Interpolation does not work with artifact checksums

[matthoey-okta]

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Nomad version

Output from nomad version
Nomad v0.8.4 (dbee1d7)

Operating system and Environment details

Amazon Linux 1 2018.03.1

Issue

I looked at the release notes and didn't see this so I don't think it's my version.

When trying to use a meta variable and interpolation for a checksum of an artifact it fails out with an error message:

* Artifact 1 validation failed: 1 error(s) occurred:

* invalid checksum: encoding/hex: invalid byte: U+0024 '$'
* Artifact 2 validation failed: 1 error(s) occurred:

* invalid checksum: encoding/hex: invalid byte: U+0024 '$')

I originally had md5:${NOMAD_META_ARTIFACT_MD5} but also tried putting the md5: in the variable to no success.

Reproduction steps

Attempt to use interpolation in the checksum of an artifact
Run nomad job plan on your job file.

Nomad Server logs (if appropriate)

Nomad Client logs (if appropriate)

Job file (if appropriate)

[dadgar]

Good catch. Issue is that we are checking for the length pre-interpolation: https://github.com/hashicorp/nomad/blob/master/nomad/structs/structs.go#L6143-L6182

We will have to lower the level of validation we provide if there is an interpolation since on the server we may not have all possible values to interpolate with.

[matthoey-okta]

Thanks!

[github-actions]

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