elDoc server and dependencies upgrade guide

Contents:

1. elDoc upgrade procedure

elDoc upgrade procedure contains the following main steps:

Obtain latest release distro
Back-up current deployment (configuration files, etc)
Replace existing files with the latest versions from the release distro
Update structure of the configuration files (e.g.: eldoc.conf, elDoc-server.sh) to match the structure of the same files from the latest release

Upgrade can be performed directly to the latest version skipping upgrades to the intermediate versions (e.g.: elDoc v5.0.4 can be upgraded directly to elDoc v5.3.2).

In case target version is not a direct descendent of the currently installed version - you need to review release notes of all intermediate versions for any backward compatibility changes and follow respective post-upgrade steps (if any).

IMPORTANT: on first launch after upgrade elDoc performs database schema updates (if needed) to the current version. It is crucial to check log files (located in the \logs folder) after elDoc initial launch after upgrade and make sure no error messages are present in the upgrade log.

2. MongoDB upgrade procedure

IMPORTANT: Always consult with the official documentation published by MongoDB on upgrade to the specific versions, as this guide provides a high-level steps description only.

For your convenience links to the official MongoDB resources on performing upgrade are provided below.

Upgrade to MongoDB 4.4:

Standalone server upgrade: https://docs.mongodb.com/manual/release-notes/4.4-upgrade-standalone/
Replicaset upgrade: https://docs.mongodb.com/manual/release-notes/4.4-upgrade-replica-set/

WARNING: When upgrading a MongoDB 4.2-series deployment containing MongoDB 3.0 metadata to a 4.4-series deployment, you must upgrade to MongoDB 4.4.1 or later. You cannot successfully upgrade a deployment containing MongoDB 3.0 metadata to MongoDB 4.4.0 without serious risk of downtime.

Upgrade to MongoDB 4.2:

Standalone server upgrade: https://docs.mongodb.com/manual/release-notes/4.2-upgrade-standalone/
Replicaset upgrade: https://docs.mongodb.com/manual/release-notes/4.2-upgrade-replica-set/

Upgrade to MongoDB 4.0:

Standalone server upgrade: https://docs.mongodb.com/manual/release-notes/4.0-upgrade-standalone/
Replicaset upgrade: https://docs.mongodb.com/manual/release-notes/4.0-upgrade-replica-set/

We do recommended to performing a gradual upgrade in case target version is not a direct descendent of the currently installed version of MongoDB. E.g.: upgrade from version 3.6 to 4.4 should be performed gradually: 3.6 → 4.0 → 4.2 → 4.4.

MongoDB upgrade steps (high-level)

WARNING: Possible data loss. Always make sure you have a valid back-up of your data before proceeding with the upgrade. Standard location of the MongoDB data according to the elDoc deployment guide is: /local/mongoData directory.

The steps below describe MongoDB upgrade when it was installed using yum repository manager, considering upgrade scenario from v4.2 to v4.4:

1) Disable existing repo:

nano /etc/yum.repos.d/mongodb-org-4.2.repo

In the repo-config file set param "enabled=1" to "enabled=0"

2) Add new repo config and perform installation of the new version:

nano /etc/yum.repos.d/mongodb-org-4.4.repo

Follow the current installation guide for the remaining steps.

3) Update Feature Compatibility Version:

Once new version of the MongoDB is up and running you need to update the Feature Compatibility Version by executing the following set of commands:

mongo
use admin
db.auth("root", "XXXX")
db.adminCommand( { setFeatureCompatibilityVersion: "4.4" } )
exit

NOTE: Value of the following parameter: "{ setFeatureCompatibilityVersion: "4.4" }" equals version of the MongoDB to which upgrade was performed.

NOTE: For upgrading MongoDB installed using tarball - you need to skip steps 1 and 2 and instead follow the standard MongoDB installation procedure using tarball. Once binaries are updated and MongoDB is up and running - proceed with the step "3) Update Feature Compatibility Version" directly.

After taking all the steps above the MongoDB upgrade procedure is done.

3. Full-text search service upgrade procedure

elDoc uses Apache Solr for providing a full-text search functionality. Upgrade procedure of the Solr software is provided below.

Solr has two main folders (path provided based on the standard deployment guide):

folder with binaries: /local/solr
folder with data: /local/solrData

As a general recommendation once Solr version is upgraded it may have sense to re-build the full-text index. It means that existing index should be deleted and re-index should be initiated for the whole documents set with the newer version of the Solr server.

Apache Solr upgrade steps

The steps below describe Solr binaries update procedure only.

1) Download latest version of Apache Solr server (recommended as per Software Requirements page)

2) Execute the upgrade steps

systemctl stop mc_eldoc_cidXXX && systemctl stop solr
tar -zxvf solr-8.7.0.tgz -C /local/solr
ln -sfn /local/solr/solr-8.7.0/ /local/solr/solr
systemctl start solr && systemctl start mc_eldoc_cidXXX

The chain of commands provided above does the following: 1) stop running mongoConnector and solr services; 2) extract archive with downloaded Solr server to the defined folder; 3) cerate a symlink to the latest version of the Solr server; 4) launch solr and mongoConnector services.

After taking all the steps above the Apache Solr upgrade procedure is done.