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diff --git a/HOWTO/OTP-PATCH-APPLY.md b/HOWTO/OTP-PATCH-APPLY.md new file mode 100644 index 0000000000..936de02d07 --- /dev/null +++ b/HOWTO/OTP-PATCH-APPLY.md @@ -0,0 +1,143 @@ +Patching OTP Applications +========================= + +Introduction +------------ + +This document describes the process of patching an existing OTP +installation with one or more Erlang/OTP applications of newer versions +than already installed. The tool `otp_patch_apply` is available for this +specific purpose. It resides in the top directory of the Erlang/OTP +source tree. + +The `otp_patch_apply` tool utilizes the [runtime_dependencies][] tag in +the [application resource file][]. This information is used to determine +if the patch can be installed in the given Erlang/OTP installation +directory. + +Read more about the [version handling][] introduced in Erlang/OTP release +17, which also describes how to determine if an installation includes one +or more patched applications. + +If you want to apply patches of multiple OTP applications that resides +in different OTP versions, you have to apply these patches in multiple +steps. It is only possible to apply multiple OTP applications from the +same OTP version at once. + +Prerequisites +------------- + +It's assumed that the reader is familiar with +[building and installing Erlang/OTP][]. To be able to patch an +application, the following must exist: + +* An Erlang/OTP installation. + +* An Erlang/OTP source tree containing the updated applications that + you want to patch into the existing Erlang/OTP installation. + +Using otp\_patch\_apply +----------------------- + +> *WARNING*: Patching applications is a one-way process. +> Create a backup of your OTP installation directory before +> proceeding. + +First of all, build the OTP source tree at `$ERL_TOP` containing +the updated applications. + +> *NOTE*: Before applying a patch you need to do a *full* build +> of OTP in the source directory. + +If you are building in `git` you first need to generate the +`configure` scripts: + + $ ./otp_build autoconf + +Configure and build all applications in OTP: + + $ configure + $ make +or + + $ ./otp_build configure + $ ./otp_build boot -a + +If you have installed documentation in the OTP installation, also +build the documentation: + + $ make docs + +After the successful build it's time to patch. The source tree directory, +the directory of the installation and the applications to patch are given +as arguments to `otp_patch_apply`. The dependencies of each application +are validated against the applications in the installation and the other +applications given as arguments. If a dependency error is detected, the +script will be aborted. + +The `otp_patch_apply` syntax: + + $ otp_patch_apply -s <Dir> -i <Dir> [-l <Dir>] [-c] [-f] [-h] \ + [-n] [-v] <App1> [... <AppN>] + + -s <Dir> -- OTP source directory that contains build results. + -i <Dir> -- OTP installation directory to patch. + -l <Dir> -- Alternative OTP source library directory path(s) + containing build results of OTP applications. + Multiple paths should be colon separated. + -c -- Cleanup (remove) old versions of applications + patched in the installation. + -f -- Force patch of application(s) even though + dependencies are not fulfilled (should only be + considered in a test environment). + -h -- Print help then exit. + -n -- Do not install documentation. + -v -- Print version then exit. + <AppX> -- Application to patch. + + Environment Variable: + ERL_LIBS -- Alternative OTP source library directory path(s) + containing build results of OTP applications. + Multiple paths should be colon separated. + +> *NOTE*: The complete build environment is required while running +> `otp_patch_apply`. + +> *NOTE*: All source directories identified by `-s` and `-l` should +> contain build results of OTP applications. + +For example, if the user wants to install patched versions of `mnesia` +and `ssl` built in `/home/me/git/otp` into the OTP installation +located in `/opt/erlang/my_otp` type + + $ otp_patch_apply -s /home/me/git/otp -i /opt/erlang/my_otp \ + mnesia ssl + +> *NOTE*: If the list of applications contains core applications, +> i.e `erts`, `kernel`, `stdlib` or `sasl`, the `Install` script in +> the patched Erlang/OTP installation must be rerun. + +The patched applications are appended to the list of installed +applications. Take a look at +`<InstallDir>/releases/OTP-REL/installed_application_versions`. + +Sanity check +------------ + +The application dependencies can be checked using the Erlang shell. +Application dependencies are verified among installed applications by +`otp_patch_apply`, but these are not necessarily those actually loaded. +By calling `system_information:sanity_check()` one can validate +dependencies among applications actually loaded. + + 1> system_information:sanity_check(). + ok + +Please take a look at the reference of [sanity_check()][] for more +information. + +[application resource file]: kernel:app +[runtime_dependencies]: kernel:app#runtime_dependencies +[building and installing Erlang/OTP]: INSTALL.md +[version handling]: ../system_principles/versions +[sanity_check()]: runtime_tools:system_information#sanity_check-0 |