A Partially-Successful Venture Into Improving Reverse Proxies With Domino

Jan 30, 2021, 9:00 PM

I've long been an advocate for Domino's HTTPEnableConnectorHeaders notes.ini setting. That's the one that lets you pass some WebSphere-derived headers like $WSRA and (particularly-dangerously) $WSRU to Domino and have them fully override the normal values for the incoming host, user, and more.

I'm still a big fan of it, but it always come with the irritating absolute requirement that Domino not be publicly-accessible, lest any schmoe come along and pretend to be any user on your server. That's fine and all, but sometimes it's useful to have Domino be accessible without the proxy, such as for troubleshooting. What I really want it selective enabling of this feature based on source IP. So I set out this weekend to try to implement this.

The Core Idea

The mechanism for doing the lowest-level manipulation you can with HTTP on Domino is to use DSAPI, the specialized API for the web server task specifically. Unfortunately, working with DSAPI means writing a native library with C ABI entrypoints for a handful of known functions. I don't enjoy writing C (though I respect it thoroughly), but I've done it before, so I set out making a project plan.

My goal was to support the X-Forwarded-* headers that are common among reverse proxies, allowing administrators to use this common idiom instead of the $WS* headers, and also having the side effect of removing the "act as this user" part from the equation. I figured I'd make up a notes.ini property that took a comma-separated set of IP patterns, look for requests coming in from those hosts, and elevate the X-Forwarded-* headers in them up to their equivalent real properties.

Initial Side Trip Into Rust

Since C in the hands of a dilettante such as myself has a tendency to result in crashed servers and memory bugs, I figured this might be a good opportunity to learn Rust, the programming language that sprung out of Mozilla-the-organization that focuses heavily on safety, and which has some mechanisms for low-level C interoperability.

I figured this would let me learn the language, have a safer program, and avoid having to bring in third-party C libraries for e.g. regex matching.

I made some progress on this, getting to the point where I was able to actually get the filter compiled and loaded properly. However, I ended up throwing up my hands and shelving it for now when I got lost in the weeds of how to call function pointers contained in pointers to C structs. I'm sure it's possible, but I figured I shouldn't keep spending all my time working out fiddly details before I even knew if what I wanted to do was possible.

Back to C

So, hat in hand, I returned to C. Fortunately, I realized that fnmatch(3) would suit my pattern-matching needs just fine, so I didn't actually need to worry about regexes after all.

Jaw set and brimming with confidence, I set out writing the filter. I cast my mind back to my old AP Computer Science days to remember how to do a linked list to allow for an arbitrary number of patterns, got my filter registered, and then set about intercepting requests.

However... it looks like I can't actually do what I want. The core trouble is this: while I can intercept the request fairly early and add or override headers, it seems that the server/CGI variables - like REMOTE_HOST - are read-only. So, while I could certainly identify the remote host as a legal proxy server and then read the X-Forwarded-For header, I can't do anything with that information. Curses.

My next thought was that I could stick with the $WS* headers on the proxy side, but then use a DSAPI filter to remove them when they're being sent from an unauthorized host. Unfortunately, I was stymied there too: the acceptance of those headers happens before any of the DSAPI events fire. So, by the time I can see the headers, I don't have any record of the true originating host - only the one sent in via the $WSRA header.

The Next-Best Route

Since I can't undo the $WS* processing, I'd have to find a way to identify the remote proxy other than its address. I decided that, while not ideal, I could at least do this with a shared secret. So that's what I've settled on for now: you can specify a value in the HTTPConnectorHeadersSecret notes.ini property and then the filter will verify that $WS*-containing requests also include the header X-ConnectorHeaders-Secret with that value. When it finds a request with a connector header but without a matching secret, it unceremoniously drops the request into processing oblivion, resulting in a 404.

I'm not as happy with this as I would have been with my original plan, but I figure it should work. Or, at least, I figure it will enough that it's worth mulling over for a while to decide if I want to deploy it anywhere. In the mean time, it's up on GitHub for anyone curious.

Additionally, kindly go vote for the X-Forwarded-For ideas on the Domino Ideas portal, since this should really be built in.

fontconfig, Java, and Domino 11

Jan 29, 2021, 5:09 PM

Tags: java

In my last post, I quickly mentioned some trouble I had run into with fontconfig and Poi, in the context of configuring a Docker-based Domino server. However, I think it deserves its own post, so I have something to point to if others run into the same trouble down the line.

The Upshot

The upshot of the issue is that, if you're going to use Poi or or other graphics-adjacent Java libraries in Domino 11 on Linux, you'll need fontconfig and potentially some other support files installed on your system. If you have any GUI stuff installed, they'll probably be there, but it's common for them to be missing on headless servers.

For the official Domino Docker image, which uses Red Hat's package system, I wrote this Dockerfile for my derivative version:

FROM domino-docker:V1101FP2_10202020prod
USER root
RUN yum install --assumeyes fontconfig urw-fonts
USER notes

On Debian-based systems, I believe you just need apt install fontconfig.

The Details

AdoptOpenJDK builds of Java apparently don't include the same font-related support files that the Oracle ones did, and that results in calls made to the AWT layer to throw NullPointerExceptions at various times related to getting font information. This has shown up in a couple issues over in the openjdk-support project on GitHub, with two representative ones being:

https://github.com/AdoptOpenJDK/openjdk-support/issues/80

java.lang.NullPointerException
  at sun.awt.FcFontManager.getDefaultPlatformFont(FcFontManager.java:76)
  at sun.font.SunFontManager$2.run(SunFontManager.java:433)
  ...

https://github.com/AdoptOpenJDK/openjdk-build/issues/693

java.lang.NullPointerException
  at sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
  at sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:219)
  at sun.awt.FontConfiguration.init(FontConfiguration.java:107)
  ...

Domino 11 switched from IBM's proprietary variant of J9 to OpenJ9, and this is another one of the little fiddly details that isn't quite the same between the two.

Most commonly, I've found this crop up when using Poi, specifically calling autosizeColumns when generating a spreadsheet, but in theory any number of things like that will trip across this. Unfortunately, the internal JVM classes aren't terribly helpful in their error reporting, since they get several method calls in just assuming that all is well with the world before bailing with the NPEs like above.

It's a mild annoyance to deal with, but fortunately one with a straightforward fix, at least once you know what the trouble is.

Notes From A Week in Administration-Land

Jan 27, 2021, 1:06 AM

Tags: admin domino

This past week, I've been delving back into the world of Domino administration for a client and taking the opportunity to brush up on the niceties we've gotten in the past few releases. A few things struck me as I went along, so I'll list them here in no particular order.

Containers are the Way to Go

This isn't too much of a surprise, I suppose, but I imagine the only reason I'll set up a server the "installer" way again is for dev servers on Windows. Using Docker just skips over that installation phase completely and makes things so much quicker and more consistent.

It also essentially forces you to make an install-support script in the form of a Dockerfile. I started out using the default one from FlexNet, but then had a need to install fontconfig to avoid this delightful little gotcha that crops up with Poi. Since the program container is intended to be ephemeral, this meant that I had to make a Dockerfile to make a proper image for it, and now there's inherently an artifact for future admins to use.

Cluster Symmetry is a Delight

Years ago, I wrote a "Generic Replicator" agent that I would configure per-server to tell it to do the work of mirroring all NSFs. It's done yeoman's work since then, but I'm all the happier to use a built-in capability. So, tip-of-the-hat to the team that added that one in.

It'd be nice if it didn't also require notes.ini settings, but I suppose that's the way of things.

DBMT is Still Great

I know it's years and years old at this point, but I can never help but gush over DBMT. It's great and should be promoted to an on-by-default setting instead of being something you have to know to configure via a Program document.

It Still Sucks to Configure Every Server Doc

Every time I make a new server document, there's this pile of obligatory "fix the defaults" work: filling in all the stuff on the security tab, enabling web site documents, changing all the fiddly Ports tab options (including having to enable enforcing access settings (?!)), and so forth. That's on top of the giant tower of notes.ini settings in the Configuration document, but at least those can be applied to a server group and are less tedious once you know them.

I put an idea in for that last year and it sounds like it's in the works, so... that'll be nice.

The Server Doc Could Use Lots More Settings

I took the opportunity of re-laying-out servers to move as much as I can out of the data directory - namely, DAOS, transaction logs, FT indexes, and view indexes. The first two of these are configurable in the server doc, which is nice, but the latter two require specification via notes.ini properties. Since they're server-specific, it feels like a leaky abstraction to put them in a Configuration document - while it would work, and I could remove them from the doc once applied, that's just gross.

It would also be good to have a way to properly share filesystem-bound files and have them auto-deployed. For example, I have a notes.ini property in the Configuration doc for JavaUserOptionsFile=jvm.properties. The property is set automatically, but I have to create the file manually per-server. I could certainly write an agent to do that, and it'd work, but it's server configuration and belongs in the Directory.

Ideally, I'd like to be able to obliterate the container and data image, recreate them with the ID and location info, and have the server reconstitute itself after that entirely from NSF-based configuration.

HTTP is Better Than It Used to Be, But Still Needs Work

I'd love to replace my use of the WebSphere connector headers with X-Forwarded-For, but it doesn't work like that, and I'm not about to write a DSAPI filter to do it. Ideally, that'd be supported and promoted to the server config.

Same goes for Java-related settings that you just have to kind of magically know, like HTTPJVMMaxHeapSize+HTTPJVMMaxHeapSizeSet and ENABLE_SNI (I don't know why you wouldn't want SNI enabled by default).

The SSL cert manager in V12 can't come soon enough.

HTTP's better off than it was for a while, and it's nice that the TLS stack isn't dangerous now, but knowing the right way to configure it is still essentially playground lore.

Domino Configuration Tuner Deserves a New Life

I remember discovering DCT back at my old company in the 7.x days, but it unfortunately looks like it hasn't been updated since not long after that, and now doesn't even parse the current Domino version correctly. If it was brought up to date and produced reliable suggestions, it'd be huge.

As it is, my server configuration docs have all sorts of notes.ini properties like NLCACHE_SIZE=67108864 and UPDATE_NOTE_MINIMUM=40 that I saw recommended somewhere once years ago, but I have no idea whether they're still good or appropriately-sized. I want the computer to tell me that (and, in a lot of cases, just do the right thing without configuration).

Conclusion

Anyway, those are the things that came to me as I was working on this. The last few major releases have had some huge server-side improvements, and I like that the pace is continuing. Good work, server core team.

State of my Workspace 2021

Jan 15, 2021, 3:59 PM

Tags: sotu
  1. State of my Workspace 2017
  2. State of my Workspace 2021

A few years back, I wrote a post about the State of my Workspace, and I figure now is as good a time as any to write an updated version.

That said, looking through my old post, it's a little surprising how much remains the same, considering how many of the categories where allegedly in transition at the time.

Eclipse is Eternal, Apparently

Over the years, I've spent varying amounts of time in IntelliJ, and it's remarkably good in a lot of ways. I love how well-integrated its features are, and the revamped Endpoints pane in the latest releases is outstanding. It's speedy, consistently-updated, and well-considered. It particularly shines when working with a single app (either an individual thing or a small multi-module project), such as working on this blog.

That said, I still use Eclipse daily and always return to it when I try to switch away. Eclipse itself has been improving steadily too. Recent quarterly releases have focused a lot on performance, and it's paid off - the switch to non-blocking completion proposals in particular has brought some of the editing snappiness that other editors revel in. In addition, the Wild Web Developer project, though still jankier than, say, VS Code, does a good-enough job bringing fully-modern JS editing to Eclipse by way of using the same underlying LSP as other editors (the fact that it's also the backbone of NSF ODP's Eclipse support helps too). It also has some of the inline Java hints like IntelliJ does now, too, dubbed "Code Minings".

There are a few things that keep me coming back to Eclipse other than just "it's speedy like others now", too. Most of my work involves working with multiple sprawling Maven trees from distinct repositories. While IntelliJ can do that by way of importing modules, Eclipse's UI just makes it easier to manage. There's also the eternal back-and-forth about Build Automatically, and I come down thoroughly on Eclipse's side there. While IntelliJ has some options to do something like that, it's not as consistent as Eclipse. With Eclipse, I can be confident that the Problems pane will always show everything applicable. In general, I just feel more in-control of a large set of projects when working in Eclipse, and that goes a long way.

Issue Trackers Are Even Worse Off Now

Keeping track of open issues for my various tasks - both open-source projects and client work - remains a real thorn in my side, and the situation has degraded further over the years. I quite liked using the app Ship years ago, but then the company behind it shut down. The Mylyn Bitbucket connector, too, kept breaking and I gave up on it entirely a while ago. This has left me back in the situation of manually checking various browser tabs to follow everything, and that stinks.

Every once in a while, I've tinkered with writing my own little coordinated issue-tracker app to bridge all the differences, but it never really gets off the ground. It's just one of those things where it never really makes sense to sink a bunch of non-billable time into slightly improving the way I manage actually-billable time. Maybe one day it'll tip over the mental threshold and I'll actually solve the problem. We'll see.

My Computer Is Due For A Change

I ended up buying the iMac Pro I mentioned in my last post, and it's been pretty decent. However, I've hit the same trouble that Marco Arment of ATP ran into, which is that the fans on this thing go constantly. It crept up over time, with them just spinning up when I would e.g. compile a bunch of stuff at once, but now they're going basically any time I use it. It's still under AppleCare, but, between the pandemic and the fact that there's no time when it's convenient for me to be without my development environment for a week, I haven't taken it in. It's just led to be getting more and more annoyed over time.

Fortunately, the M1 Macs should be an opportunity to cut the Gordian knot: my old MacBook was due for a replacement, so I'm swapping that out for an Air. In theory, that Air will be equivalent or better than the iMac Pro for the type of work I do anyway, and I'd long ago moved my Windows VM to a PC in the basement. I plan to give it a shot as my main desktop once it arrives, and that'll also give me some room to take this thing in to be fixed. I'm looking forward to that, since it'll be nice to not glare at my computer in annoyance all day.

Oh, and, since I mentioned Storage Spaces last time: since then, I took an old tower Mac Pro and installed FreeNAS in it, and it's a delight. FreeNAS is cool and I legitimately missed working with FreeBSD. So now I have that thing handling mass storage, while my gaming PC runs Windows Server and hosts my various development VMs using Hyper-V.

Other Misc. Tools

In my last post, I mentioned Franz as a coordinated tool for the ridiculous number of chat apps I had. I ended up settling on it and, other than some consistent problems with notifications and audio, it does a good-enough job. Certainly, it's a much-better experience than running all of those stupid apps individually, that's for sure.

I also did indeed make the switch from SourceTree to Tower. While I appreciated the $0 price of SourceTree, its general crashiness and tendency to hang on complex operations got to me and I've been using Tower ever since. It does exactly what it's supposed to and does it well. Nice job, Tower.

Browser-wise, I used Firefox Developer Edition for a while, but switched back to Safari when Firefox developed a tendency to somehow hard-crash my computer. I don't know if it's a computer-specific thing (likely related to whatever the fan trouble is, I'd guess) or trouble with Firefox, but it's not exactly the sort of thing I want to have to diagnose. Safari is speedy and I'm getting used to the developer tools, so it's a fine replacement.

For mail, I (and my company) have been using Spark for a while, and it's great. The ability to share emails and have inline threads among people in your organization is wonderful.

For calendars, I use Fantastical. I miss the days when I didn't have to really care about calendars at all, but, given that I regularly have meetings, this does a splendid job dealing with them. I quite appreciate the recent additions of weather reports and the automatic detection of meeting URLs, too.

For blogging, I use MarsEdit, both because it's good on its own and because writing an API for my blog meant I didn't need to bother making a good editing UI on my own. I think it's also just conceptually good to use tools that work with open protocols like that.

Getting Started with Hotwire in a Java Webapp

Jan 12, 2021, 10:19 PM

Whenever I have a great deal of discretion over how a web app is made these days, I like to push to see how simple I can make the front end portion. I spend some of my client time writing heavy client-JS front ends in React and Angular and what-have-you, and, though I get why they are good, I kind of hate them all.

One of the manifestations of my desires has been this very blog, where I set out to try not only some interesting current tools on the Java side, but also challenged myself heavily to use little to no JavaScript. On that front, I was tremendously successful - and, in fact, the only JavaScript on here is the Turbolinks library, which intercepts same-app links and updates the changed parts inline, without the server knowing about the "partial refresh" going on.

Since then, Turbolinks merged with its cousin Stimulus and apotheosized into Hotwire, which is somewhere in between a JavaScript framework and a manifesto. Specifically, it's a manifesto to my liking, so I've been champing at the bit to use it more.

Hotwire Overview

The "Hotwire" name is a cheeky truncation of HTML-over-the-wire, which itself is a neologism for how the web has historically worked: your server sends HTML, and then your browser does stuff with that. It "needs" a new name to set it apart from full-JS apps, which amount to basically sending an application to the browser, having it initialize the app, and then having the app do what would otherwise be the server's job by way of shuttling JSON around.

Turbo is that part that subsumed Turbolinks, and it focuses on enhancing existing HTML and providing a few web components to bring single-page-application niceties to server-rendered apps. The "Drive" part is Turbolinks, so that was familiar to me. What interested me next was Turbo Frames.

Turbo Frames

If you've ever used the XPages Dojo Tab Container's partialRefresh property before, Turbo Frames will be familiar. There are two main ways you can go about using it: making a "frame" that contains some navigable content (say, a form) that will then refresh in-place or making a lazy-loaded frame that pulls from another URL. The latter is what interested me now, and is what carries similar benefits to the Tab Container. It lets you serve the main page and then defer complex complication of an inner part without having to write your own JavaScript to do an API call or otherwise populate the section.

In my case, I wanted to do something very similar to the example. I have my main page, then a sidebar that can be potentially complicated to generate. So, I set up a Turbo Frame using this bit of JSP:

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<turbo-frame id="links" src="${pageContext.request.contextPath}/links"></turbo-frame>

The only difference from the example, really, is the bit of EL in ${...}, which just makes sure that the final URL adapts to wherever the app is hosted.

The "links" resource there is another MVC controller that renders a different JSP page, truncated like:

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<html>
    <head>
        <script type="text/javascript" src="${pageContext.request.contextPath}/webjars/hotwired__turbo/7.0.0-beta.2/dist/turbo.es5-umd.js"></script>
    </head>
    <body>
        <turbo-frame id="links">
            <!-- expensive content here -->
        </turbo-frame>
    </body>
</html>

The <turbo-frame id="links"> on the initiating page matches up with the one in the embedded page to figure out what to extract and render.

One little side note here is my use of WebJars to bring in Turbo. This isn't an NPM-based project, so there's no package.json bringing the dependency in, but I also didn't want to just paste the JS into my project. Fortunately, WebJars does yeoman's work: it makes various JS libraries available in Servlet-friendly Java JAR format, giving you a JAR with the JS from whatever the library is in META-INF/resources. In turn, an at-least-reasonably-modern servlet container will serve files up from there as if they're part of your main app. That way, you can just use a Maven dependency and not have to worry.

A Hitch: 406 Not Acceptable

Edit 2021-01-13: Thanks to a new release of Turbo, this workaround is no longer needed.

When I first put this together, I saw that Turbo was doing its job of fetching from the remote URL, but it was getting a 406 Not Acceptable response from the server. It took me a minute to figure out why - the URL was correct, it was just a normal GET request, and nothing immediately stood out as a problem in the headers.

It turned out that the trouble was in the Accept header. To work with other Turbo components, Frames makes a request with a header like Accept: text/html; turbo-stream, text/html, application/xhtml+xml. That first one - text/html; turbo-stream - is problematic. I'm not sure if it's the presence of a qualifier at all on text/html, the space, or the lack of an = (as in text/html;charset=UTF-8), but Liberty didn't like it.

Since I'm not (yet, at least) using Turbo Streams, I decided to filter this out on the server. Since MVC is built on JAX-RS, I wrote a JAX-RS request filter to find any Accept values of this type and strip them out:

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@Provider
@PreMatching
public class TurboStreamAcceptFilter implements ContainerRequestFilter {
    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        MultivaluedMap<String, String> headers = requestContext.getHeaders();
        if(headers.containsKey(HttpHeaders.ACCEPT)) {
            List<String> cleaned = headers.get(HttpHeaders.ACCEPT).stream()
                .map(accept -> {
                    String[] vals = accept.split(",\\s*"); //$NON-NLS-1$
                    List<String> localClean = Arrays.stream(vals)
                        .filter(val -> val.indexOf(';') < 0)
                        .collect(Collectors.toList());
                    return String.join(", ", localClean); //$NON-NLS-1$
                })
                .collect(Collectors.toList());
            headers.put(HttpHeaders.ACCEPT, cleaned);
        }
    }
}

Since those filters happen before almost anything else, this cleared up the trouble.

Summary

Setting the Accept quirk aside, this was a pleasant success, and I look forward to using this more. I've found the modern Java stack of JAX-RS + CDI + MVC + simple JSP to be a delight, and Hotwire slots perfectly-smoothly into it. I still quire enjoy rendering HTML on the server and the associated perk of not having to duplicate business logic on both sides. Next time I have an app that requires a bit of actual JavaScript, I'll likely throw Stimulus into the mix here.