Introduce environment variable POSTGRESQL_DEFAULT_TRANSACTION_ISOLATI…

…ON (#25013)

Signed-off-by: Florian Kamella <florian.kamella@cronn.de>

bitnami/postgresql/11/debian-11/rootfs/opt/bitnami/scripts/postgresql/run.sh

@@ -23,6 +23,10 @@ if [[ -n "${POSTGRESQL_EXTRA_FLAGS:-}" ]]; then
     flags+=("${extra_flags[@]}")
 fi
 
+if [[ -n "${POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION:-}" ]]; then
+    flags+=("-c" "default_transaction_isolation=$POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION")
+fi
+
 flags+=("$@")
 
 cmd=$(command -v postgres)

bitnami/postgresql/12/debian-11/rootfs/opt/bitnami/scripts/postgresql/run.sh

@@ -23,6 +23,10 @@ if [[ -n "${POSTGRESQL_EXTRA_FLAGS:-}" ]]; then
     flags+=("${extra_flags[@]}")
 fi
 
+if [[ -n "${POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION:-}" ]]; then
+    flags+=("-c" "default_transaction_isolation=$POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION")
+fi
+
 flags+=("$@")
 
 cmd=$(command -v postgres)

bitnami/postgresql/13/debian-11/rootfs/opt/bitnami/scripts/postgresql/run.sh

@@ -23,6 +23,10 @@ if [[ -n "${POSTGRESQL_EXTRA_FLAGS:-}" ]]; then
     flags+=("${extra_flags[@]}")
 fi
 
+if [[ -n "${POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION:-}" ]]; then
+    flags+=("-c" "default_transaction_isolation=$POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION")
+fi
+
 flags+=("$@")
 
 cmd=$(command -v postgres)

bitnami/postgresql/14/debian-11/rootfs/opt/bitnami/scripts/postgresql/run.sh

@@ -23,6 +23,10 @@ if [[ -n "${POSTGRESQL_EXTRA_FLAGS:-}" ]]; then
     flags+=("${extra_flags[@]}")
 fi
 
+if [[ -n "${POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION:-}" ]]; then
+    flags+=("-c" "default_transaction_isolation=$POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION")
+fi
+
 flags+=("$@")
 
 cmd=$(command -v postgres)

bitnami/postgresql/15/debian-11/rootfs/opt/bitnami/scripts/postgresql/run.sh

@@ -23,6 +23,10 @@ if [[ -n "${POSTGRESQL_EXTRA_FLAGS:-}" ]]; then
     flags+=("${extra_flags[@]}")
 fi
 
+if [[ -n "${POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION:-}" ]]; then
+    flags+=("-c" "default_transaction_isolation=$POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION")
+fi
+
 flags+=("$@")
 
 cmd=$(command -v postgres)

bitnami/postgresql/README.md

@@ -181,6 +181,17 @@ Passing extra command-line flags to the postgresql service command is possible t
 
 * `POSTGRESQL_EXTRA_FLAGS`: Flags to be appended to the `postgres` startup command. No defaults
 
+#### Adjusting the default transaction isolation level
+
+The default transaction isolation level in postgresql is `read committed`, the global default transaction isolation 
+level can be changed using the environment variable `POSTGRESQL_DEFAULT_TRANSACTION_ISOLATION`.
+
+Possible values are: `read uncommitted`, `read committed`, `repeatable read` or `serializable`. For more details consult 
+the documentation for `default_transaction_isolation` in https://www.postgresql.org/docs/current/runtime-config-client.html
+
+*Note: Setting `default_transaction_isolation` via `POSTGRESQL_EXTRA_FLAGS` is currently only possible for 
+transaction levels without white spaces in its name.*
+
 ### Initializing a new instance
 
 When the container is executed for the first time, it will execute the files with extensions `.sh`, `.sql` and `.sql.gz` located at `/docker-entrypoint-initdb.d`.