GCP: Allow to select algo when generating temporary SSH keypair

[azr]

This is based on top of #10101, to solve the GCP case of #10074 this:

• adds temporary_key_pair_type/temporary_key_pair_bits option to the communicator.SSH struct
• makes the GCP builder use those options along with the sshkey Package to generate the correct temporary keypair when needed.
• updates GCP docs + generate all code

[codecov]

Codecov Report

Merging #10111 into master will decrease coverage by 0.03%.
The diff coverage is 0.00%.

Impacted Files	Coverage Δ
builder/googlecompute/builder.go	0.00% <0.00%> (ø)
helper/communicator/config.go	24.60% <ø> (ø)
helper/communicator/step_debug_ssh_keys.go	0.00% <0.00%> (ø)
helper/communicator/step_ssh_keygen.go	0.00% <0.00%> (ø)
helper/multistep/basic_runner.go	89.18% <0.00%> (-5.10%)	⬇️
helper/multistep/debug_runner.go	89.13% <0.00%> (-4.06%)	⬇️
helper/multistep/if.go	0.00% <0.00%> (ø)
...t-processor/googlecompute-export/post-processor.go	0.00% <0.00%> (ø)
... and 3 more

[SwampDragons]

ooooh shiny.

[SwampDragons]

Tried to run it and it crashed on me --

{
  "variables": {
      "image_name": "ubuntu1804-jenkins-{{isotime}}"
  },
  "builders": [
    {
      "type": "googlecompute",
      "image_name": "{{ user `image_name` | clean_resource_name}}",
      "account_file": "/myaccountfile.json",
      "project_id": "gifted-station-178619",
      "source_image_family": "ubuntu-1804-lts",
      "ssh_username": "packer",
      "zone": "us-central1-c",
      "state_timeout": "20m",
      "startup_script_file": "./shell_local_dummy.sh",
      "tags": ["packer"]
    }
  ],
  "provisioners": [
    {
      "pause_before": "10s",
      "type": "shell",
      "inline": ["echo {{ build `ID` }}"]
    }
  ]
}

[azr]

Thanks ! Weird, your file works on my machine 🤔 any special options ? Do you have the crash log ?

[azr]

NVM found it !

[azr]

Here's a testfile that works with any value:

{
    "builders": [
        {
            "type": "googlecompute",
            "project_id": "azr-hashicorp",
            "image_name": "base-centos-7-{{timestamp}}",
            "source_image": "centos-7-v20200521",
            "source_image_family": "centos-7",
            "ssh_username": "centos",
            "temporary_key_pair_type": "ecdsa",
            "temporary_key_pair_bits": 521,
            "zone": "europe-west2-a",
            "machine_type": "n1-standard-1",
            "disk_size": 20,
            "enable_secure_boot": true,
            "enable_vtpm": true,
            "enable_integrity_monitoring": true
        }
    ],
    "provisioners": [
        {
            "destination": "/tmp/hm hi,\\ I have a space \u0026 ☺",
            "source": "log.go",
            "type": "file"
        }
    ],
    "variables": {
        "zone": "europe-west4-a"
    }
}

Edit: HCL2 is not 100%, I'm on it.

[azr]

Here's a cool HCL2 test file, ( you need a log.go file there ):

variable "zone" {
  type    = string
  default = "europe-west4-a"
}

source "googlecompute" "centos" {
  disk_size                   = 20
  enable_integrity_monitoring = true
  enable_secure_boot          = true
  enable_vtpm                 = true
  machine_type                = "n1-standard-1"
  project_id                  = "azr-hashicorp"
  source_image                = "centos-7-v20200521"
  source_image_family         = "centos-7"
  ssh_username                = "centos"
  zone                        = "europe-west2-a"
}

build {
  source "googlecompute.centos" {
    temporary_key_pair_type = "dsa"
    image_name              = "base-centos-7-dsa"
  }
  source "googlecompute.centos" {
    temporary_key_pair_type = "rsa"
    image_name              = "base-centos-7-rsa"
  }
  source "googlecompute.centos" {
    temporary_key_pair_type = "ecdsa"
    image_name              = "base-centos-7-ecdsa"
  }
  source "googlecompute.centos" {
    temporary_key_pair_type = "ed25519"
    image_name              = "base-centos-7-ed25519"
  }

  provisioner "file" {
    destination = "/tmp/hm hi,\\ I have a space & ☺"
    source      = "log.go"
  }
}

[SwampDragons]

cool! Your example works, but my original example still doesn't, and it does work on the master branch so we need to make sure that the default case still works.

[azr]

Ah indeed ! Thanks !

[azr]

Okay found the why, with no parameter this changed the default keytype from rsa to dsa ( because this was the default for ssh-keygen too and I thought this was the safest approach and that it would not break anything), this is clearly a breaking change so I'm making the default type rsa for backwards compat.

[nywilken]

This looks great. Lots of nice little add-ons here. I have not tested against the examples but code wise it looks good. I approve, but will defer until @SwampDragons has given the green light that their use case has been satisfied.

[nywilken]

Nice

[SwampDragons]

yep, works now!

[ghost]

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