Briefly, this error occurs when Elasticsearch tries to connect to a URL with a protocol that it doesn’t recognize. This could be due to a typo in the protocol name or using a protocol that isn’t supported. To resolve this issue, you should first check the URL for any typos or incorrect protocol names. If the protocol is correct, ensure that it is one that Elasticsearch supports. If it’s not supported, you may need to install additional libraries or plugins to add support for that protocol.
This guide will help you check for common problems that cause the log ” unknown url protocol from URL [” + url + “] ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: repositories.
Overview
An Elasticsearch snapshot provides a backup mechanism that takes the current state and data in the cluster and saves it to a repository (read snapshot for more information). The backup process requires a repository to be created first. The repository needs to be registered using the _snapshot endpoint, and multiple repositories can be created per cluster. The following repository types are supported:
Repository types
| Repository type | Configuration type |
|---|---|
| Shared file system | Type: “fs” |
| S3 | Type : “s3” |
| HDFS | Type :“hdfs” |
| Azure | Type: “azure” |
| Google Cloud Storage | Type : “gcs” |
Examples
To register an “fs” repository:
PUT _snapshot/my_repo_01
{
"type": "fs",
"settings": {
"location": "/mnt/my_repo_dir"
}
}Notes and good things to know
- S3, HDFS, Azure and Google Cloud require a relevant plugin to be installed before it can be used for a snapshot.
- The setting, path.repo: /mnt/my_repo_dir needs to be added to elasticsearch.yml on all the nodes if you are planning to use the repo type of file system. Otherwise, it will fail.
- When using remote repositories, the network bandwidth and repository storage throughput should be high enough to complete the snapshot operations normally, otherwise you will end up with partial snapshots.
Log Context
Log “unknown url protocol from URL [” + url + “]” class name is URLRepository.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
* Makes sure that the url is white listed or if it points to the local file system it matches one on of the root path in path.repo
*/
private URL checkURL(URL url) {
String protocol = url.getProtocol();
if (protocol == null) {
throw new RepositoryException(getMetadata().name(); "unknown url protocol from URL [" + url + "]");
}
for (String supportedProtocol : supportedProtocols) {
if (supportedProtocol.equals(protocol)) {
try {
if (URIPattern.match(urlWhiteList; url.toURI())) {
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