hc-install

An experimental Go module for downloading or locating HashiCorp binaries, verifying signatures and checksums, and asserting version constraints.

This module is a successor to tfinstall, available in pre-1.0 versions of terraform-exec. Current users of tfinstall are advised to move to hc-install before upgrading terraform-exec to v1.0.0.

hc-install is not a package manager

This library is intended for use within Go programs or automated environments (such as CIs) which have some business downloading or otherwise locating HashiCorp binaries.

The included command-line utility, hc-install, is a convenient way of using the library in ad-hoc or CI shell scripting outside of Go.

hc-install does not:

• Determine suitable installation path based on target system. e.g. in /usr/bin or /usr/local/bin on Unix based system.
• Deal with execution of installed binaries (via service files or otherwise).
• Upgrade existing binaries on your system.
• Add nor link downloaded binaries to your $PATH.

API

The Installer offers a few high-level methods:

• Ensure(context.Context, []src.Source) to find, install, or build a product version
• Install(context.Context, []src.Installable) to install a product version

Sources

The Installer methods accept number of different Source types. Each comes with different trade-offs described below.

• fs.{AnyVersion,ExactVersion} - Finds a binary in $PATH (or additional paths)
  • Pros:
    • This is most convenient when you already have the product installed on your system which you already manage.
  • Cons:
    • Only relies on a single version, expects you to manage the installation
    • Not recommended for any environment where product installation is not controlled or managed by you (e.g. default GitHub Actions image managed by GitHub)
• releases.{LatestVersion,ExactVersion} - Downloads, verifies & installs any known product from releases.hashicorp.com
  • Pros:
    • Fast and reliable way of obtaining any pre-built version of any product
  • Cons:
    • Installation may consume some bandwith, disk space and a little time
    • Potentially less stable builds (see checkpoint below)
• checkpoint.{LatestVersion} - Downloads, verifies & installs any known product available in HashiCorp Checkpoint
  • Pros:
    • Checkpoint typically contains only product versions considered stable
  • Cons:
    • Installation may consume some bandwith, disk space and a little time
    • Currently doesn't allow installation of a old versions (see releases above)
• build.{GitRevision} - Clones raw source code and builds the product from it
  • Pros:
    • Useful for catching bugs and incompatibilities as early as possible (prior to product release).
  • Cons:
    • Building from scratch can consume significant amount of time & resources (CPU, memory, bandwith, disk space)
    • There are no guarantees that build instructions will always be up-to-date
    • There's increased likelihood of build containing bugs prior to release
    • Any CI builds relying on this are likely to be fragile

Example Usage

Install single version

TODO

Find or install single version

i := NewInstaller()

v0_14_0 := version.Must(version.NewVersion("0.14.0"))

execPath, err := i.Ensure(context.Background(), []src.Source{
  &fs.ExactVersion{
    Product: product.Terraform,
    Version: v0_14_0,
  },
  &fs.AnyVersion{
    Product: &product.Terraform,
    Constraint: version.MustConstraints(version.NewConstraint("~> 0.14.0")),
  },
  &releases.ExactVersion{
    Product: product.Terraform,
    Version: v0_14_0,
  },
})
if err != nil {
  // process err
}

// run any tests

defer i.Remove()

Install multiple versions

TODO

Install and build multiple versions

i := NewInstaller()

vc, _ := version.NewConstraint(">= 0.12")
rv := &releases.Versions{
  Product:     product.Terraform,
  Constraints: vc,
}

versions, err := rv.List(context.Background())
if err != nil {
  return err
}
versions = append(versions, &build.GitRevision{Ref: "HEAD"})

for _, installableVersion := range versions {
  execPath, err := i.Ensure(context.Background(), []src.Source{
    installableVersion,
  })
  if err != nil {
    return err
  }

  // Do some testing here
  _ = execPath

  // clean up
  os.Remove(execPath)
}