Redis nodes.conf file locked? - redis

I am following this tutorial to create a Redis cluster:
http://redis.io/topics/cluster-tutorial
In this tutorial I need to run several redis-server instances on port 7000 through 7005. However after I run the first instance successfully and try to run the second instance the nodes.conf file seems to be locked and I get the following error message:
"Sorry, the cluster configuration file nodes.conf is already used by a different Redis Cluster node. Please make sure that different nodes use different cluster configuration files."
Do I need a separate nodes.conf for every server instance? Or do I need a separate redis-server executable in each instance directory and run it from there?

The tutorial suggests you to use separated folders for each instance configuration, so each instance will also generate the nodes.conf on its own folder.
Create a redis.conf file inside each of the directories, from 7000 to
7005.
You need to have the .conf files on separated folders for each instance, and the executable must be ran from that folders.
Assuming you have the redis-server on /tmp/redis-cluster/, and the redis.conf on each /tmp/redis-cluster/700x folder:
cd /tmp/redis-cluster/7000
../redis-server ./redis.conf
This way the nodes.conf will be generated on the current folder 7000.
Note that you must first issue a cd to change the current directory, and from that folder execute the redis-server that is one folder up (../)

Related

Redis .conf file running problem for slave redis instance

The problem is my Windows 10 does not understand redis commands. I downlaoded and installed on D/Program Files/Redis my cli and server .msi files.
I run with command:
redis-server D:/Program Files/Redis/redis-slave.windows.conf
and expect to get an instance on redis slave with configuration provided in course in .conf file but ger error:
Invalid argument during startup: Failed to open the .conf file: Files/Redis/redis-slave.windows.conf CWD=D:\Program Files\Redis
and the problem is not in wrong configuration because I can copy default .conf redis file and it is the same
Another problem - but not so important as above to me -- but similar when I try to run a cluster Windows 10 does not know how to open this file. I run command:
D:\Program Files\Redis2\redis-7.0.4\utils\create-cluster>./create-cluster start
and receive windows where I need to choose a program to run this file but does not seen it in your MacOS case, anyway this create-cluster file does not have extension so I do not know what to do to make it run

How configure multiple Redis instances on Debian

I've got a Debian server running Redis and I'd like to run a second copy using a different port. There are plenty of guides explaining how to do it on Ubuntu and other flavours of Linux but I'm having a hard time translating those to Debian.
So far I've created a copy of the /etc/redis/redis.conf and have renamed it /etc/redis/redis_6380.conf. In the new file I've changed the name of the PID file, location of the log file, the listening port (to 3680) so that they do not conflict with the existing instance of Redis.
The problem I have is knowing which changes to make so that systemd can start the new instance.
I've made a duplicate of /lib/systemd/system/redis-server.service and called it redis-server-6380.service and have changed the EXECStart and PIDFile lines to point to the new files:
ExecStart=/usr/bin/redis-server /etc/redis/redis_6380.conf
PIDFile=/var/run/redis/redis-server_6380.pid
Doing:
systemctl enable redis-server-6380.service
results in:
Failed to enable unit: File /etc/systemd/system/redis.service already exists and is a symlink to /lib/systemd/system/redis-server.service
How do I fix this ? I'm guessing that I've missed out a vital step but I'm not that familiar with configuring systemd supervised processes on Debian.
The end of the redis-server unit file would say:
[Install]
WantedBy=multi-user.target
Alias=redis.service
Either remove that Alias, or make sure it would be unique.
Also: make sure your Redis instances would have their own database and log files.

how to import dump.rdb file to redis local server

Hi I'm trying to import the dump.rdb file to my local redis I'm using ubuntu 14.04,
I've tried this solutions :
backup data from server using SAVE command
Locate the location to put the dump.rdb file
Since I install redis using this tutorial, so I copy the imported dump.rdb to my redis root directory, and then started the redis server like this :
src/redis-server
and then connect the client using :
src/redis-cli
But When I tried to get the all keys using KEYS * I got (empty list or set) where did I go wrong? I've been playing this for hours, any help? thank you
If you have followed the steps correctly it will work fine.
1) Make sure the imported dump.rdb contains your data
2) Stop the redis server
3) copy the file in the correct directory (inside redis bin directory)
parallel to redis-server.
4) make sure you have the same data, that is copied. (bcz possibilites
that if your server is still running, it will replace your dump.rdb).
5) start your redis server you will surely find the values.
If it still doesn't work. Check the dbfilename in your redis.conf file.
It must be dbfilename dump.rdb. If there is a change in the location place it in the correct directory.
Hope this works.
I found the problem in my step, in the documentation quick start redis :
Using src/redis-server Redis was started without any explicit configuration file so I need to start the server with the configuration file to make the server read my dump.rdb file like this :
src/redis-server redis.conf
now I can get all the imported data.

Changing permissions of added file to a Docker volume

In the Docker best practices guide it states:
You are strongly encouraged to use VOLUME for any mutable and/or user-serviceable parts of your image.
And by looking at the source code for e.g. the cpuguy83/nagios image this can clearly be seen done, as everything from nagios to apache config directories are made available as volumes.
However, looking at the same image the apache service (and cgi-scripts for nagios) are run as the nagios user by default. So now I'm in a pickle, as I can't seem to figure how to add my own config files in order to e.g. define more hosts for nagios monitoring. I've tried:
FROM cpuguy83/nagios
ADD my_custom_config.cfg /opt/nagios/etc/conf.d/
RUN chown nagios: /opt/nagios/etc/conf.d/my_custom_config.cfg
CMD ["/opt/local/bin/start_nagios"]
I build as normal, and try to run it with docker run -d -p 8000:80 <image_hash>, however I get the following error:
Error: Cannot open config file '/opt/nagios/etc/conf.d/my_custom_config.cfg' for reading: Permission denied
And sure enough, the permissions in the folder looks like (whist the apache process runs as nagios):
# ls -l /opt/nagios/etc/conf.d/
-rw-rw---- 1 root root 861 Jan 5 13:43 my_custom_config.cfg
Now, this has been answered before (why doesn't chown work in Dockerfile), but no proper solution other than "change the original Dockerfile" has been proposed.
To be honest, I think there's some core concept here I haven't grasped (as I can't see the point of declaring config directories as VOLUME nor running services as anything other than root) - so provided a Dockerfile as above (which follows Docker best practices by adding multiple volumes) is the solution/problem:
To change NAGIOS_USER/APACHE_RUN_USER to 'root' and run everything as root?
To remove the VOLUME declarations in the Dockerfile for nagios?
Other approaches?
How would you extend the nagios dockerfile above with your own config file?
Since you are adding your own my_custom_config.cfg file directly into the container at build time just change the permissions of the my_custom_config.cfg file on your host machine and then build your image using docker build. The host machine permissions are copied into the container image.

How to recover redis data from snapshot(rdb file) copied from another machine?

I transferred my redis snapshot (dump.rdb file) using scp to a remote server. I need to run a redis server on this remote and recover the data from the dump.rdb file. How can I do that?
For databases where the appendonly flag is set to no, you can do the following:
Stop Redis (because Redis overwrites the current rdb file when it exits).
Copy your backup rdb file to the Redis working directory (this is the dir option in your Redis config). Also, make sure your backup filename matches the dbfilename config option.
Start Redis.
If, on the other hand, you need to restore an rdb file to the appendonly database, you should do something along the lines of:
Stop Redis (because Redis overwrites the current rdb file when it exits).
Copy your backup rdb file to the Redis working directory (this is the dir option in your Redis config). Also, make sure your backup filename matches the dbfilename config option.
Change the Redis config appendonly flag to no (otherwise Redis will ignore your rdb file when it starts).
Start Redis.
Run redis-cli BGREWRITEAOF to create a new appendonly file.
Restore the Redis config appendonly flag to yes.
Specifically, this is the relevant bit of documentation from the Redis config file comments:
# Note that you can have both the async dumps and the append only file if you
# like (you have to comment the "save" statements above to disable the dumps).
# >> Still if appendonly mode is enabled Redis will load the data from the
# >> log file at startup ignoring the dump.rdb file.
There is nothing specific to do. Just install the redis server on the new machine, and edit the configuration file. You just need to change the following parameters to point to the location of the dump file you have just copied.
# The filename where to dump the DB
dbfilename mydump.rdb
# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# Also the Append Only File will be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir /data/mydirectory/
Finally, the redis server can be started in the normal way.
Assuming that you run Redis 2.6 or higher, your Redis snapshot filename is dump.rdb, and it exists in the directory /home/user/dbs, the following command would do the trick:
redis-server --dbfilename dump.rdb --dir /home/user/dbs
Relevant section from the official documentation: Passing arguments via the command line
Or you can:
Stop your redis server / instance, eg., service redis6379 stop
Copy the dump.rdb file to the right location, eg., cp /path/to/dump-6379.rdb /var/lib/redis/dump-6379.rdb. Give it the right permissions (user:group should be redis:redis and mode 644)
Start your redis server / instance, eg., service redis6379 start
It is important that you stop the redis server before copying the file to the right location, because Redis saves a snapshot before terminating, so it will replace your file.
Besides, you might want to back up the existing dump.rdb file first.
I would like to add here a tiny detail that did not get mentioned and I will not use config file but instead specify everything in the command line.
When both mydump.rdb and appendonly.aof files are specified when starting redis-server, it will be the appendonly.aof file that wins such that the data from appendonly.aof gets loaded. For example:
redis-server --dbfilename mydump001.rdb --dir /data --appendonly yes
The above start invocation will use the /dir location to find the presence of mydump001.rdb or appendonly.aof files. In this case, redis-server will load the contents from appendonly.aof. If appendonly.aof does not exists, it will create an empty /data/appendonly.aof and the redis-server will be empty.
If you want to load a specific dump file, you can do:
redis-server --dbfilename mydump001.rdb --dir /data
I added this answer coz it is not obvious which is which. In the presence of 2 backup files, and this is often not mentioned.
start redis on your second server, like so:
$ > redis-server /path/to/my/redis/configuration/file/redis.conf
when redis starts, it will find your rdb file because it will look for the name
and file path in the configuration file (redis.conf) that you supply when
start the redis server, as above.
to supply the file name and path, just edit two lines in the redis.conf file template (supplied in the root directory of the redis source. Save your revised version as redis.conf in the directory location that you supplied upon starting the server.
You will find the settings you need in the redis.conf template in the source top-level directory, at lines 127 and 137 (redis version 2.6.9).
# The filename where to dump the DB
dbfilename dump.rdb
# The working directory
dir ./
as you can see, defaults are provided for both settings
so just change the first of these two lines (127) to identify your rdb file
and in the second (137) substitute the default "./" for the actual file path
for your snapshot rdb file; save the redis.conf with your changes, and start redis passing in this new conf file.
This solution work with redis-cluster, but should work too with redis.
Install this dependencie https://github.com/sripathikrishnan/redis-rdb-tools
pip install rdbtools python-lzf
after that execute this
rdb -c protocol /path/to/dump.rdb | redis-cli -h host -p port --pipe
If this is a cluster, the port should the master`s port.
try set appendonly no.
In My case, *.aof file was empty(0 byte), must set appendonly=no then make it load the dump.rdb
Install https://github.com/leonchen83/redis-rdb-cli
rmt -s ./your-dump.rdb -m redis://host:port -r