Install Apache Solr Server on CentOS 8

Apache Solr is an open search enterprise search software. Here, you will learn how to install Apache Solr Server on CentOS 8.

 

Table of Contents:

 

What is Solr? :

Solr (pronounced "solar") is an open-source enterprise-search platform, written in Java, from the Apache Lucene project. Solr is available to use under Apache License 2.0.

Solr major features include full-text search, hit highlighting, faceted search, real-time indexing, dynamic clustering, database integration, NoSQL features and rich document (e.g., Word, PDF) handling. Providing distributed search and index replication.

Solr is designed for scalability and fault tolerance. Solr is widely used for enterprise search and analytics use cases and has an active development community and regular releases.

Solr runs as a standalone full-text search server. It uses the Lucene Java search library at its core for full-text indexing and search, and has REST-like HTTP/XML and JSON APIs that make it usable from most popular programming languages. Solr's external configuration allows it to be tailored to many types of applications without Java coding, and it has a plugin architecture to support more advanced customization.

Solr powers the search and navigation features of many of the world's largest internet sites.

 

Environment Specification:

We are using a minimal CentOS 8 KVM machine with following specifications.

• CPU - 3.4 Ghz (2 cores)
• Memory - 2 GB
• Storage - 20 GB
• Operating System - CentOS 8.2
• Hostname - solr-01.centlinux.com
• IP Address - 192.168.116.230 /24

 

Update CentOS 8 Software Packages:

Connect with solr-01.centlinux.com as root user by using a ssh client.

By using dnf command, update software packages in your Linux server.

[root@solr-01 ~]# dnf update -y
Last metadata expiration check: 0:00:24 ago on Sun 15 Nov 2020 08:12:06 PM PKT.
Dependencies resolved.
Nothing to do.
Complete!

Our Linux operating system is already up-to-date. The output may vary on your Linux server.

Verify the Linux operating system and Kernel version.

[root@solr-01 ~]# uname -r
4.18.0-193.28.1.el8_2.x86_64
[root@solr-01 ~]# cat /etc/redhat-release
CentOS Linux release 8.2.2004 (Core)

 

Install OpenJDK on Linux Server:

Apache Solr is written in Java programming language, therefore it requires Java Development Kit (JDK) 8 or later.

OpenJDK is available in standard yum repository and can be installed easily. Alternatively, you can also install Oracle Java SE on your Linux server.

For the sake of simplicity, we are installing OpenJDK 11 on the Linux server.

[root@solr-01 ~]# dnf install -y java-11-openjdk
...
Installed:
  abattis-cantarell-fonts-0.0.25-4.el8.noarch
  adwaita-cursor-theme-3.28.0-2.el8.noarch
  adwaita-icon-theme-3.28.0-2.el8.noarch
  alsa-lib-1.2.1.2-3.el8.x86_64
  at-spi2-atk-2.26.2-1.el8.x86_64
  at-spi2-core-2.28.0-1.el8.x86_64
  atk-2.28.1-1.el8.x86_64
  avahi-libs-0.7-19.el8.x86_64
  cairo-1.15.12-3.el8.x86_64
  cairo-gobject-1.15.12-3.el8.x86_64
  colord-libs-1.4.2-1.el8.x86_64
  copy-jdk-configs-3.7-1.el8.noarch
  cups-libs-1:2.2.6-33.el8.x86_64
  dconf-0.28.0-3.el8.x86_64
  fontconfig-2.13.1-3.el8.x86_64
  fontpackages-filesystem-1.44-22.el8.noarch
  fribidi-1.0.4-8.el8.x86_64
  gdk-pixbuf2-2.36.12-5.el8.x86_64
  gdk-pixbuf2-modules-2.36.12-5.el8.x86_64
  giflib-5.1.4-3.el8.x86_64
  glib-networking-2.56.1-1.1.el8.x86_64
  graphite2-1.3.10-10.el8.x86_64
  gsettings-desktop-schemas-3.32.0-4.el8.x86_64
  gtk-update-icon-cache-3.22.30-5.el8.x86_64
  gtk3-3.22.30-5.el8.x86_64
  harfbuzz-1.7.5-3.el8.x86_64
  hicolor-icon-theme-0.17-2.el8.noarch
  jasper-libs-2.0.14-4.el8.x86_64
  java-11-openjdk-1:11.0.9.11-0.el8_2.x86_64
  java-11-openjdk-headless-1:11.0.9.11-0.el8_2.x86_64
  javapackages-filesystem-5.3.0-1.module_el8.0.0+11+5b8c10bd.noarch
  jbigkit-libs-2.1-14.el8.x86_64
  json-glib-1.4.4-1.el8.x86_64
  lcms2-2.9-2.el8.x86_64
  libX11-1.6.8-3.el8.x86_64
  libX11-common-1.6.8-3.el8.noarch
  libXau-1.0.8-13.el8.x86_64
  libXcomposite-0.4.4-14.el8.x86_64
  libXcursor-1.1.15-3.el8.x86_64
  libXdamage-1.1.4-14.el8.x86_64
  libXext-1.3.3-9.el8.x86_64
  libXfixes-5.0.3-7.el8.x86_64
  libXft-2.3.2-10.el8.x86_64
  libXi-1.7.9-7.el8.x86_64
  libXinerama-1.1.4-1.el8.x86_64
  libXrandr-1.5.1-7.el8.x86_64
  libXrender-0.9.10-7.el8.x86_64
  libXtst-1.2.3-7.el8.x86_64
  libdatrie-0.2.9-7.el8.x86_64
  libepoxy-1.5.3-1.el8.x86_64
  libfontenc-1.1.3-8.el8.x86_64
  libgusb-0.3.0-1.el8.x86_64
  libjpeg-turbo-1.5.3-10.el8.x86_64
  libmodman-2.0.1-17.el8.x86_64
  libproxy-0.4.15-5.2.el8.x86_64
  libsoup-2.62.3-1.el8.x86_64
  libthai-0.1.27-2.el8.x86_64
  libtiff-4.0.9-17.el8.x86_64
  libwayland-client-1.17.0-1.el8.x86_64
  libwayland-cursor-1.17.0-1.el8.x86_64
  libwayland-egl-1.17.0-1.el8.x86_64
  libxcb-1.13.1-1.el8.x86_64
  lksctp-tools-1.0.18-3.el8.x86_64
  lua-5.3.4-11.el8.x86_64
  pango-1.42.4-6.el8.x86_64
  pixman-0.38.4-1.el8.x86_64
  rest-0.8.1-2.el8.x86_64
  ttmkfdir-3.0.9-54.el8.x86_64
  tzdata-java-2020d-1.el8.noarch
  xorg-x11-font-utils-1:7.5-40.el8.x86_64
  xorg-x11-fonts-Type1-7.5-19.el8.noarch

Complete!

After successful installation, verify the Java version.

[root@solr-01 ~]# java -version
openjdk version "11.0.9" 2020-10-20 LTS
OpenJDK Runtime Environment 18.9 (build 11.0.9+11-LTS)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.9+11-LTS, mixed mode, sharing)

OpenJDK has been installed on Linux server.

 

Install Apache Solr on Linux Server:

You can download Apache Solr from Github or their official website.

From Solr Download Page, copy the URL of your required version of Apache Solr and then use wget command to download Solr from the copied URL.

[root@solr-01 ~]# cd /tmp
[root@solr-01 tmp]# wget https://downloads.apache.org/lucene/solr/8.7.0/solr-8.7.0.tgz
--2020-11-15 20:28:48--  https://downloads.apache.org/lucene/solr/8.7.0/solr-8.7.0.tgz
Resolving downloads.apache.org (downloads.apache.org)... 88.99.95.219, 2a01:4f8:10a:201a::2
Connecting to downloads.apache.org (downloads.apache.org)|88.99.95.219|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 200805960 (192M) [application/x-gzip]
Saving to: âsolr-8.7.0.tgzâ

solr-8.7.0.tgz    100%[===================>] 191.50M   125KB/s    in 28m 24s

2020-11-15 20:57:13 (115 KB/s) - âsolr-8.7.0.tgzâ saved [200805960/200805960]

Extract the Solr installation script from downloaded tarball as follows.

[root@solr-01 tmp]# tar xf solr-8.7.0.tgz solr-8.7.0/bin/install_solr_service.sh --strip-components=2

Now, use the extracted installation script to install Apache Solr on your Linux server.

[root@solr-01 tmp]# ./install_solr_service.sh solr-8.7.0.tgz
We recommend installing the 'lsof' command for more stable start/stop of Solr
id: âsolrâ: no such user
Creating new user: solr

Extracting solr-8.7.0.tgz to /opt


Installing symlink /opt/solr -> /opt/solr-8.7.0 ...


Installing /etc/init.d/solr script ...


Installing /etc/default/solr.in.sh ...

Service solr installed.
Customize Solr startup configuration in /etc/default/solr.in.sh
*** [WARN] *** Your open file limit is currently 1024.
 It should be set to 65000 to avoid operational disruption.
 If you no longer wish to see this warning, set SOLR_ULIMIT_CHECKS to false in your profile or solr.in.sh
*** [WARN] ***  Your Max Processes Limit is currently 3674.
 It should be set to 65000 to avoid operational disruption.
 If you no longer wish to see this warning, set SOLR_ULIMIT_CHECKS to false in your profile or solr.in.sh
NOTE: Please install lsof as this script needs it to determine if Solr is listening on port 8983.

Started Solr server on port 8983 (pid=2241). Happy searching!


Found 1 Solr nodes:

Solr process 2241 running on port 8983
Solr at http://localhost:8983/solr not online.

Don't worry about the above warnings, we will rectify them one by one.

Install lsof software package as required by the Apache Solr.

[root@solr-01 tmp]# dnf install -y lsof
Last metadata expiration check: 1:07:30 ago on Sun 15 Nov 2020 08:12:06 PM PKT.
Dependencies resolved.
================================================================================
 Package        Architecture     Version                 Repository        Size
================================================================================
Installing:
 lsof           x86_64           4.91-2.el8              BaseOS           253 k

Transaction Summary
================================================================================
Install  1 Package

Total download size: 253 k
Installed size: 630 k
Downloading Packages:
lsof-4.91-2.el8.x86_64.rpm                      114 kB/s | 253 kB     00:02
--------------------------------------------------------------------------------
Total                                            76 kB/s | 253 kB     00:03
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                        1/1
  Installing       : lsof-4.91-2.el8.x86_64                                 1/1
  Running scriptlet: lsof-4.91-2.el8.x86_64                                 1/1
  Verifying        : lsof-4.91-2.el8.x86_64                                 1/1

Installed:
  lsof-4.91-2.el8.x86_64

Complete!

Enable Apache Solr service using following Linux command.

[root@solr-01 tmp]# systemctl enable solr
solr.service is not a native service, redirecting to systemd-sysv-install.
Executing: /usr/lib/systemd/systemd-sysv-install enable solr

Verify that the Solr service is running on default port 8983.

[root@solr-01 tmp]# ss -tulpn | grep 8983
tcp    LISTEN  0       50                         *:8983                *:*      users:(("java",pid=2241,fd=153))

To rectify the warnings during startup of Apache Solr about File and Process limits. You need to define the security limits as required by the Apache Solr.

Open limits.conf file in vim editor.

solr-01 tmp]# vi /etc/security/limits.conf

And add following directives in this file.

solr   soft   nofile   65536
solr   hard   nofile   65536
solr   soft   nproc    65536
solr   hard   nproc    65536

Restart the Solr service using legacy service command. There will be no warnings this time.

[root@solr-01 tmp]# service solr restart
Sending stop command to Solr running on port 8983 ... waiting up to 180 seconds to allow Jetty process 4524 to stop gracefully.
Waiting up to 180 seconds to see Solr running on port 8983 [/]
Started Solr server on port 8983 (pid=4865). Happy searching!

Apache Solr uses default network port 8983/tcp. Therefore, you need to allow this port in Linux firewall.

[root@solr-01 tmp]# firewall-cmd --permanent --add-port=8983/tcp
success
[root@solr-01 tmp]# firewall-cmd --reload
success

Create a test collection in Apache Solr server.

[root@solr-01 tmp]# su - solr -c "/opt/solr/bin/solr create -c testcol1 -n data_driven_schema_configs"

Created new core 'testcol1'

Open URL http://192.168.116.230:8983/solr/ in a client browser.

You are now at the dashboard of the Apache Solr web UI. You can check the recently created collection by selecting it from the drop-down box in left-side pane.

 

Conclusion:

In this installation guide, you have learned how to install Apache Solr Server on CentOS 8. Have a look at Mastering Apache Solr 7.x: An expert guide to advancing, optimizing, and scaling your enterprise search by Packt Publishing.