This also depends on the nbthread count, so it must only be performed after
parsing the whole config file. As a side effect, this removes some code
duplication between servers and server-templates.
This must be backported to 1.9.
With variable connection limits, it's not possible to accurately determine
whether the mux is still in use by comparing usage and max to be equal due
to the fact that one determines the capacity and the other one takes care
of the context. This can cause some connections to be dropped before they
reach their stream ID limit.
It seems it could also cause some connections to be terminated with
streams still alive if the limit was reduced to match the newly computed
avail_streams() value, though this cannot yet happen with existing muxes.
Instead let's switch to usage reports and simply check whether connections
are both unused and available before adding them to the idle list.
This should be backported to 1.9.
Make "bind" keywork be supported in "peers" sections.
All "bind" settings are supported on this line.
Add "default-bind" option to parse the binding options excepted the bind address.
Do not parse anymore the bind address for local peers on "server" lines.
Do not use anymore list_for_each_entry() to set the "peers" section
listener parameters because there is only one listener by "peers" section.
May be backported to 1.5 and newer.
In session, don't keep an infinite number of connection that can idle.
Add a new frontend parameter, "max-session-srv-conns" to set a max number,
with a default value of 5.
Now we try to synchronously push updates as they come using the new rdv
point, so that the call to the server update function from the main poll
loop is not needed anymore.
It further reduces the apparent latency in the health checks as the response
time almost always appears as 0 ms, resulting in a slightly higher check rate
of ~1960 conn/s. Despite this, the CPU consumption has slightly dropped again
to ~32% for the same test.
The only trick is that the checks code is built with a bit of recursivity
because srv_update_status() calls server_recalc_eweight(), and the latter
needs to signal srv_update_status() in case of updates. Thus we added an
extra argument to this function to indicate whether or not it must
propagate updates (no if it comes from srv_update_status).
Now all the code used to manipulate chunks uses a struct buffer instead.
The functions are still called "chunk*", and some of them will progressively
move to the generic buffer handling code as they are cleaned up.
srv_set_fqdn() may be called with the DNS lock already held, but tries to
lock it anyway. So, add a new parameter to let it know if it was already
locked or not;
This is a huge patch with many changes, all about the DNS. Initially, the idea
was to update the DNS part to ease the threads support integration. But quickly,
I started to refactor some parts. And after several iterations, it was
impossible for me to commit the different parts atomically. So, instead of
adding tens of patches, often reworking the same parts, it was easier to merge
all my changes in a uniq patch. Here are all changes made on the DNS.
First, the DNS initialization has been refactored. The DNS configuration parsing
remains untouched, in cfgparse.c. But all checks have been moved in a post-check
callback. In the function dns_finalize_config, for each resolvers, the
nameservers configuration is tested and the task used to manage DNS resolutions
is created. The links between the backend's servers and the resolvers are also
created at this step. Here no connection are kept alive. So there is no needs
anymore to reopen them after HAProxy fork. Connections used to send DNS queries
will be opened on demand.
Then, the way DNS requesters are linked to a DNS resolution has been
reworked. The resolution used by a requester is now referenced into the
dns_requester structure and the resolution pointers in server and dns_srvrq
structures have been removed. wait and curr list of requesters, for a DNS
resolution, have been replaced by a uniq list. And Finally, the way a requester
is removed from a DNS resolution has been simplified. Now everything is done in
dns_unlink_resolution.
srv_set_fqdn function has been simplified. Now, there is only 1 way to set the
server's FQDN, independently it is done by the CLI or when a SRV record is
resolved.
The static DNS resolutions pool has been replaced by a dynamoc pool. The part
has been modified by Baptiste Assmann.
The way the DNS resolutions are triggered by the task or by a health-check has
been totally refactored. Now, all timeouts are respected. Especially
hold.valid. The default frequency to wake up a resolvers is now configurable
using "timeout resolve" parameter.
Now, as documented, as long as invalid repsonses are received, we really wait
all name servers responses before retrying.
As far as possible, resources allocated during DNS configuration parsing are
releases when HAProxy is shutdown.
Beside all these changes, the code has been cleaned to ease code review and the
doc has been updated.
Fix regression introduced by commit:
'MAJOR: servers: propagate server status changes asynchronously.'
The building of the log line was re-worked to be done at the
postponed point without lack of data.
[wt: this only affects 1.8-dev, no backport needed]
In order to prepare multi-thread development, code was re-worked
to propagate changes asynchronoulsy.
Servers with pending status changes are registered in a list
and this one is processed and emptied only once 'run poll' loop.
Operational status changes are performed before administrative
status changes.
In a case of multiple operational status change or admin status
change in the same 'run poll' loop iteration, those changes are
merged to reach only the targeted status.
The server state and weight was reworked to handle
"pending" values updated by checks/CLI/LUA/agent.
These values are commited to be propagated to the
LB stack.
In further dev related to multi-thread, the commit
will be handled into a sync point.
Pending values are named using the prefix 'next_'
Current values used by the LB stack are named 'cur_'
This patch fixes a bug where some servers managed by SRV record query
types never ever recover from a "no resolution" status.
The problem is due to a wrong function called when breaking the
server/resolution (A/AAAA) relationship: this is performed when a server's SRV
record disappear from the SRV response.
Make it so for each server, instead of specifying a hostname, one can use
a SRV label.
When doing so, haproxy will first resolve the SRV label, then use the
resulting hostnames, as well as port and weight (priority is ignored right
now), to each server using the SRV label.
It is resolved periodically, and any server disappearing from the SRV records
will be removed, and any server appearing will be added, assuming there're
free servers in haproxy.
As DNS servers may not return all IPs in one answer, we want to cache the
previous entries. Those entries are removed when considered obsolete, which
happens when the IP hasn't been returned by the DNS server for a time
defined in the "hold obsolete" parameter of the resolver section. The default
is 30s.
This patch is a major upgrade of the internal run-time DNS resolver in
HAProxy and it brings the following 2 main changes:
1. DNS resolution task
Up to now, DNS resolution was triggered by the health check task.
From now, DNS resolution task is autonomous. It is started by HAProxy
right after the scheduler is available and it is woken either when a
network IO occurs for one of its nameserver or when a timeout is
matched.
From now, this means we can enable DNS resolution for a server without
enabling health checking.
2. Introduction of a dns_requester structure
Up to now, DNS resolution was purposely made for resolving server
hostnames.
The idea, is to ensure that any HAProxy internal object should be able
to trigger a DNS resolution. For this purpose, 2 things has to be done:
- clean up the DNS code from the server structure (this was already
quite clean actually) and clean up the server's callbacks from
manipulating too much DNS resolution
- create an agnostic structure which allows linking a DNS resolution
and a requester of any type (using obj_type enum)
3. Manage requesters through queues
Up to now, there was an uniq relationship between a resolution and it's
owner (aka the requester now). It's a shame, because in some cases,
multiple objects may share the same hostname and may benefit from a
resolution being performed by a third party.
This patch introduces the notion of queues, which are basically lists of
either currently running resolution or waiting ones.
The resolutions are now available as a pool, which belongs to the resolvers.
The pool has has a default size of 64 resolutions per resolvers and is
allocated at configuration parsing.
Prior this patch, the DNS responses were stored in a pre-allocated
memory area (allocated at HAProxy's startup).
The problem is that this memory is erased for each new DNS responses
received and processed.
This patch removes the global memory allocation (which was not thread
safe by the way) and introduces a storage of the dns response in the
struct
resolution.
The memory in the struct resolution is also reserved at start up and is
thread safe, since each resolution structure will have its own memory
area.
For now, we simply store the response and use it atomically per
response per server.
In the process of breaking links between dns_* functions and other
structures (mainly server and a bit of resolution), the function
dns_get_ip_from_response needs to be reworked: it now can call
"callback" functions based on resolution's owner type to allow modifying
the way the response is processed.
For now, main purpose of the callback function is to check that an IP
address is not already affected to an element of the same type.
For now, only server type has a callback.
This adds a new "dynamic" keyword for the cookie option. If set, a cookie
will be generated for each server (assuming one isn't already provided on
the "server" line), from the IP of the server, the TCP port, and a secret
key provided. To provide the secret key, a new keyword as been added,
"dynamic-cookie-key", for backends.
Example :
backend bk_web
balance roundrobin
dynamic-cookie-key "bla"
cookie WEBSRV insert dynamic
server s1 127.0.0.1:80 check
server s2 192.168.56.1:80 check
This is a first step to be able to dynamically add and remove servers,
without modifying the configuration file, and still have all the load
balancers redirect the traffic to the right server.
Provide a way to generate session cookies, based on the IP address of the
server, the TCP port, and a secret key provided.
We get this when Lua is disabled, just a missing include.
In file included from src/queue.c:18:0:
include/proto/server.h:51:39: warning: 'struct appctx' declared inside parameter list [enabled by default]
Several CLI commands require a server, so let's have a function to
look this one up and prepare the appropriate error message and the
appctx's state in case of failure.
This new setting supports a comma-delimited list of methods used to
resolve the server's FQDN to an IP address. Currently supported methods
are "libc" (use the regular libc's resolver) and "last" (use the last
known valid address found in the state file).
The list is implemented in a 32-bit integer, because each init-addr
method only requires 3 bits. The last one must always be SRV_IADDR_END
(0), allowing to store up to 10 methods in a single 32 bit integer.
Note: the doc is provided at the end of this series.
It will be important to help debugging some DNS resolution issues to
know why a server was marked down, so let's make the function support
a 3rd argument with an indication of the reason. Passing NULL will keep
the message as-is.
Server addresses are not resolved anymore upon the first pass so that we
don't fail if an address cannot be resolved by the libc. Instead they are
processed all at once after the configuration is fully loaded, by the new
function srv_init_addr(). This function only acts on the server's address
if this address uses an FQDN, which appears in server->hostname.
For now the function does two things, to followup with HAProxy's historical
default behavior:
1. apply server IP address found in server-state file if runtime DNS
resolution is enabled for this server
2. use the DNS resolver provided by the libc
If none of the 2 options above can find an IP address, then an error is
returned.
All of this will be needed to support the new server parameter "init-addr".
For now, the biggest user-visible change is that all server resolution errors
are dumped at once instead of causing a startup failure one by one.
Right now there is an issue with the way the maintenance flags are
propagated upon startup. They are not propagate, just copied from the
tracked server. This implies that depending on the server's order, some
tracking servers may not be marked down. For example this configuration
does not work as expected :
server s1 1.1.1.1:8000 track s2
server s2 1.1.1.1:8000 track s3
server s3 1.1.1.1:8000 track s4
server s4 wtap:8000 check inter 1s disabled
It results in s1/s2 being up, and s3/s4 being down, while all of them
should be down.
The only clean way to process this is to run through all "root" servers
(those not tracking any other server), and to propagate their state down
to all their trackers. This is the same algorithm used to propagate the
state changes. It has to be done both to compute the IDRAIN flag and the
IMAINT flag. However, doing so requires that tracking servers are not
marked as inherited maintenance anymore while parsing the configuration
(and given that it is wrong, better drop it).
This fix also addresses another side effect of the bug above which is
that the IDRAIN/IMAINT flags are stored in the state files, and if
restored while the tracked server doesn't have the equivalent flag,
the servers may end up in a situation where it's impossible to remove
these flags. For example in the configuration above, after removing
"disabled" on server s4, the other servers would have remained down,
and not anymore with this fix. Similarly, the combination of IMAINT
or IDRAIN with their respective forced modes was not accepted on
reload, which is wrong as well.
This bug has been present at least since 1.5, maybe even 1.4 (it came
with tracking support). The fix needs to be backported there, though
the srv-state parts are irrelevant.
This commit relies on previous patch to silence warnings on startup.
New DNS response parser function which turn the DNS response from a
network buffer into a DNS structure, much easier for later analysis
by upper layer.
Memory is pre-allocated at start-up in a chunk dedicated to DNS
response store.
New error code to report a wrong number of queries in a DNS response.
This function can replace update_server_addr() where the need to change the
server's port as well as the IP address is required.
It performs some validation before performing each type of change.
This is very useful in complex architecture systems where HAproxy
is balancing DB connections for example. We want to keep the maxconn
high in order to avoid issues with queueing on the LB level when
there is slowness on another part of the system. Example is a case of
an architecture where each thread opens multiple DB connections, which
if get stuck in queue cause a snowball effect (old connections aren't
closed, new ones cannot be established). These connections are mostly
idle and the DB server has no problem handling thousands of them.
Allowing us to dynamically set maxconn depending on the backend usage
(LA, CPU, memory, etc.) enables us to have high maxconn for situations
like above, but lowering it in case there are real issues where the
backend servers become overloaded (cache issues, DB gets hit hard).
the function server_parse_addr_change_request() contain an hardcoded
updater source "stats command". this function can be called from other
sources than the "stats command", so this patch make this argument
generic.
The commit 87b096 renames the functions srv_shutdown_backup_sessions()
and srv_shutdown_sessions() to srv_shutdown_backup_streams() and
srv_shutdown_streams().
The header file <proto/servers.h> does not repport these changes.
This bug should be repported in the 1.6 branch, even if it is useless
because new dev are frozen.
This directive gives HAProxy the ability to use the either the global
server-state-file directive or a local one using server-state-file-name to
load server states.
The state can be saved right before the reload by the init script, using
the "show servers state" command on the stats socket redirecting output into
a file.
This patch introduces three new functions which can be used to find a
server in a farm using different server information:
- server unique id (srv->puid)
- server name
- find best match using either name or unique id
When performing best matching, the following applies:
- use the server name first (if provided)
- use the server id if provided
in any case, the function can update the caller about mismatches
encountered.
Ability to change a server IP address during HAProxy run time.
For now this is provided via function update_server_addr() which
currently is not called.
A log is emitted on each change. For now we do it inconditionally,
but later we'll want to do it only on certain circumstances, which
explains why the logging block is enclosed in if(1).
If a source file includes proto/server.h twice or more, redefinition errors will
be triggered for such inline functions as server_throttle_rate(),
server_is_draining(), srv_adm_set_maint() and so on. Just move #endif directive
to the end of file to solve this issue.
Signed-off-by: Godbach <nylzhaowei@gmail.com>
This patch adds support for a new "drain" mode. So now we have 3 admin
modes for a server :
- READY
- DRAIN
- MAINT
The drain mode disables load balancing but leaves the server up. It can
coexist with maint, except that maint has precedence. It is also inherited
from tracked servers, so just like maint, it's represented with 2 bits.
New functions were designed to set/clear each flag and to propagate the
changes to tracking servers when relevant, and to log the changes. Existing
functions srv_set_adm_maint() and srv_set_adm_ready() were replaced to make
use of the new functions.
Currently the drain mode is not yet used, however the whole logic was tested
with all combinations of set/clear of both flags in various orders to catch
all corner cases.
This function was taken from check_set_server_drain(). It does not
consider health checks at all and only sets a server to stopping
provided it's not in maintenance and is not currently stopped. The
resulting state will be STOPPING. The state change is propagated
to tracked servers.
For now the function is not used, but the goal is to split health
checks status from server status and to be able to change a server's
state regardless of health checks statuses.
This function was taken from check_set_server_up(). It does not consider
health checks at all and only sets a server up provided it's not in
maintenance. The resulting state may be either RUNNING or STARTING
depending on the presence of a slowstart or not. The state change is
propagated to tracked servers.
For now the function is not used, but the goal is to split health
checks status from server status and to be able to change a server's
state regardless of health checks statuses.
This function was extracted from check_set_server_down(). In only
manipulates the server state and does not consider the health checks
at all, nor does it modify their status. It takes a reason message to
report in logs, however it passes NULL when recursing through the
trackers chain.
For now the function is not used, but the goal is to split health
checks status from server status and to be able to change a server's
state regardless of health checks statuses.
srv_adm_append_status() was renamed srv_append_status() since it's no
more dedicated to maintenance mode. It now supports a reason which if
not null is appended to the output string.
This change now involves a new flag SRV_ADMF_IMAINT to note that the
maintenance status of a server is inherited from another server. Thus,
we know at each server level in the chain if it's running, in forced
maintenance or in a maintenance status because it tracks another server,
or even in both states.
Disabling a server propagates this flag down to other servers. Enabling
a server flushes the flag down. A server becomes up again once both of
its flags are cleared.
Two new functions "srv_adm_set_maint()" and "srv_adm_set_ready()" are used to
manipulate this maintenance status. They're used by the CLI and the stats
page.
Now the stats page always says "MAINT" instead of "MAINT(via)" and it's
only the chk/down field which reports "via x/y" when the status is
inherited from another server, but it doesn't say it when a server was
forced into maintenance. The CSV output indicates "MAINT (via x/y)"
instead of only "MAINT(via)". This is the most accurate representation.
One important thing is that now entering/leaving maintenance for a
tracking server correctly follows the state of the tracked server.
Checks.c has become a total mess. A number of proxy or server maintenance
and queue management functions were put there probably because they were
used there, but that makes the code untouchable. And that's without saying
that their names does not always relate to what they really do!
So let's do a first pass by moving these ones :
- set_backend_down() => backend.c
- redistribute_pending() => queue.c:pendconn_redistribute()
- check_for_pending() => queue.c:pendconn_grab_from_px()
- shutdown_sessions => server.c:srv_shutdown_sessions()
- shutdown_backup_sessions => server.c:srv_shutdown_backup_sessions()
All of them were moved at once.
This flag is only a copy of (srv->uweight == 0), so better get rid of
it to reduce some of the confusion that remains in the code, and use
a simple function to return this state based on this weight instead.
The cfgparse.c file becomes huge, and a large part of it comes from the
server keyword parser. Since the configuration is a bit more modular now,
move this parser to server.c.
This patch also moves the check of the "server" keyword earlier in the
supported keywords list, resulting in a slightly faster config parsing
for configs with large numbers of servers (about 10%).
No functional change was made, only the code was moved.
