From 85e2821400dafd4afc4b75da331d2fd2129c5238 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Mon, 4 Dec 2017 18:11:24 +0000 Subject: Add s6-rc-format-upgrade --- .gitignore | 1 + doc/index.html | 6 ++ doc/s6-rc-format-upgrade.html | 125 ++++++++++++++++++++++++++++++++ package/deps.mak | 2 + package/targets.mak | 3 +- src/s6-rc/deps-exe/s6-rc-format-upgrade | 2 + src/s6-rc/s6-rc-format-upgrade.c | 70 ++++++++++++++++++ src/s6-rc/s6-rc-update.c | 19 +---- 8 files changed, 211 insertions(+), 17 deletions(-) create mode 100644 doc/s6-rc-format-upgrade.html create mode 100644 src/s6-rc/deps-exe/s6-rc-format-upgrade create mode 100644 src/s6-rc/s6-rc-format-upgrade.c diff --git a/.gitignore b/.gitignore index 9713499..d06e759 100644 --- a/.gitignore +++ b/.gitignore @@ -13,3 +13,4 @@ /s6-rc-update /s6-rc-fdholder-filler /s6-rc-oneshot-run +/s6-rc-format-upgrade diff --git a/doc/index.html b/doc/index.html index ee06542..9ce7128 100644 --- a/doc/index.html +++ b/doc/index.html @@ -111,6 +111,12 @@ the previous versions of s6-rc and the current one.

Upgrading from earlier s6-rc database formats

+ +

The s6-rc-format-upgrade program

Programs used internally

s6-rc: the s6-rc-format-upgrade program

+s6-rc
+Software
+skarnet.org +

The s6-rc-format-upgrade program

+ s6-rc-format-upgrade is a program that is normally used +very rarely: when the s6-rc package is upgraded, some +services are currently managed with s6-rc, and the database +format has changed. This program transitions a live directory +using a database with the old s6-rc format (the one being +replaced) so that it uses a database with the new s6-rc format. +

+ The point is to ensure a smooth transition between different +versions of s6-rc without needing a reboot. +

+ s6-rc-format-upgrade is very different from +s6-rc-update and does not +duplicate its functionality: +

s6-rc-update updates a +live directory to use a different compiled database, +compiled from a different source, where services may have +changed, be renamed, etc. But it can only handle databases +with the format that it knows - the format created by the +s6-rc-compile binary that +comes in the same package as s6-rc-update.
s6-rc-format-upgrade is the opposite: it cannot handle +service changes, it can only update a live directory to use +a compiled database corresponding to the same source +as the compiled database the live directory is currently +using. But it will replace an obsolete compiled database with +a compiled database that uses the new format (provided both +compiled databases come from the same source, and have just been +produced by invocation of different versions of +s6-rc-compile), ensuring the +s6-rc installation can live through database format changes.

Interface

+     s6-rc-format-upgrade [ -v verbosity ] [ -l live ] [ -t timeout ] [ -b ] newcompiled
+

newcompiled must be an absolute path.
s6-rc-format-upgrade expects to find a compiled service database +with the new format in compiled
newcompiled must be compiled from +the same source database as the current compiled database currently +being used by live. +
s6-rc-format-upgrade then updates the live directory in live +so it uses newcompiled as its compiled database.
On success, it exits 0.

Options

-v verbosity : be more or less +verbose. Default is 1.
-t timeout : if all +operations have not completed after timeout +milliseconds, complain and exit 1.
-l live : Work with the live state in +the live directory. Default is +/run/s6-rc. The default can be changed at compile time by +giving the --livedir=live option to +./configure.
-b : blocking lock. If live is currently +being used by another program, s6-rc-format-upgrade will wait until that +other program has released its lock on the directory, then proceed. +By default, s6-rc-format-upgrade fails with an error message if the live +directory is currently in use.

Typical usage

+ s6-rc-format-upgrade is only necessary when the database format +changes, which only happens when s6-rc's major version number +(the third number from the right) changes. The correct order of +operations is then the following: +

Make sure your current compiled database is up-to-date +with your source database. If it's not, update it, by invoking +the s6-rc-compile and +s6-rc-update binaries from your +old s6-rc installation, the ones that +understand the old format.
From the same source, compile a new database with the new format, +using the s6-rc-compile binary +from the new s6-rc package.
Update your live directories with this new database, using +s6-rc-format-upgrade.
You can now remove the old databases, and delete the old +s6-rc package.

+#include +#include +#include +#include +#include +#include +#include + +#define USAGE "s6-rc-format-upgrade [ -v verbosity ] [ -t timeout ] [ -l live ] [ -b ] newdb" +#define dieusage() strerr_dieusage(100, USAGE) + +static unsigned int verbosity = 1 ; + + + /* This function will change if format changes become heavier */ + +static inline void update_livedir (char const *live, char const *newcompiled, tain_t const *deadline) +{ + size_t livelen = strlen(live) ; + char cfn[livelen + 10] ; + memcpy(cfn, live, livelen) ; + memcpy(cfn + livelen, "/compiled", 10) ; + if (!atomic_symlink(newcompiled, cfn, PROG)) + strerr_diefu4sys(111, "atomic_symlink ", cfn, " to ", newcompiled) ; +} + + +int main (int argc, char const *const *argv, char const *const *envp) +{ + tain_t deadline ; + char const *live = S6RC_LIVE_BASE ; + int blocking = 0 ; + int livelock ; + PROG = "s6-rc-format-upgrade" ; + { + unsigned int t = 0 ; + subgetopt_t l = SUBGETOPT_ZERO ; + for (;;) + { + int opt = subgetopt_r(argc, argv, "v:t:l:b", &l) ; + if (opt == -1) break ; + switch (opt) + { + case 'v' : if (!uint0_scan(l.arg, &verbosity)) dieusage() ; break ; + case 't' : if (!uint0_scan(l.arg, &t)) dieusage() ; break ; + case 'l' : live = l.arg ; break ; + case 'b' : blocking = 1 ; break ; + default : dieusage() ; + } + } + argc -= l.ind ; argv += l.ind ; + if (t) tain_from_millisecs(&deadline, t) ; + else deadline = tain_infinite_relative ; + } + if (!argc) dieusage() ; + if (argv[0][0] != '/') + strerr_dief2x(100, argv[0], " is not an absolute path") ; + + tain_now_g() ; + tain_add_g(&deadline, &deadline) ; + + if (!s6rc_lock(live, 2, &livelock, 0, 0, 0, blocking)) + strerr_diefu2sys(111, "take lock on ", live) ; + + update_livedir(live, argv[0], &deadline) ; + return 0 ; +} diff --git a/src/s6-rc/s6-rc-update.c b/src/s6-rc/s6-rc-update.c index dc3806b..0313f1e 100644 --- a/src/s6-rc/s6-rc-update.c +++ b/src/s6-rc/s6-rc-update.c @@ -1,6 +1,5 @@ /* ISC license. */ -#include /* Solaris doesn't know mkdtemp() is POSIX */ #include #include #include @@ -21,7 +20,6 @@ #include #include #include -#include #include #include #include @@ -516,31 +514,20 @@ static void fill_tfmt (char *tfmt, tain_t const *deadline) static inline void update_fdholder (s6rc_db_t const *olddb, unsigned char const *oldstate, s6rc_db_t const *newdb, unsigned char const *newstate, unsigned int const *invimage, char const *const *envp, tain_t const *deadline) { - int fdsocket ; s6_fdholder_t a = S6_FDHOLDER_ZERO ; char fnsocket[livelen + sizeof("/servicedirs/" S6RC_FDHOLDER "/s")] ; if (!(newstate[1] & 1)) return ; memcpy(fnsocket, live, livelen) ; memcpy(fnsocket + livelen, "/servicedirs/" S6RC_FDHOLDER "/s", sizeof("/servicedirs/" S6RC_FDHOLDER "/s")) ; - fdsocket = ipc_stream_nb() ; - if (fdsocket < 0) goto hammer ; - if (!ipc_timed_connect_g(fdsocket, fnsocket, deadline)) - { - if (errno == ETIMEDOUT) strerr_dief1x(2, "timed out during s6rc-fdholder update") ; - else goto closehammer ; - } - s6_fdholder_init(&a, fdsocket) ; + if (!s6_fdholder_start_g(&a, fnsocket, deadline)) goto hammer ; if (!delete_unused_pipes(&a, olddb, oldstate, deadline)) goto freehammer ; if (!rename_pipes(&a, olddb, newdb, newstate, invimage, deadline)) goto freehammer ; if (!create_new_pipes(&a, newdb, newstate, deadline)) goto freehammer ; - s6_fdholder_free(&a) ; - close(fdsocket) ; + s6_fdholder_end(&a) ; return ; freehammer: - s6_fdholder_free(&a) ; - closehammer: - close(fdsocket) ; + s6_fdholder_end(&a) ; hammer: if (verbosity) strerr_warnwu1x("live update s6rc-fdholder - restarting it") ; { -- cgit v1.3.1