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---------------------- HAProxy how-to ---------------------- version 1.5-dev7 willy tarreau 2011/09/10 1) How to build it ------------------ To build haproxy, you will need : - GNU make. Neither Solaris nor OpenBSD's make work with the GNU Makefile. However, specific Makefiles for BSD and OSX are provided. - GCC between 2.91 and 4.5.0. Others may work, but not tested. - GNU ld Also, you might want to build with libpcre support, which will provide a very efficient regex implementation and will also fix some badness on Solaris' one. To build haproxy, you have to choose your target OS amongst the following ones and assign it to the TARGET variable : - linux22 for Linux 2.2 - linux24 for Linux 2.4 and above (default) - linux24e for Linux 2.4 with support for a working epoll (> 0.21) - linux26 for Linux 2.6 and above - solaris for Solaris 8 or 10 (others untested) - freebsd for FreeBSD 5 to 8.0 (others untested) - openbsd for OpenBSD 3.1 to 4.6 (others untested) - cygwin for Cygwin - generic for any other OS. - custom to manually adjust every setting You may also choose your CPU to benefit from some optimizations. This is particularly important on UltraSparc machines. For this, you can assign one of the following choices to the CPU variable : - i686 for intel PentiumPro, Pentium 2 and above, AMD Athlon - i586 for intel Pentium, AMD K6, VIA C3. - ultrasparc : Sun UltraSparc I/II/III/IV processor - native : use the build machine's specific processor optimizations - generic : any other processor or no specific optimization. (default) Alternatively, you may just set the CPU_CFLAGS value to the optimal GCC options for your platform. You may want to build specific target binaries which do not match your native compiler's target. This is particularly true on 64-bit systems when you want to build a 32-bit binary. Use the ARCH variable for this purpose. Right now it only knows about a few x86 variants (i386,i486,i586,i686,x86_64), two generic ones (32,64) and sets -m32/-m64 as well as -march=<arch> accordingly. If your system supports PCRE (Perl Compatible Regular Expressions), then you really should build with libpcre which is between 2 and 10 times faster than other libc implementations. Regex are used for header processing (deletion, rewriting, allow, deny). The only inconvenient of libpcre is that it is not yet widely spread, so if you build for other systems, you might get into trouble if they don't have the dynamic library. In this situation, you should statically link libpcre into haproxy so that it will not be necessary to install it on target systems. Available build options for PCRE are : - USE_PCRE=1 to use libpcre, in whatever form is available on your system (shared or static) - USE_STATIC_PCRE=1 to use a static version of libpcre even if the dynamic one is available. This will enhance portability. - with no option, use your OS libc's standard regex implemntation (default). Warning! group references on Solaris seem broken. Use static-pcre whenever possible. Recent systems can resolve IPv6 host names using getaddrinfo(). This primitive is not present in all libcs and does not work in all of them either. Support in glibc was broken before 2.3. Some embedded libs may not properly work either, thus, support is disabled by default, meaning that some host names which only resolve as IPv6 addresses will not resolve and configs might emit an error during parsing. If you know that your OS libc has reliable support for getaddrinfo(), you can add USE_GETADDRINFO=1 on the make command line to enable it. This is the recommended option for most Linux distro packagers since it's working fine on all recent mainstream distros. It is automatically enabled on Solaris 8 and above, as it's known to work. By default, the DEBUG variable is set to '-g' to enable debug symbols. It is not wise to disable it on uncommon systems, because it's often the only way to get a complete core when you need one. Otherwise, you can set DEBUG to '-s' to strip the binary. For example, I use this to build for Solaris 8 : $ make TARGET=solaris CPU=ultrasparc USE_STATIC_PCRE=1 And I build it this way on OpenBSD or FreeBSD : $ make -f Makefile.bsd REGEX=pcre DEBUG= COPTS.generic="-Os -fomit-frame-pointer -mgnu" In order to build a 32-bit binary on an x86_64 Linux system : $ make TARGET=linux26 ARCH=i386 If you need to pass other defines, includes, libraries, etc... then please check the Makefile to see which ones will be available in your case, and use the USE_* variables in the GNU Makefile, or ADDINC, ADDLIB, and DEFINE variables in the BSD makefiles. AIX 5.3 is known to work with the generic target. However, for the binary to also run on 5.2 or earlier, you need to build with DEFINE="-D_MSGQSUPPORT", otherwise __fd_select() will be used while not being present in the libc. 2) How to install it -------------------- To install haproxy, you can either copy the single resulting binary to the place you want, or run : $ sudo make install If you're packaging it for another system, you can specify its root directory in the usual DESTDIR variable. 3) How to set it up ------------------- There is some documentation in the doc/ directory : - architecture.txt : this is the architecture manual. It is quite old and does not tell about the nice new features, but it's still a good starting point when you know what you want but don't know how to do it. - configuration.txt : this is the configuration manual. It recalls a few essential HTTP basic concepts, and details all the configuration file syntax (keywords, units). It also describes the log and stats format. It is normally always up to date. If you see that something is missing from it, please report it as this is a bug. - haproxy-en.txt / haproxy-fr.txt : these are the old outdated docs. You should never need them. If you do, then please report what you didn't find in the other ones. - gpl.txt / lgpl.txt : the copy of the licenses covering the software. See the 'LICENSE' file at the top for more information. - the rest is mainly for developers. There are also a number of nice configuration examples in the "examples" directory as well as on several sites and articles on the net which are linked to from the haproxy web site. 4) How to report a bug ---------------------- It is possible that from time to time you'll find a bug. A bug is a case where what you see is not what is documented. Otherwise it can be a misdesign. If you find that something is stupidly design, please discuss it on the list (see the "how to contribute" section below). If you feel like you're proceeding right and haproxy doesn't obey, then first ask yourself if it is possible that nobody before you has even encountered this issue. If it's unlikely, the you probably have an issue in your setup. Just in case of doubt, please consult the mailing list archives : http://www.formilux.org/archives/haproxy/ http://marc.info/?l=haproxy Otherwise, please try to gather the maximum amount of information to help reproduce the issue and send that to the mailing list : email@example.com Please include your configuration and logs. You can mask your IP addresses and passwords, we don't need them. But it's essential that you post your config if you want people to guess what is happening. Also, keep in mind that haproxy is designed to NEVER CRASH. If you see it die without any reason, then it definitely is a critical bug that must be reported and urgently fixed. It has happened a couple of times in the past, essentially on development versions running on new architectures. If you think your setup is fairly common, then it is possible that the issue is totally unrelated. Anyway, if that happens, feel free to contact me directly, as I will give you instructions on how to collect a usable core file, and will probably ask for other captures that you'll not want to share with the list. 5) How to contribute -------------------- It is possible that you'll want to add a specific feature to satisfy your needs or one of your customers'. Contributions are welcome, however I'm often very picky about changes. I will generally reject patches that change massive parts of the code, or that touch the core parts without any good reason if those changes have not been discussed first. The proper place to discuss your changes is the HAProxy Mailing List. There are enough skilled readers to catch hazardous mistakes and to suggest improvements. I trust a number of them enough to merge a patch if they say it's OK, so using the list is the fastest way to get your code reviewed and merged. You can subscribe to it by sending an empty e-mail at the following address : firstname.lastname@example.org If you have an idea about something to implement, *please* discuss it on the list first. It has already happened several times that two persons did the same thing simultaneously. This is a waste of time for both of them. It's also very common to see some changes rejected because they're done in a way that will conflict with future evolutions, or that does not leave a good feeling. It's always unpleasant for the person who did the work, and it is unpleasant for me too because I value people's time and efforts. That would not happen if these were discussed first. There is no problem posting work in progress to the list, it happens quite often in fact. Also, don't waste your time with the doc when submitting patches for review, only add the doc with the patch you consider ready to merge. If your work is very confidential and you can't publicly discuss it, you can also mail me directly about it, but your mail may be waiting several days in the queue before you get a response. If you'd like a feature to be added but you think you don't have the skills to implement it yourself, you should follow these steps : 1. discuss the feature on the mailing list. It is possible that someone else has already implemented it, or that someone will tell you how to proceed without it, or even why not to do it. It is also possible that in fact it's quite easy to implement and people will guide you through the process. That way you'll finally have YOUR patch merged, providing the feature YOU need. 2. if you really can't code it yourself after discussing it, then you may consider contacting someone to do the job for you. Some people on the list might be OK with trying to do it. Otherwise, you can check the list of contributors at the URL below, some of the regular contributors may be able to do the work, probably not for free but their time is as much valuable as yours after all, you can't eat the cake and have it too. The list of past and regular contributors is available below. It lists not only significant code contributions (features, fixes), but also time or money donations : http://haproxy.1wt.eu/contrib.html Note to contributors: it's very handy when patches comes with a properly formated subject. There are 3 criteria of particular importance in any patch : - its nature (is it a fix for a bug, a new feature, an optimization, ...) - its importance, which generally reflects the risk of merging/not merging it - what area it applies to (eg: http, stats, startup, config, doc, ...) It's important to make these 3 criteria easy to spot in the patch's subject, because it's the first (and sometimes the only) thing which is read when reviewing patches to find which ones need to be backported to older versions. Specifically, bugs must be clearly easy to spot so that they're never missed. Any patch fixing a bug must have the "BUG" tag in its subject. Most common patch types include : - BUG fix for a bug. The severity of the bug should also be indicated when known. Similarly, if a backport is needed to older versions, it should be indicated on the last line of the commit message. If the bug has been identified as a regression brought by a specific patch or version, this indication will be appreciated too. New maintenance releases are generally emitted when a few of these patches are merged. - CLEANUP code cleanup, silence of warnings, etc... theorically no impact. These patches will rarely be seen in stable branches, though they may appear when they remove some annoyance or when they make backporting easier. By nature, a cleanup is always minor. - REORG code reorganization. Some blocks may be moved to other places, some important checks might be swapped, etc... These changes always present a risk of regression. For this reason, they should never be mixed with any bug fix nor functional change. Code is only moved as-is. Indicating the risk of breakage is highly recommended. - BUILD updates or fixes for build issues. Changes to makefiles also fall into this category. The risk of breakage should be indicated if known. It is also appreciated to indicate what platforms and/or configurations were tested after the change. - OPTIM some code was optimised. Sometimes if the regression risk is very low and the gains significant, such patches may be merged in the stable branch. Depending on the amount of code changed or replaced and the level of trust the author has in the change, the risk of regression should be indicated. - RELEASE release of a new version (development or stable). - LICENSE licensing updates (may impact distro packagers). When the patch cannot be categorized, it's best not to put any tag. This is commonly the case for new features, which development versions are mostly made of. Additionally, the importance of the patch should be indicated when known. A single upper-case word is preferred, among : - MINOR minor change, very low risk of impact. It is often the case for code additions that don't touch live code. For a bug, it generally indicates an annoyance, nothing more. - MEDIUM medium risk, may cause unexpected regressions of low importance or which may quickly be discovered. For a bug, it generally indicates something odd which requires changing the configuration in an undesired way to work around the issue. - MAJOR major risk of hidden regression. This happens when I rearrange large parts of code, when I play with timeouts, with variable initializations, etc... We should only exceptionally find such patches in stable branches. For a bug, it indicates severe reliability issues for which workarounds are identified with or without performance impacts. - CRITICAL medium-term reliability or security is at risk and workarounds, if they exist, might not always be acceptable. An upgrade is absolutely required. A maintenance release may be emitted even if only one of these bugs are fixed. Note that this tag is only used with bugs. Such patches must indicate what is the first version affected, and if known, the commit ID which introduced the issue. If this criterion doesn't apply, it's best not to put it. For instance, most doc updates and most examples or test files are just added or updated without any need to qualify a level of importance. The area the patch applies to is quite important, because some areas are known to be similar in older versions, suggesting a backport might be desirable, and conversely, some areas are known to be specific to one version. When the tag is used alone, uppercase is preferred for readability, otherwise lowercase is fine too. The following tags are suggested but not limitative : - doc documentation updates or fixes. No code is affected, no need to upgrade. These patches can also be sent right after a new feature, to document it. - examples example files. Be careful, sometimes these files are packaged. - tests regression test files. No code is affected, no need to upgrade. - init initialization code, arguments parsing, etc... - config configuration parser, mostly used when adding new config keywords - http the HTTP engine - stats the stats reporting engine as well as the stats socket CLI - checks the health checks engine (eg: when adding new checks) - acl the ACL processing core or some ACLs from other areas - peers the peer synchronization engine - listeners everything related to incoming connection settings - frontend everything related to incoming connection processing - backend everything related to LB algorithms and server farm - session session processing and flags (very sensible, be careful) - server server connection management, queueing - proxy proxy maintenance (start/stop) - log log management - poll any of the pollers - halog the halog sub-component in the contrib directory - contrib any addition to the contrib directory Other names may be invented when more precise indications are meaningful, for instance : "cookie" which indicates cookie processing in the HTTP core. Last, indicating the name of the affected file is also a good way to quickly spot changes. Many commits were already tagged with "stream_sock" or "cfgparse" for instance. It is desired that AT LEAST one of the 3 criteria tags is reported in the patch subject. Ideally, we would have the 3 most often. The two first criteria should be present before a first colon (':'). If both are present, then they should be delimited with a slash ('/'). The 3rd criterion (area) should appear next, also followed by a colon. Thus, all of the following messages are valid : Examples of messages : - DOC: document options forwardfor to logasap - DOC/MAJOR: reorganize the whole document and change indenting - BUG: stats: connection reset counters must be plain ascii, not HTML - BUG/MINOR: stats: connection reset counters must be plain ascii, not HTML - MEDIUM: checks: support multi-packet health check responses - RELEASE: Released version 1.4.2 - BUILD: stats: stdint is not present on solaris - OPTIM/MINOR: halog: make fgets parse more bytes by blocks - REORG/MEDIUM: move syscall redefinition to specific places Please do not use square brackets anymore around the tags, because they give me more work when merging patches. By default I'm asking Git to keep them but this causes trouble when patches are prefixed with the [PATCH] tag because in order not to store it, I have to hand-edit the patches. So as of now, I will ask Git to remove whatever is located between square brackets, which implies that any subject formatted the old way will have its tag stripped out. In fact, one of the only square bracket tags that still makes sense is '[RFC]' at the beginning of the subject, when you're asking for someone to review your change before getting it merged. If the patch is OK to be merged, then I can merge it as-is and the '[RFC]' tag will automatically be removed. If you don't want it to be merged at all, you can simply state it in the message, or use an alternate '[WIP]' tag ("work in progress"). The tags are not rigid, follow your intuition first, anyway I reserve the right to change them when merging the patch. It may happen that a same patch has a different tag in two distinct branches. The reason is that a bug in one branch may just be a cleanup in the other one because the code cannot be triggered. For a more efficient interaction between the mainline code and your code, I can only strongly encourage you to try the Git version control system : http://git-scm.com/ It's very fast, lightweight and lets you undo/redo your work as often as you want, without making your mistakes visible to the rest of the world. It will definitely help you contribute quality code and take other people's feedback in consideration. In order to clone the HAProxy Git repository : $ git clone http://git.1wt.eu/git/haproxy-1.4.git (stable 1.4) $ git clone http://git.1wt.eu/git/haproxy.git/ (development) If you decide to use Git for your developments, then your commit messages will have the subject line in the format described above, then the whole description of your work (mainly why you did it) will be in the body. You can directly send your commits to the mailing list, the format is convenient to read and process. -- end