu-sidecar-placeholder"
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// IsPlaceholder reports whether the embedded JAR is the development
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// placeholder rather than a real sidecar fat JAR.
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func IsPlaceholder() bool {
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return string(embeddedJAR) == PlaceholderMagic
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}
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// EmbeddedSize returns the size in bytes of the embedded JAR.
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func EmbeddedSize() int { return len(embeddedJAR) }
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// EmbeddedSHA256 returns the hex-encoded SHA-256 of the embedded JAR.
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func EmbeddedSHA256() string {
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sum := sha256.Sum256(embeddedJAR)
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return hex.EncodeToString(sum[:])
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}
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// Extract writes the embedded JAR to a deterministic path inside dir,
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// alongside a .sha256 file. If the destination already exists with a
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// matching checksum, no rewrite happens. Returns the JAR path.
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func Extract(dir string) (string, error) {
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if len(embeddedJAR) == 0 {
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return "", errors.New("sidecar: embedded JAR is empty")
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}
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if err := os.MkdirAll(dir, 0o755); err != nil {
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return "", fmt.Errorf("mkdir %s: %w", dir, err)
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}
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jarPath := filepath.Join(dir, "uatu-sidecar.jar")
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checksumPath := jarPath + ".sha256"
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checksum := EmbeddedSHA256()
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if existing, err := os.ReadFile(checksumPath); err == nil && string(existing) == checksum {
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if _, err := os.Stat(jarPath); err == nil {
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return jarPath, nil
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}
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}
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if err := os.WriteFile(jarPath, embeddedJAR, 0o644); err != nil {
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return "", fmt.Errorf("write %s: %w", jarPath, err)
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}
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if err := os.WriteFile(checksumPath, []byte(checksum), 0o644); err != nil {
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return "", fmt.Errorf("write checksum: %w", err)
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}
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return jarPath, nil
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}
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