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tuning-scale-horizontally-cluster.rst
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r3693 | .. _scale-horizontal-cluster: | |||
Scale Horizontally / RhodeCode Cluster | ||||
-------------------------------------- | ||||
|RCE| is built in a way it support horizontal scaling across multiple machines. | ||||
There are three main pre-requisites for that: | ||||
- Shared storage that each machine can access. Using NFS or other shared storage system. | ||||
- Shared DB connection across machines. Using `MySQL`/`PostgreSQL` that each node can access. | ||||
- |RCE| user sessions and caches need to use a shared storage (e.g `Redis`_/`Memcached`) | ||||
Horizontal scaling means adding more machines or workers into your pool of | ||||
resources. Horizontally scaling |RCE| gives a huge performance increase, | ||||
especially under large traffic scenarios with a high number of requests. | ||||
This is very beneficial when |RCE| is serving many users simultaneously, | ||||
or if continuous integration servers are automatically pulling and pushing code. | ||||
It also adds High-Availability to your running system. | ||||
Cluster Overview | ||||
^^^^^^^^^^^^^^^^ | ||||
Below we'll present a configuration example that will use two separate nodes to serve | ||||
|RCE| in a load-balanced environment. The 3rd node will act as a shared storage/cache | ||||
and handle load-balancing. In addition 3rd node will be used as shared database instance. | ||||
This setup can be used both in Docker based configuration or with individual | ||||
physical/virtual machines. Using the 3rd node for Storage/Redis/PostgreSQL/Nginx is | ||||
optional. All those components can be installed on one of the two nodes used for |RCE|. | ||||
We'll use following naming for our nodes: | ||||
- `rc-node-1` (NFS, DB, Cache node) | ||||
- `rc-node-2` (Worker node1) | ||||
- `rc-node-3` (Worker node2) | ||||
Our shares NFS storage in the example is located on `/home/rcdev/storage` and | ||||
it's RW accessible on **each** node. | ||||
In this example we used certain recommended components, however many | ||||
of those can be replaced by other, in case your organization already uses them, for example: | ||||
- `MySQL`/`PostgreSQL`: Aren't replaceable and are the two only supported databases. | ||||
- `Nginx`_ on `rc-node-1` can be replaced by: `Hardware Load Balancer (F5)`, `Apache`_, `HA-Proxy` etc. | ||||
- `Nginx`_ on rc-node-2/3 acts as a reverse proxy and can be replaced by other HTTP server | ||||
acting as reverse proxy such as `Apache`_. | ||||
- `Redis`_ on `rc-node-1` can be replaced by: `Memcached` | ||||
Here's an overview what components should be installed/setup on each server in our example: | ||||
- **rc-node-1**: | ||||
- main storage acting as NFS host. | ||||
- `nginx` acting as a load-balancer. | ||||
- `postgresql-server` used for database and sessions. | ||||
- `redis-server` used for storing shared caches. | ||||
r3913 | - optionally `rabbitmq-server` or `redis` for `Celery` if used. | |||
r3693 | - optionally if `Celery` is used Enterprise/Community instance + VCSServer. | |||
- optionally mailserver that can be shared by other instances. | ||||
- optionally channelstream server to handle live communication for all instances. | ||||
- **rc-node-2/3**: | ||||
- `nginx` acting as a reverse proxy to handle requests to |RCE|. | ||||
- 1x RhodeCode Enterprise/Community instance. | ||||
- 1x VCSServer instance. | ||||
- optionally for testing connection: postgresql-client, redis-client (redis-tools). | ||||
Before we start here are few assumptions that should be fulfilled: | ||||
- make sure each node can access each other. | ||||
- make sure `Redis`_/`MySQL`/`PostgreSQL`/`RabbitMQ`_ are running on `rc-node-1` | ||||
- make sure both `rc-node-2`/`3` can access NFS storage with RW access | ||||
- make sure rc-node-2/3 can access `Redis`_/`PostgreSQL`, `MySQL` database on `rc-node-1`. | ||||
- make sure `Redis`_/Database/`RabbitMQ`_ are password protected and accessible only from rc-node-2/3. | ||||
Setup rc-node-2/3 | ||||
^^^^^^^^^^^^^^^^^ | ||||
Initially before `rc-node-1` we'll configure both nodes 2 and 3 to operate as standalone | ||||
nodes with their own hostnames. Use a default installation settings, and use | ||||
the default local addresses (127.0.0.1) to configure VCSServer and Community/Enterprise instances. | ||||
All external connectivity will be handled by the reverse proxy (`Nginx`_ in our example). | ||||
This way we can ensure each individual host works, | ||||
accepts connections, or do some operations explicitly on chosen node. | ||||
In addition this would allow use to explicitly direct certain traffic to a node, e.g | ||||
CI server will only call directly `rc-node-3`. This should be done similar to normal | ||||
installation so check out `Nginx`_/`Apache`_ configuration example to configure each host. | ||||
Each one should already connect to shared database during installation. | ||||
1) Assuming our final url will be http://rc-node-1, Configure `instances_id`, `app.base_url` | ||||
r5354 | a) On **rc-node-2** find the following settings and edit :file:`config/_shared/rhodecode.ini` | |||
r3693 | ||||
.. code-block:: ini | ||||
## required format is: *NAME- | ||||
instance_id = *rc-node-2- | ||||
app.base_url = http://rc-node-1 | ||||
r5354 | b) On **rc-node-3** find the following settings and edit :file:`config/_shared/rhodecode.ini` | |||
r3693 | ||||
.. code-block:: ini | ||||
## required format is: *NAME- | ||||
instance_id = *rc-node-3- | ||||
app.base_url = http://rc-node-1 | ||||
2) Configure `User Session` to use a shared database. Example config that should be | ||||
changed on both **rc-node-2** and **rc-node-3** . | ||||
r5354 | Edit :file:`config/_shared/rhodecode.ini` | |||
r3693 | ||||
.. code-block:: ini | ||||
#################################### | ||||
### BEAKER SESSION #### | ||||
#################################### | ||||
## Disable the default `file` sessions | ||||
#beaker.session.type = file | ||||
#beaker.session.data_dir = %(here)s/data/sessions | ||||
## use shared db based session, fast, and allows easy management over logged in users | ||||
beaker.session.type = ext:database | ||||
beaker.session.table_name = db_session | ||||
# use our rc-node-1 here | ||||
beaker.session.sa.url = postgresql://postgres:qweqwe@rc-node-1/rhodecode | ||||
beaker.session.sa.pool_recycle = 3600 | ||||
beaker.session.sa.echo = false | ||||
In addition make sure both instances use the same `session.secret` so users have | ||||
persistent sessions across nodes. Please generate other one then in this example. | ||||
.. code-block:: ini | ||||
# use a unique generated long string | ||||
beaker.session.secret = 70e116cae2274656ba7265fd860aebbd | ||||
3) Configure stored cached/archive cache to our shared NFS `rc-node-1` | ||||
.. code-block:: ini | ||||
# note the `_` prefix that allows using a directory without | ||||
# remap and rescan checking for vcs inside it. | ||||
cache_dir = /home/rcdev/storage/_cache_dir/data | ||||
# note archive cache dir is disabled by default, however if you enable | ||||
# it also needs to be shared | ||||
#archive_cache_dir = /home/rcdev/storage/_tarball_cache_dir | ||||
4) Use shared exception store. Example config that should be | ||||
changed on both **rc-node-2** and **rc-node-3**, and also for VCSServer. | ||||
r5354 | Edit :file:`config/_shared/rhodecode.ini` and | |||
r3693 | :file:`/home/{user}/.rccontrol/{vcsserver-instance-id}/vcsserver.ini` | |||
and add/change following setting. | ||||
.. code-block:: ini | ||||
exception_tracker.store_path = /home/rcdev/storage/_exception_store_data | ||||
5) Change cache backends to use `Redis`_ based caches. Below full example config | ||||
that replaces default file-based cache to shared `Redis`_ with Distributed Lock. | ||||
.. code-block:: ini | ||||
##################################### | ||||
### DOGPILE CACHE #### | ||||
##################################### | ||||
## `cache_perms` cache settings for permission tree, auth TTL. | ||||
#rc_cache.cache_perms.backend = dogpile.cache.rc.file_namespace | ||||
#rc_cache.cache_perms.expiration_time = 300 | ||||
## alternative `cache_perms` redis backend with distributed lock | ||||
rc_cache.cache_perms.backend = dogpile.cache.rc.redis | ||||
rc_cache.cache_perms.expiration_time = 300 | ||||
## redis_expiration_time needs to be greater then expiration_time | ||||
rc_cache.cache_perms.arguments.redis_expiration_time = 7200 | ||||
rc_cache.cache_perms.arguments.socket_timeout = 30 | ||||
rc_cache.cache_perms.arguments.host = rc-node-1 | ||||
rc_cache.cache_perms.arguments.password = qweqwe | ||||
rc_cache.cache_perms.arguments.port = 6379 | ||||
rc_cache.cache_perms.arguments.db = 0 | ||||
rc_cache.cache_perms.arguments.distributed_lock = true | ||||
## `cache_repo` cache settings for FileTree, Readme, RSS FEEDS | ||||
#rc_cache.cache_repo.backend = dogpile.cache.rc.file_namespace | ||||
#rc_cache.cache_repo.expiration_time = 2592000 | ||||
## alternative `cache_repo` redis backend with distributed lock | ||||
rc_cache.cache_repo.backend = dogpile.cache.rc.redis | ||||
rc_cache.cache_repo.expiration_time = 2592000 | ||||
## redis_expiration_time needs to be greater then expiration_time | ||||
rc_cache.cache_repo.arguments.redis_expiration_time = 2678400 | ||||
rc_cache.cache_repo.arguments.socket_timeout = 30 | ||||
rc_cache.cache_repo.arguments.host = rc-node-1 | ||||
rc_cache.cache_repo.arguments.password = qweqwe | ||||
rc_cache.cache_repo.arguments.port = 6379 | ||||
rc_cache.cache_repo.arguments.db = 1 | ||||
rc_cache.cache_repo.arguments.distributed_lock = true | ||||
## cache settings for SQL queries, this needs to use memory type backend | ||||
rc_cache.sql_cache_short.backend = dogpile.cache.rc.memory_lru | ||||
rc_cache.sql_cache_short.expiration_time = 30 | ||||
## `cache_repo_longterm` cache for repo object instances, this needs to use memory | ||||
## type backend as the objects kept are not pickle serializable | ||||
rc_cache.cache_repo_longterm.backend = dogpile.cache.rc.memory_lru | ||||
## by default we use 96H, this is using invalidation on push anyway | ||||
rc_cache.cache_repo_longterm.expiration_time = 345600 | ||||
## max items in LRU cache, reduce this number to save memory, and expire last used | ||||
## cached objects | ||||
rc_cache.cache_repo_longterm.max_size = 10000 | ||||
6) Configure `Nginx`_ as reverse proxy on `rc-node-2/3`: | ||||
Minimal `Nginx`_ config used: | ||||
.. code-block:: nginx | ||||
## rate limiter for certain pages to prevent brute force attacks | ||||
limit_req_zone $binary_remote_addr zone=req_limit:10m rate=1r/s; | ||||
## custom log format | ||||
log_format log_custom '$remote_addr - $remote_user [$time_local] ' | ||||
'"$request" $status $body_bytes_sent ' | ||||
'"$http_referer" "$http_user_agent" ' | ||||
'$request_time $upstream_response_time $pipe'; | ||||
server { | ||||
listen 80; | ||||
server_name rc-node-2; | ||||
#server_name rc-node-3; | ||||
access_log /var/log/nginx/rhodecode.access.log log_custom; | ||||
error_log /var/log/nginx/rhodecode.error.log; | ||||
# example of proxy.conf can be found in our docs. | ||||
include /etc/nginx/proxy.conf; | ||||
## serve static files by Nginx, recommended for performance | ||||
location /_static/rhodecode { | ||||
gzip on; | ||||
gzip_min_length 500; | ||||
gzip_proxied any; | ||||
gzip_comp_level 4; | ||||
gzip_types text/css text/javascript text/xml text/plain text/x-component application/javascript application/json application/xml application/rss+xml font/truetype font/opentype application/vnd.ms-fontobject image/svg+xml; | ||||
gzip_vary on; | ||||
gzip_disable "msie6"; | ||||
r4061 | expires 60d; | |||
r3693 | #alias /home/rcdev/.rccontrol/community-1/static; | |||
alias /home/rcdev/.rccontrol/enterprise-1/static; | ||||
} | ||||
location /_admin/login { | ||||
limit_req zone=req_limit burst=10 nodelay; | ||||
try_files $uri @rhode; | ||||
} | ||||
location / { | ||||
try_files $uri @rhode; | ||||
} | ||||
location @rhode { | ||||
# Url to running RhodeCode instance. | ||||
# This is shown as `- URL: <host>` in output from rccontrol status. | ||||
proxy_pass http://127.0.0.1:10020; | ||||
} | ||||
## custom 502 error page. Will be displayed while RhodeCode server | ||||
## is turned off | ||||
error_page 502 /502.html; | ||||
location = /502.html { | ||||
#root /home/rcdev/.rccontrol/community-1/static; | ||||
root /home/rcdev/.rccontrol/enterprise-1/static; | ||||
} | ||||
} | ||||
7) Optional: Full text search, in case you use `Whoosh` full text search we also need a | ||||
shared storage for the index. In our example our NFS is mounted at `/home/rcdev/storage` | ||||
which represents out storage so we can use the following: | ||||
.. code-block:: ini | ||||
# note the `_` prefix that allows using a directory without | ||||
# remap and rescan checking for vcs inside it. | ||||
search.location = /home/rcdev/storage/_index_data/index | ||||
.. note:: | ||||
If you use ElasticSearch it's by default shared, and simply running ES node is | ||||
by default cluster compatible. | ||||
8) Optional: If you intend to use mailing all instances need to use either a shared | ||||
mailing node, or each will use individual local mail agent. Simply put node-1/2/3 | ||||
needs to use same mailing configuration. | ||||
Setup rc-node-1 | ||||
^^^^^^^^^^^^^^^ | ||||
Configure `Nginx`_ as Load Balancer to rc-node-2/3. | ||||
Minimal `Nginx`_ example below: | ||||
.. code-block:: nginx | ||||
## define rc-cluster which contains a pool of our instances to connect to | ||||
upstream rc-cluster { | ||||
# rc-node-2/3 are stored in /etc/hosts with correct IP addresses | ||||
server rc-node-2:80; | ||||
server rc-node-3:80; | ||||
} | ||||
server { | ||||
listen 80; | ||||
server_name rc-node-1; | ||||
location / { | ||||
proxy_pass http://rc-cluster; | ||||
} | ||||
} | ||||
.. note:: | ||||
You should configure your load balancing accordingly. We recommend writing | ||||
load balancing rules that will separate regular user traffic from | ||||
automated process traffic like continuous servers or build bots. Sticky sessions | ||||
are not required. | ||||
Show which instance handles a request | ||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||||
You can easily check if load-balancing is working as expected. Visit our main node | ||||
`rc-node-1` URL which at that point should already handle incoming requests and balance | ||||
it across node-2/3. | ||||
Add a special GET param `?showrcid=1` to show current instance handling your request. | ||||
For example: visiting url `http://rc-node-1/?showrcid=1` will show, in the bottom | ||||
of the screen` cluster instance info. | ||||
e.g: `RhodeCode instance id: rc-node-3-rc-node-3-3246` | ||||
which is generated from:: | ||||
<NODE_HOSTNAME>-<INSTANCE_ID>-<WORKER_PID> | ||||
Using Celery with cluster | ||||
^^^^^^^^^^^^^^^^^^^^^^^^^ | ||||
If `Celery` is used we recommend setting also an instance of Enterprise/Community+VCSserver | ||||
r3913 | on the node that is running `RabbitMQ`_ or `Redis`_. Those instances will be used to | |||
executed async tasks on the `rc-node-1`. This is the most efficient setup. | ||||
`Celery` usually handles tasks such as sending emails, forking repositories, importing | ||||
r3693 | repositories from external location etc. Using workers on instance that has | |||
the direct access to disks used by NFS as well as email server gives noticeable | ||||
performance boost. Running local workers to the NFS storage results in faster | ||||
execution of forking large repositories or sending lots of emails. | ||||
Those instances need to be configured in the same way as for other nodes. | ||||
r3913 | The instance in rc-node-1 can be added to the cluster, but we don't recommend doing it. | |||
r3693 | For best results let it be isolated to only executing `Celery` tasks in the cluster setup. | |||
.. _Gunicorn: http://gunicorn.org/ | ||||
.. _Whoosh: https://pypi.python.org/pypi/Whoosh/ | ||||
.. _Elasticsearch: https://www.elastic.co/.. | ||||
.. _RabbitMQ: http://www.rabbitmq.com/ | ||||
.. _Nginx: http://nginx.io | ||||
.. _Apache: http://nginx.io | ||||
.. _Redis: http://redis.io | ||||