According to the WebHDFS documentation (https://hadoop.apache.org/docs/r1.0.4/webhdfs.html#CREATE) I need to set two HTTP PUT requests, one to the namenode and one to the data node given by the first request. This works fine as long as I have access to these nodes. How does a PUT work from outside a cluster, where everything between the HTTP client and the cluster is separated by a firewall except the one entrance point, which is Knox? Does it work at all? EDIT: Now it works - here is what went wrong: Just to explain, what my mistake was: I have full access to the cluster, which made me send the first request with Knox's internal IP address. Knox answered me providing an internal address of a data node. That would work for me, since I have full access, but wouldn't for others, who just see the Knox node from outside. When using Knox with it's external IP address, the first request also returns that external IP address.
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