Support for remote path in reindex api

[huawangpp]

Elasticsearch version: 5.x

Plugins installed: []

JVM version:

OS version:

Describe the feature:
In the 5.x reindex api, support for remote is added, e.g,
POST _reindex
{
"source": {
"remote": {
"host": "http://otherhost:9200",
"username": "user",
"password": "pass"
},
...

However the host property is strictly enforced to three parts, scheme, host and port. We host elasticsearch behind a proxy and need the ability to specify a path too. I found code in https://github.com/elastic/elasticsearch/blob/v5.2.0/modules/reindex/src/main/java/org/elasticsearch/index/reindex/RestReindexAction.java, that enforces this rule.

...
private static final Pattern HOST_PATTERN = Pattern.compile("(?[^:]+)://(?[^:]+):(?\d+)");
...

Can we add the support for path?

[nik9000]

Can we add the support for path?

Is everything in elasticsearch prefixed with some path? Like curl -XGET proxy/elasticsearch gets root url and curl -XPOST proxy/elasticsearch/test/_search is how you'd do a search? If so, path prefix wouldn't be too hard to add.

[clintongormley]

a path prefix is supported by most of the REST clients too (including the Java REST client)

[huawangpp]

@nik9000, the url is like http://host:port/path for us. There is no additional elasticsearch needed in the url, e.g, curl -XPOST proxy/test/_search

[alsyia]

We are accessing ES endpoints through a reverse proxy, and this would be really useful.

[ajhewett]

Just got bitten by this. We also have ES endpoints behind reverse proxies and are not able to use them as a source for remote reindex.
Our url is like http://host:port/elasticsearch

[DaveyDevOps]

Also a problem for us since we keep elastic behind a load balancer.

[suraj-soni]

Any updates on this ? I just got bitten by this one as well

[bleskes]

@suraj-soni no concrete plans at the moment. That said, we will definitely help anyone that is willing put up a PR.