Additional template variables

[heidemn]

The following variables would be useful if available in templates, so that all relevant information is available for archival of the results.

• Timestamp
• Trivy version
• Image tag (currently not available separately, without the OS)
• Image hash (since the tag might refer to a different image later)

For batch scanning and generating a consolidated view of multiple images, it would also be helpful to use the template for errors.
Internal errors (DB not readable) could still return an error code, but errors like "OS not supported" could use the template and maybe return exit code 0.

Possible extension:
Unfortunately, this change would be downwards-incompatible.
"Targets" is equal to the current output of v0.4.2.

{
  "StartedAt": "2020-01-22T00:39:57Z",
  "TrivyVersion": "0.4.2",
  "ImageTag": "repo.org/image:1.2.3",
  "ImageHash": "sha256:8d31dad0c58f552e890d68bbfb735588b6b820a46e459672d96e585871acc110",
  "Error": null,
  "Targets": [
    {
      "Target": "repo.org/image:1.2.3 (ubuntu 18.04)",
      "Vulnerabilities": [
        {
          "VulnerabilityID": "CVE-2019-13627",
          "PkgName": "libgcrypt20",
          "InstalledVersion": "1.8.1-4ubuntu1.1",
          "FixedVersion": "1.8.1-4ubuntu1.2",
          "Title": "libgcrypt: ECDSA timing attack in the libgcrypt20 cryptographic library",
          "Description": "It was discovered ..",
          "Severity": "MEDIUM",
          "References": [ "url", "url, ... ]
        }
      ]
    }
  ]
}

Error case:

{
  "StartedAt": "2020-01-22T00:39:57Z",
  "TrivyVersion": "0.4.2",
  "ImageTag": "repo.org/image:1.2.3",
  "ImageHash": "sha256:8d31dad0c58f552e890d68bbfb735588b6b820a46e459672d96e585871acc110",
  "Error": "OS not supported",
  "Targets": null
}

[mrueg]

See also: #332

[heidemn]

@mrueg thanks, I had missed that one. Added a suggestion there.

[jeff-cook]

It would also be nice to have the database version or date.