Unable to restore snapshot from URL repository with basic authentication

[Aswin_Kumar]

Problem:

I'm trying to create snapshot on ES instance ES1, and restore to another instance ES2. It fails to restore when the remote URL requires basic authentication.

ES version: 6.5.4

Success and failure cases:

Success case: When the website exposing the ES1 repository folder is open to the internet (no authentication), the listing/restore works fine. For example when the repo URL is "http://snapshots.example-server.com"

Failure case: When I add basic authentication to the same URL, it doesn't work. For example when the repo URL is: "http://username:password@snapshots.example-server.com"

When I try to list snapshots in the URL repository with basic authentication, the error I get is:

{
  "error": {
    "root_cause": [
      {
        "type": "repository_exception",
        "reason": "[remote-repo] could not read repository data from index blob"
      }
    ],
    "type": "repository_exception",
    "reason": "[remote-repo] could not read repository data from index blob",
    "caused_by": {
      "type": "i_o_exception",
      "reason": "Server returned HTTP response code: 401 for URL: http://username:password@snapshots.example-server.com/index.latest"
    }
  },
  "status": 500
}

The Setup:

Setting up ES1:

Step 1: Modify config file:

path.repo: ["/path/to/es1_repo"]

Step 2: Creating the repo:

PUT /_snapshot/es1_repo
{
  "type": "fs",
  "settings": {
    "location": "/path/to/es1_repo"
  }
}

Step 3: Making the repository path accessible from internet:
I have setup an nginx server on the ES1 machine, to expose "/path/to/es1_repo” directory listing, let's say at: http://snapshots.example-server.com. It has basic authentication enabled. You could, for example, access the repo as http://username:password@snapshots.example-server.com and you would see the directory listing.

Step 4: Create the snapshot:

PUT /_snapshot/es1_repo/snapshot_1?wait_for_completion=true
{
  "indices": "the_index_name",
  "ignore_unavailable": true,
  "include_global_state": false
}

Setting up ES2:

Step 5: Add to elastic config:

repositories.url.allowed_urls: "http://username:password@snapshots.example-server.com"

Step 6: Register repo

PUT _snapshot/remote-repo
{
   "type": "url",
   "settings": {
       "url": "http://username:password@snapshots.example-server.com"
   }
}

Step 7: Check if the snapshot is accessible:

GET _snapshot/remote-repo/_all

At this step the error pasted at the top appears. If I disable basic authentication, it works fine.

What could be the issue here?