fix: add references to sslmode for postgres dbs

[Chickensoupwithrice]

REL-638
raised issues that this flag did not get mentioned in the docs where a
customer wanted to use TLS. It also outlined the recommended fixes that
this commit implements.

This PR has an accompanying docs PR

Checklist

• Follow the manual testing process
• Update changelog
• Update Kubernetes update doc

Test plan

Manually test this out? Would require spinning up an RDS instance or something, but that's fine.
I'm in the process of doing so now.

[Chickensoupwithrice]

I've finally verified that this fix works. Below are screenshots showing that sslmode is passed in as an environment variable, and it's able to connect successfully to an external database.

Here is the patch I used with the password removed:

Patch file for testing

diff --git a/charts/sourcegraph/values.yaml b/charts/sourcegraph/values.yaml
index c74b21a..5b8e717 100644
--- a/charts/sourcegraph/values.yaml
+++ b/charts/sourcegraph/values.yaml
@@ -148,24 +148,24 @@ cadvisor:

codeInsightsDB:

-- Enable codeinsights-db PostgreSQL server

• enabled: true

• enabled: false
  auth:

  -- Name of existing secret to use for Code Insights credentials

  The secret must contain the keys user, password, database, host and port.

  auth.user, auth.password, etc. are ignored if this is enabled

  existingSecret: ""

  -- Sets codeinsights-db database name

• database: "postgres"

• database: "codeinsights-db"

  -- Sets codeinsights-db host

• host: "codeinsights-db"

• host: "database-1-sslmode-test.cwpsk693immt.us-west-2.rds.amazonaws.com"

  -- Sets codeinsights-db username

  user: "postgres"

  -- Sets codeinsights-db password

• password: "password"

• password: ""

  -- Sets codeinsights-db port

  port: "5432"

  -- Sets codeinsights-db SSL mode

• sslmode: "disable" # set to "require" to enable SSL

• sslmode: "require" # set to "require" to enable SSL

-- Environment variables for the codeinsights-db container

env: {}

-- Name of existing ConfigMap for codeinsights-db. It must contain a postgresql.conf key.

@@ -223,24 +223,24 @@ codeInsightsDB:

codeIntelDB:

-- Enable codeintel-db PostgreSQL server

• enabled: true

• enabled: false
  auth:

  -- Name of existing secret to use for CodeIntel credentials

  The secret must contain the keys user, password, database, host and port.

  auth.user, auth.password, etc. are ignored if this is enabled

  existingSecret: ""

  -- Sets codeintel-db database name

• database: "sg"

• database: "codeintel-db"

  -- Sets codeintel-db host

• host: "codeintel-db"

• host: "database-1-sslmode-test.cwpsk693immt.us-west-2.rds.amazonaws.com"

  -- Sets codeintel-db username

• user: "sg"

• user: "postgres"

  -- Sets codeintel-db password

• password: "password"

• password: ""

  -- Sets codeintel-db port

  port: "5432"

  -- Sets codeintel-db SSL mode

• sslmode: "disable" # set to "require" to enable SSL

• sslmode: "require" # set to "require" to enable SSL

-- Name of existing ConfigMap for codeintel-db. It must contain a postgresql.conf key

existingConfig: ""

-- Additional PostgreSQL configuration. This will override or extend our default configuration.

@@ -709,24 +709,24 @@ nodeExporter:

pgsql:

-- Enable pgsql PostgreSQL server

• enabled: true

• enabled: false
  auth:

  -- Name of existing secret to use for Postgres credentials

  The secret must contain the keys user, password, database, host and port.

  auth.user, auth.password, etc. are ignored if this is enabled

  existingSecret: ""

  -- Sets postgres database name

• database: "sg"

• database: "postgres"

  -- Sets postgres host

• host: "pgsql"

• host: "database-1-sslmode-test.cwpsk693immt.us-west-2.rds.amazonaws.com"

  -- Sets postgres username

• user: "sg"

• user: "postgres"

  -- Sets postgres password

• password: "password"

• password: ""

  -- Sets postgres port

  port: "5432"

  -- Sets postgres SSL mode

• sslmode: "disable" # set to "require" to enable SSL

• sslmode: "require" # set to "require" to enable SSL

-- Name of existing ConfigMap for pgsql. It must contain a postgresql.conf key

existingConfig: "" # Name of an existing configmap

-- Additional PostgreSQL configuration. This will override or extend our default configuration.