While trying to make the REST endpoints on my 1.20 Flink environment work with SSL, I discovered that the 0.0.0.0 bind-address solution won't work in this release.
It is because in YarnEntrypointUtils, the bind address is overwritten with the hostname, before it was used for creating the endpoint :) https://github.com/apache/flink/blob/release-1.20/flink-yarn/src/main/java/org/apache/flink/yarn/entrypoint/YarnEntrypointUtils.java#L68 This commit should be cherry-picked to release-1.20. if we want to make it work: https://github.com/apache/flink/commit/b138d47adbed9fc1e5a73cebf649530bc5b89e6e Do you think it's worth a Jira and the effort? Will there be more 1.20 bugfix releases in the future? Thanks, Gyula On Thu, Nov 27, 2025 at 9:51 AM Gyula Komlossi <[email protected]> wrote: > > Hi Gabor, > > Thanks for the quick response. I was wondering how a third config > parameter cloud be avoided. There are two already (rest.address and > rest.bind-address) and a third one would make confusion, but I > understand, the existing behavior shouldn't be changed. > Also the rest.address is supposed to be "The address that should be > used by clients to connect to the server". Just like with the Kafka > advertised listeners. > > For my testing I just added an extra condition to this: > if (bindAddress.getAddress().isAnyLocalAddress() || isHttpsEnabled()) { > advertisedAddress = this.restAddress; > } else { > advertisedAddress = bindAddress.getAddress().getHostAddress(); > } > but it's far from ideal, it's just a workaround for now :) > > So I don't have a real alternative for this.. > > Best, > Gyula > > On Thu, Nov 27, 2025 at 9:04 AM Gabor Somogyi <[email protected]> > wrote: > > > > BTW if you have any alternative way just share it either in the jira or in > > PR 🙂 > > > > On Thu, Nov 27, 2025 at 9:02 AM Gabor Somogyi <[email protected]> > > wrote: > >> > >> Hi Gyula, > >> > >> We've discussed the issue but no PR available yet. > >> Feel free and cc me if you have time... > >> > >> BR, > >> G > >> > >> > >> On Thu, Nov 27, 2025 at 8:52 AM Gyula Komlossi <[email protected]> > >> wrote: > >>> > >>> Hi Yaroslav, Gabor, > >>> > >>> I just ran into this issue, when tried to configure SSL for the REST > >>> endpoint. I'm wondering what the preferred approach is with HTTPS on this > >>> REST endpoint or if there is any code change in progress. > >>> Have you been able to solve this one way or another, or started preparing > >>> a code change for it? > >>> > >>> I was able to make this work with a small code change in the > >>> RestServerEndpoint class to use the rest.address as the advertisedAddress > >>> with HTTPS, but I’m looking forward to the official improvement. > >>> Thank you both for taking care of this! > >>> > >>> Best, > >>> Gyula > >>> > >>> > >>> On 2025/08/19 20:34:06 Yaroslav Chernysh wrote: > >>> > https://issues.apache.org/jira/browse/FLINK-38269 > >>> > > >>> > On 2025/08/19 18:58:59 Gabor Somogyi wrote: > >>> > > You can file a jira and open a PR too so feel free. > >>> > > > >>> > > G > >>> > > > >>> > > On Tue, Aug 19, 2025, 19:51 Yaroslav Chernysh <[email protected]> > >>> > wrote: > >>> > > > >>> > > > Hi Gabor, > >>> > > > > >>> > > > > >>> > > > Just to avoid any misunderstanding, I've been waiting for the > >>> > ticket > >>> > > > from you. I assumed that you were going to do it. Please let me > >>> > know if > >>> > > > I got you wrong and I should create it myself. > >>> > > > > >>> > > > > >>> > > > Best regards, > >>> > > > > >>> > > > Yaroslav > >>> > > > > >>> > > > > >>> > > > On 2025/08/18 14:07:51 Gabor Somogyi wrote: > >>> > > > > Yeah, please read the how to contribute guide if you haven't done > >>> > > > already. > >>> > > > > > >>> > > > > G > >>> > > > > > >>> > > > > On Mon, Aug 18, 2025 at 4:00 PM Yaroslav Chernysh > >>> > <[email protected]> > >>> > > > > wrote: > >>> > > > > > >>> > > > > > Hi Gabor, > >>> > > > > > > >>> > > > > > > >>> > > > > > Thanks, let's add a new option then to make advertised address > >>> > > > > > configurable and document the default behavior. Would you mind > >>> > filing > >>> > > > a > >>> > > > > > ticket for that? > >>> > > > > > > >>> > > > > > > >>> > > > > > Regards, > >>> > > > > > > >>> > > > > > Yaroslav > >>> > > > > > > >>> > > > > > > >>> > > > > > On 2025/08/18 13:41:54 Gabor Somogyi wrote: > >>> > > > > > > Hi Yaroslav, > >>> > > > > > > > >>> > > > > > > Having a config option to advertise something else is what I > >>> > can > >>> > > > > > support. > >>> > > > > > > Needless to say the actual behavior would remain as default. > >>> > > > > > > > >>> > > > > > > G > >>> > > > > > > > >>> > > > > > > > >>> > > > > > > On Mon, Aug 18, 2025 at 3:28 PM Yaroslav Chernysh > >>> > <[email protected]> > >>> > > > > > > wrote: > >>> > > > > > > > >>> > > > > > > > Hi Gabor, > >>> > > > > > > > > >>> > > > > > > > I got your point on using `getHostName()`. Thank you for > >>> > such a > >>> > > > > > detailed > >>> > > > > > > > explanation. > >>> > > > > > > > > >>> > > > > > > > What do you think about advertising rest.address instead? > >>> > In > >>> > > > case of > >>> > > > > > > > YARN (at least on my environment), this is already set by > >>> > YARN > >>> > > > to a NM > >>> > > > > > > > hostname, so rDNS would be avoided. > >>> > > > > > > > > >>> > > > > > > > Thanks, > >>> > > > > > > > > >>> > > > > > > > Yaroslav > >>> > > > > > > > > >>> > > > > > > > > >>> > > > > > > > On 2025/08/15 21:12:58 Gabor Somogyi wrote: > >>> > > > > > > > > Hi Yaroslav, > >>> > > > > > > > > > >>> > > > > > > > > Thanks for your efforts in finding out all the details. > >>> > > > > > > > > > >>> > > > > > > > > I think making `getHostName` possible with a config + > >>> > some > >>> > > > > > additional > >>> > > > > > > > > warnings in the documentation can be considered. > >>> > > > > > > > > You need to evaluate your security standards but you win > >>> > > > something > >>> > > > > > on > >>> > > > > > > > one > >>> > > > > > > > > side and introduce new attack vector on the other side. > >>> > > > > > > > > > >>> > > > > > > > > I would write something similar in the documentation, and > >>> > I also > >>> > > > > > suggest > >>> > > > > > > > > you consider these for your own situation as well: > >>> > > > > > > > > - rDNS is not trustworthy for security decisions. > >>> > Attackers with > >>> > > > > > control > >>> > > > > > > > > over PTR (or via poisoning/misconfig) can return > >>> > arbitrary > >>> > > > names. > >>> > > > > > > > > MITRE tracks this as CWE-350 [1] (Reliance on Reverse > >>> > DNS for > >>> > > > > > > > Security). If > >>> > > > > > > > > you base TLS host checks on rDNS, it’s bypassable. > >>> > > > > > > > > - Slow or failing DNS causes blocking delays (seconds) > >>> > in JVM > >>> > > > > > lookups. > >>> > > > > > > > > OpenJDK issues document repeated timeouts and lack of > >>> > > > > > > > > effective caching paths for some rDNS calls. Putting > >>> > rDNS in > >>> > > > > > critical > >>> > > > > > > > paths > >>> > > > > > > > > (TLS, handshake, request handling) can amplify random > >>> > outages. > >>> > > > > > > > > > >>> > > > > > > > > All in all I'm not yet convinced that this issue appears > >>> > in > >>> > > > other > >>> > > > > > > > trending > >>> > > > > > > > > environments like k8s. > >>> > > > > > > > > Adding this together with the mentioned risks I > >>> > personally > >>> > > > wouldn't > >>> > > > > > > > merge > >>> > > > > > > > > it to the main repo. > >>> > > > > > > > > > >>> > > > > > > > > BR, > >>> > > > > > > > > G > >>> > > > > > > > > > >>> > > > > > > > > [1] https://cwe.mitre.org/data/definitions/350.html > >>> > > > > > > > > > >>> > > > > > > > > > >>> > > > > > > > > On Fri, Aug 15, 2025 at 7:44 PM Yaroslav Chernysh > >>> > > > <[email protected]> > >>> > > > > > > > > wrote: > >>> > > > > > > > > > >>> > > > > > > > > > Hi Gobor, > >>> > > > > > > > > > > >>> > > > > > > > > > Thank you for such a quick response, I appreciate it. > >>> > > > > > > > > > > >>> > > > > > > > > > Actually, I'm not very good at all this security and > >>> > > > networking > >>> > > > > > > > stuff, so > >>> > > > > > > > > > I apologize in advance if I'm wrong in some statement. > >>> > > > > > > > > > > >>> > > > > > > > > > > Does YARN containers share the host’s network in your > >>> > case? > >>> > > > > > > > > > > >>> > > > > > > > > > Yes, it does. And as far as I have researched, it > >>> > always does, > >>> > > > > > > > possibly > >>> > > > > > > > > > only unless you have configured YARN to use Docker > >>> > containers > >>> > > > > > > > > > > >>> > > > > > > > < > >>> > > > > > > > > >>> > > > > > > >>> > > > > > > >>> > > > > >>> > > > > >>> > https://hadoop.apache.org/docs/r3.4.1/hadoop-yarn/hadoop-yarn-site/DockerContainers.html > >>> > > > > > > > >, > >>> > > > > > > > > > which is definitely not my case. I have also done some > >>> > > > testing on > >>> > > > > > > > my node, > >>> > > > > > > > > > which has 2 IP addresses: > >>> > > > > > > > > > > >>> > > > > > > > > > - With default rest.bind-address (set by YARN to Node > >>> > > > Manager's > >>> > > > > > > > hostname), > >>> > > > > > > > > > the only IP address that opens a port is the one that > >>> > NM > >>> > > > > > hostname is > >>> > > > > > > > > > resolved to. The other one (not sure where it comes > >>> > from, > >>> > > > this is > >>> > > > > > a > >>> > > > > > > > VM) > >>> > > > > > > > > > remains closed > >>> > > > > > > > > > > >>> > > > > > > > > > - With rest.bind-address set to 0.0.0.0, the port is > >>> > open and > >>> > > > > > > > accessible > >>> > > > > > > > > > via both IP addresses > >>> > > > > > > > > > > >>> > > > > > > > > > > However if you have a single IP then using 0.0.0.0 > >>> > and > >>> > > > > > binding it to > >>> > > > > > > > > > lo + eth0 is something what I wouldn't worry about. > >>> > > > > > > > > > > >>> > > > > > > > > > I got the point and basically I agree here, but I'm not > >>> > > > sure how > >>> > > > > > > > > > future-proof this approach is. How probable is a > >>> > scenario in > >>> > > > > > which the > >>> > > > > > > > > > environment (single IP node) is changed (to a > >>> > multi-homed > >>> > > > > > node), but > >>> > > > > > > > > > unchanged configuration (still listening on 0.0.0.0) > >>> > now leads > >>> > > > > > to an > >>> > > > > > > > > > excessive network exposure? Either way, that's not my > >>> > case. > >>> > > > And I > >>> > > > > > > > think > >>> > > > > > > > > > this is not restricted to YARN too: binding to all > >>> > > > interfaces in > >>> > > > > > > > Standalone > >>> > > > > > > > > > deployment might be too excessive as well. > >>> > > > > > > > > > > >>> > > > > > > > > > > but you still have control on firewall, right? > >>> > > > > > > > > > > >>> > > > > > > > > > Probably yes (saying for an average user). This would > >>> > probably > >>> > > > > > > > cover the > >>> > > > > > > > > > excessive binding leak, however only at the firewall > >>> > level > >>> > > > and not > >>> > > > > > > > at the > >>> > > > > > > > > > "core". This adds a dependency on firewall. I'm not > >>> > saying > >>> > > > it's > >>> > > > > > > > bad, but > >>> > > > > > > > > > rather that using the defense-in-depth approach and > >>> > doing both > >>> > > > > > limited > >>> > > > > > > > > > binding and adding firewall would be even better than > >>> > > > relying on > >>> > > > > > > > firewall > >>> > > > > > > > > > only. > >>> > > > > > > > > > > >>> > > > > > > > > > I hope all the above proves the point that even with > >>> > good > >>> > > > enough > >>> > > > > > > > > > environment (number of IP address + firewall) it still > >>> > does > >>> > > > make > >>> > > > > > > > sense to > >>> > > > > > > > > > restrict the binding. At least that's how I see this, > >>> > please > >>> > > > > > > > correct me if > >>> > > > > > > > > > I'm wrong. > >>> > > > > > > > > > > >>> > > > > > > > > > > introduce reverse DNS lookup as a must have feature > >>> > > > > > > > > > > >>> > > > > > > > > > Could we make it optional and disabled by default? > >>> > > > > > > > > > > >>> > > > > > > > > > Thanks, > >>> > > > > > > > > > > >>> > > > > > > > > > Yaroslav > >>> > > > > > > > > > > >>> > > > > > > > > > On 2025/08/14 21:32:40 Gabor Somogyi wrote: > >>> > > > > > > > > > > Hi Yaroslav, > >>> > > > > > > > > > > > >>> > > > > > > > > > > First of all I would like to understand why you think > >>> > > > binding to > >>> > > > > > > > 0.0.0.0 > >>> > > > > > > > > > is > >>> > > > > > > > > > > less secure in your case. Correct me if I'm wrong: > >>> > > > > > > > > > > Does YARN containers share the host’s network in your > >>> > > > case? On a > >>> > > > > > > > > > > multi-homed node, 0.0.0.0 exposes on every host > >>> > interface, > >>> > > > > > > > > > > which can be less secure than binding to a specific > >>> > host > >>> > > > IP. So > >>> > > > > > > > this case > >>> > > > > > > > > > > pinning can matter. > >>> > > > > > > > > > > > >>> > > > > > > > > > > However if you have a single IP then using 0.0.0.0 > >>> > and > >>> > > > binding > >>> > > > > > it > >>> > > > > > > > to lo + > >>> > > > > > > > > > > eth0 is something what I wouldn't worry about. > >>> > > > > > > > > > > Like a "normal" kubernetes pod (default networking, > >>> > single > >>> > > > > > > > interface, no > >>> > > > > > > > > > > hostNetwork) has no such issue. > >>> > > > > > > > > > > > >>> > > > > > > > > > > As a general remark. Let's say you expose the REST > >>> > endpoint > >>> > > > > > on 2 IP > >>> > > > > > > > > > > addresses but you still have control on firewall, > >>> > right? > >>> > > > > > > > > > > > >>> > > > > > > > > > > The main reason why I'm asking these questions is > >>> > because > >>> > > > using > >>> > > > > > > > > > > `getHostName` would introduce reverse DNS lookup as a > >>> > > > must have > >>> > > > > > > > feature. > >>> > > > > > > > > > > That could cause quite some turbulences at heavy > >>> > users by > >>> > > > > > additional > >>> > > > > > > > > > > traffic, PTR records can be wrong or spoofed, etc... > >>> > > > > > > > > > > > >>> > > > > > > > > > > BR, > >>> > > > > > > > > > > G > >>> > > > > > > > > > > > >>> > > > > > > > > > > > >>> > > > > > > > > > > On Thu, Aug 14, 2025 at 8:13 PM Yaroslav Chernysh > >>> > > > > > <[email protected]> > >>> > > > > > > > > > <[email protected]> > >>> > > > > > > > > > > wrote: > >>> > > > > > > > > > > > >>> > > > > > > > > > > > Hi Flink community, > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > Is there a particular reason to advertise Job > >>> > Manager's > >>> > > > REST > >>> > > > > > > > endpoint > >>> > > > > > > > > > > > address in a form of IP address instead of > >>> > hostname? More > >>> > > > > > > > precisely, > >>> > > > > > > > > > I'm > >>> > > > > > > > > > > > talking about this code block > >>> > > > > > > > > > > > > >>> > > > > > > > > > > >>> > > > > > > > < > >>> > > > > > > > > >>> > > > > > > >>> > > > > > > >>> > > > > >>> > > > > >>> > https://github.com/apache/flink/blob/release-2.0.0/flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestServerEndpoint.java#L298-L304 > >>> > > > > > > > > > >>> > > > > > > > > > > >>> > > > > > > > < > >>> > > > > > > > > >>> > > > > > > >>> > > > > > > >>> > > > > >>> > > > > >>> > https://github.com/apache/flink/blob/release-2.0.0/flink-runtime/src/main/java/org/apache/flink/runtime/rest/RestServerEndpoint.java#L298-L304 > >>> > > > > > > > > > >>> > > > > > > > > > in > >>> > > > > > > > > > > > RestServerEndpoint.java: > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > final InetSocketAddress bindAddress = > >>> > (InetSocketAddress) > >>> > > > > > > > > > > > serverChannel.localAddress(); > >>> > > > > > > > > > > > final String advertisedAddress; > >>> > > > > > > > > > > > if (bindAddress.getAddress().isAnyLocalAddress()) { > >>> > > > > > > > > > > > advertisedAddress = this.restAddress; > >>> > > > > > > > > > > > } else { > >>> > > > > > > > > > > > advertisedAddress = > >>> > > > > > > > > > > > bindAddress.getAddress().getHostAddress(); > >>> > > > > > > > > > > > } > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > That is (as far as I understood), if > >>> > rest.bind-address > >>> > > > is set > >>> > > > > > > > to the > >>> > > > > > > > > > > > 0.0.0.0 wildcard (which means binding to all > >>> > available > >>> > > > > > > > interfaces), > >>> > > > > > > > > > then > >>> > > > > > > > > > > > the advertised address will be the value of > >>> > rest.address. > >>> > > > > > > > Otherwise, an > >>> > > > > > > > > > > > address in a form of IP address of the specified > >>> > > > > > rest.bind-address > >>> > > > > > > > > > will be > >>> > > > > > > > > > > > used. > >>> > > > > > > > > > > > What if I want to bind the REST endpoint to some > >>> > specific > >>> > > > > > > > address (for > >>> > > > > > > > > > > > security reasons), but at the same time advertise > >>> > it in > >>> > > > the > >>> > > > > > form > >>> > > > > > > > of > >>> > > > > > > > > > > > hostname? Assuming that all the name resolution > >>> > things > >>> > > > work > >>> > > > > > > > correctly. > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > For me particularly, the problem this creates is > >>> > with > >>> > > > SSL. The > >>> > > > > > > > > > certificate > >>> > > > > > > > > > > > I have for the Job Manager (REST connectivity) is > >>> > created > >>> > > > > > with a > >>> > > > > > > > > > hostname > >>> > > > > > > > > > > > and not an IP address. I run Flink on YARN and > >>> > this way > >>> > > > the > >>> > > > > > > > default > >>> > > > > > > > > > value > >>> > > > > > > > > > > > for rest.bind-address is Node Manager's hostname > >>> > (thus, > >>> > > > not > >>> > > > > > the > >>> > > > > > > > 0.0.0.0 > >>> > > > > > > > > > > > wildcard), and the same goes for rest.address. This > >>> > > > way, the > >>> > > > > > > > advertised > >>> > > > > > > > > > > > address is in the form of an IP address. I'd like > >>> > to > >>> > > > access > >>> > > > > > > > Flink's UI > >>> > > > > > > > > > via > >>> > > > > > > > > > > > the YARN Resource Manager proxy ("Tracking URL" in > >>> > the > >>> > > > > > application > >>> > > > > > > > > > page) > >>> > > > > > > > > > > > that has the Job Manager's certificate in its > >>> > truststore. > >>> > > > > > > > However, due > >>> > > > > > > > > > to > >>> > > > > > > > > > > > the Flink being advertised to Resource Manager with > >>> > the IP > >>> > > > > > > > address and > >>> > > > > > > > > > the > >>> > > > > > > > > > > > certificate holds the hostname, the connection from > >>> > > > Resource > >>> > > > > > > > Manager > >>> > > > > > > > > > to Job > >>> > > > > > > > > > > > Manager fails with: > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > javax.net.ssl.SSLPeerUnverifiedException: > >>> > Certificate for > >>> > > > > > > > > > <192.168.33.11> > >>> > > > > > > > > > > > doesn't match any of the subject alternative > >>> > names: [] > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > The only way I can fix this (without code changes) > >>> > is by > >>> > > > > > > > explicitly > >>> > > > > > > > > > > > setting rest.bind-address to 0.0.0.0, which is not > >>> > > > secure, as > >>> > > > > > > > far as I > >>> > > > > > > > > > > > understand (less secure than binding to a specific > >>> > > > address). > >>> > > > > > > > > > > > However, if I substitute the getHostAddress() call > >>> > in > >>> > > > the code > >>> > > > > > > > block > >>> > > > > > > > > > above > >>> > > > > > > > > > > > with the getHostName(), the issue is gone. > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > So, my question is: is there any particular reason > >>> > not to > >>> > > > > > > > > > > > use getHostName() here (assuming hostname is > >>> > available)? > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > Thanks, > >>> > > > > > > > > > > > Yaroslav > >>> > > > > > > > > > > > > >>> > > > > > > > > > > > >>> > > > > > > > > > > >>> > > > > > > > > > >>> > > > > > > > > >>> > > > > > > > >>> > > > > > > >>> > > > > > >>> > > > > >>> > > > >>> >
