Bitbucket: Convert From Standalone ElasticSearch to Embedded OpenSearch

At work I maintain random stacks of software, and sometimes help people with other stacks that they maintain. Recently I was asked to help bring a Atlassian Bitbucket stack up to date. In the past Atlassian always included a built-in ElasticSearch (ES) server. This was used to index code in Bitbucket and allow searching. It’s not a hard requirement for the server to function, but important for user experience.

When an environment moves from Bitbucket Server to Bitbucket enterprise you are supposed to go to a standalone ES over the embedded one for performance. I don’t know if people elsewhere commonly do this, but the stacks I have seen have just continued to use the embedded version. Admittedly, these are smaller instances; at scale I would understand that. That was until recently, when due to a licensing change Atlassian could no longer embed a up to date ElasticSearch. For a while they decided the best way to move forward was to keep bundling the one from before the licensing change (I think 7.10).

This works until you have an infosec team use Nessus and find you have an out-of-date ES sitting around when 7.16, or the 8.0 branch are out. From all that, this one stack had moved to a standalone ES cluster. We also now had to install the Atlassian security plugin into ES; this was not a simple task, and this plugin only supports a few versions of ES, none of which were current. At least then we are at a BETTER spot with security.

Now fast forward a few months of this mess going on, and Atlassian moved Bitbucket from ElasticSearch to OpenSearch. OpenSearch is a fork of ElasticSearch at version 7.10.2 from Amazon to get around these new licensing terms. Normally if you were still using the embedded version of ES, when you did your next upgrade of Bitbucket it would move you to OpenSearch. Because this stack had already moved to standalone instance it did not migrate over. We are now in the worst of both worlds, off the supported path, and can’t get back on it. If you search the Atlassian documentation there are guides on how to move to a standalone version, but not back. A big catch I found was they use default passwords in the embedded version, that are not easy to find, which lead you making it hard to migrate back.

Migrating Back

Below are some notes I have on migrating back. Hopefully they help someone.

There are two main folders we will work in, one is your Atlassian Bitbucket installation folder for this version, I will call it %atlassian-install%, then there is your Bitbucket data folder that moves between your versions, with your upgrades, we will call that %bitbucket-home%. (Note: I did all this on Linux, but I am calling the variables that because it is easy)

Default %atlassian-install% is /opt/atlassian/bitbucket/7.21.7, or your current version. Default %bitbucket-home% is /var/atlassian/application-data/bitbucket, but I tend to move that to /opt.

Under %atlassian-install%/opensearch/plugins/opensearch-security/securityconfig/internal_user.yml is the details Bitbucket needs to connect to this OpenSearch instance. The default password is “bitbucket-changeit”. To create a new hash of a password, the following file needs to be given execute privileges and does not come with that on Linux; %atlassian-install%/opensearch/plugins/opensearch-security/tools/hash.sh .

Go into %bitbucket-home%/shared/bitbucket.properties if you have one, this file is created as you migrate between versions or databases; and remove any legacy elasticsearch username/password/url settings. For example: plugin.search.elasticsearch.baseurl or plugin.search.config.baseurl as shown in the documentation. The properties file overrides settings you have in the instance/database. You may have a SystemD service file to automatically start Bitbucket, this file has the start-bitbucket.sh file starting with -ns or --no-search to run a standalone instance, remove the no search option.

Now start Bitbucket and go to Administration -> Troubleshooting and support tools -> System Information, you will see Search failed to connect. Go to Administration -> Server settings, then enter your new search information there. If you just removed ElasticSearch, and started OpenSearch with the server, all you have to do is make sure the port is right, by default 7992 I believe, then make sure the username is “bitbucket” and the password is “bitbucket-changeit”. If you get a connection error it may be that you have to setup a TLS trust between Bitbucket and Opensearch, but that is outside the scope of this guide.

Below is the default %bitbucket-home%/shared/search/config/opensearch.yml

cluster.name: bitbucket_search
node:
  name: bitbucket_bundled

network.host: _local_
discovery.type: single-node

path:
  logs: ${BITBUCKET_HOME}/log/search
  data: ${BITBUCKET_HOME}/shared/search/data

action.auto_create_index: false

http.port: 7992
transport.tcp.port: 7993

# The OpenSearch security plugin stores its configuration in an index in the cluster itself. On startup if the
# security index doesn't exist yet, sitting this to true will cause the security plugin to read the yml files and
# configure the index using the contents of the files.
plugins.security.allow_default_init_securityindex: true

# Using the yml files with default initialisation, we create a bitbucket user and give it the all_access in-built role.
# However, access to the REST API is disabled by default even for the all_access role so we need to explicitly give
# it permission here so that the bitbucket user can access the OpenSearch REST API.
plugins.security.restapi.roles_enabled: ["all_access"]

# Mandatory TLS setup for transport layer
plugins.security.authcz.admin_dn:
  - CN=BITBUCKET
plugins.security.ssl.transport.enforce_hostname_verification: false
plugins.security.ssl.transport.pemcert_filepath: bitbucket.pem
plugins.security.ssl.transport.pemkey_filepath: bitbucket-key.pem
plugins.security.ssl.transport.pemtrustedcas_filepath: root-ca.pem

# Logs audit events to bitbucket_search_server.json
plugins.security.audit.type: log4j
plugins.security.audit.config.log4j.logger_name: audit
plugins.security.audit.config.log4j.level: INFO

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