"Failed to read seal configuration" errors after upgrading to 0.10.2

[mjacksonw]

Describe the bug
After upgrading from 0.10.1 (or 0.10.0) to 0.10.2, vault produces the following errors:

[ERROR] core: failed to read seal configuration: error="UnmarshalTypeError: cannot unmarshal string into Go value of type []uint8"
[INFO ] core: security barrier not initialized 

Environment:

• Vault Server Version (retrieve with vault status): 0.10.2
• Vault CLI Version (retrieve with vault version): 0.10.2
• Server Operating System/Architecture: Alpine Linux 3.6 / Docker

Vault server configuration file(s):

listener "tcp" {
  address     = "0.0.0.0:8200"
  tls_disable = "true"
  proxy_protocol_behavior = "use_always"
  proxy_protocol_authorized_addrs = "REDACTED"
}

storage "dynamodb" {
  ha_enabled      = "true"
  region          = "us-east-1"
  table           = "REDACTED"
  advertise_addr  = "REDACTED"
  recovery_mode   = 1
}

disable_mlock = "true"
ui = "true"

[jefferai]

Can you build a branch if I put in some debug?

[mjacksonw]

I can give it a try! Also, I just spun up a local version of 0.10.2 (on MacOS, against the same dynamodb table) and got the same error, so it's not likely related to the environment.

[mjacksonw]

Yup, got a build env going, and confirmed I get the same issue against master (which is likely unsurprising).

[mjacksonw]

Did a git bisect against the diff between 0.10.1 and 0.10.2 and came up against this seemingly-relevant commit:

39f2d66

[kalafut]

I landed at that same commit too through other means. I ran a forked version of our tests using the old write, but the new read, and get the error you reported. We're discussing next steps now.

Related PR: #4534

[jefferai]

This will be fixed in 0.10.3.

[kalafut]

@mjacksonw Now that this is merged, if you get a chance to retest with master it would be a very useful confirmation that this fully fixed your issue.