PostgreSQL (Postgres) is an open source object-relational database known for reliability and data integrity. ACID-compliant, it supports foreign keys, joins, views, triggers and stored procedures.

Overview of PostgreSQL

Trademarks: The respective trademarks mentioned in this document are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

docker run --name postgresql ghcr.io/bitcompat/postgresql:latest

Warning: This quick setup is only intended for development environments. You are encouraged to change the insecure default credentials and check out the available configuration options in the Configuration section for a more secure deployment.

Non-root container images add an extra layer of security and are generally recommended for production environments.

The recommended way to get the PostgreSQL Docker Image is to pull the prebuilt image from the AWS Public ECR Gallery or from the GitHub Container Registry

docker pull ghcr.io/bitcompat/postgresql:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the GitHub Registry or the available tags in the public ECR gallery.

docker pull ghcr.io/bitcompat/postgresql:[TAG]

If you remove the container all your data and configurations will be lost, and the next time you run the image the database will be reinitialized. To avoid this loss of data, you should mount a volume that will persist even after the container is removed.

For persistence you should mount a directory at the /bitnami/postgresql path. If the mounted directory is empty, it will be initialized on the first run.

docker run \
    -v /path/to/postgresql-persistence:/bitnami/postgresql \
    ghcr.io/bitcompat/postgresql:latest

NOTE: As this is a non-root container, the mounted files and directories must have the proper permissions for the UID 1001.

Using Docker container networking, a PostgreSQL server running inside a container can easily be accessed by your application containers.

Containers attached to the same network can communicate with each other using the container name as the hostname.

In this example, we will create a PostgreSQL client instance that will connect to the server instance that is running on the same docker network as the client.

docker network create app-tier --driver bridge

Use the --network app-tier argument to the docker run command to attach the PostgreSQL container to the app-tier network.

docker run -d --name postgresql-server \
    --network app-tier \
    ghcr.io/bitcompat/postgresql:latest

Finally we create a new container instance to launch the PostgreSQL client and connect to the server created in the previous step:

docker run -it --rm \
    --network app-tier \
    ghcr.io/bitcompat/postgresql:latest psql -h postgresql-server -U postgres

When not specified, Docker Compose automatically sets up a new network and attaches all deployed services to that network. However, we will explicitly define a new bridge network named app-tier. In this example we assume that you want to connect to the PostgreSQL server from your own custom application image which is identified in the following snippet by the service name myapp.

version: '2'

networks:
  app-tier:
    driver: bridge

services:
  postgresql:
    image: ghcr.io/bitcompat/postgresql:latest
    networks:
      - app-tier
  myapp:
    image: YOUR_APPLICATION_IMAGE
    networks:
      - app-tier

IMPORTANT:

1. Please update the YOUR_APPLICATION_IMAGE_ placeholder in the above snippet with your application image
2. In your application container, use the hostname postgresql to connect to the PostgreSQL server

Launch the containers using:

docker-compose up -d

When the container is executed, it will execute the files with extension .sh located at /docker-entrypoint-preinitdb.d before initializing or starting postgresql.

In order to have your custom files inside the docker image you can mount them as a volume.

Passing extra command-line flags to the postgresql service command is possible through the following env var:

• POSTGRESQL_EXTRA_FLAGS: Flags to be appended to the postgres startup command. No defaults

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.

In order to have your custom files inside the docker image you can mount them as a volume.

In the above commands you may have noticed the use of the POSTGRESQL_PASSWORD environment variable. Passing the POSTGRESQL_PASSWORD environment variable when running the image for the first time will set the password of the postgres user to the value of POSTGRESQL_PASSWORD (or the content of the file specified in POSTGRESQL_PASSWORD_FILE).

docker run --name postgresql -e POSTGRESQL_PASSWORD=password123 ghcr.io/bitcompat/postgresql:latest

Note! The postgres user is a superuser and has full administrative access to the PostgreSQL database.

Refer to Creating a database user on first run if you want to set an unprivileged user and a password for the postgres user.

By passing the POSTGRESQL_DATABASE environment variable when running the image for the first time, a database will be created. This is useful if your application requires that a database already exists, saving you from having to manually create the database using the PostgreSQL client.

docker run --name postgresql -e POSTGRESQL_DATABASE=my_database ghcr.io/bitcompat/postgresql:latest

You can also create a restricted database user that only has permissions for the database created with the POSTGRESQL_DATABASE environment variable. To do this, provide the POSTGRESQL_USERNAME environment variable.

docker run --name postgresql -e POSTGRESQL_USERNAME=my_user -e POSTGRESQL_PASSWORD=password123 -e POSTGRESQL_DATABASE=my_database ghcr.io/bitcompat/postgresql:latest

Note! When POSTGRESQL_USERNAME is specified, the postgres user is not assigned a password and as a result you cannot login remotely to the PostgreSQL server as the postgres user. If you still want to have access with the user postgres, please set the POSTGRESQL_POSTGRES_PASSWORD environment variable (or the content of the file specified in POSTGRESQL_POSTGRES_PASSWORD_FILE).

The PostgreSQL Image comes with the pgAudit module enabled by default. Thanks to this, audit information can be enabled in the container with these environment variables:

• POSTGRESQL_PGAUDIT_LOG: Comma-separated list with different operations to audit. Find in the official pgAudit documentation the list of possible values. No defaults.
• POSTGRESQL_PGAUDIT_LOG_CATALOG: Session logging enabled in the case where all relations in a statement are in pg_catalog. No defaults.
• POSTGRESQL_LOG_CONNECTIONS: Add log entry for logins. No defaults.
• POSTGRESQL_LOG_DISCONNECTIONS: Add log entry for logouts. No defaults.
• POSTGRESQL_LOG_HOSTNAME: Log the client hostname. No defaults.
• POSTGRESQL_LOG_LINE_PREFIX: Define the format of the log entry lines. Find in the official PostgreSQL documentation the string parameters. No defaults.
• POSTGRESQL_LOG_TIMEZONE: Set the timezone for the log entry timestamp. No defaults.

The PostgreSQL Image allows configuring several parameters for the connection and session management:

• POSTGRESQL_USERNAME_CONNECTION_LIMIT: If a user different from postgres is created, set the connection limit. No defaults.
• POSTGRESQL_POSTGRES_CONNECTION_LIMIT: Set the connection limit for the postgres user. No defaults.
• POSTGRESQL_STATEMENT_TIMEOUT: Set the statement timeout. No defaults.
• POSTGRESQL_TCP_KEEPALIVES_INTERVAL: TCP keepalive interval. No defaults.
• POSTGRESQL_TCP_KEEPALIVES_IDLE: TCP keepalive idle time. No defaults.
• POSTGRESQL_TCP_KEEPALIVES_COUNT: TCP keepalive count. No defaults.

The PostgreSQL Image allows configuring the time zone for PostgreSQL with the following environment variables:

• POSTGRESQL_TIMEZONE: Sets the time zone for displaying and interpreting time stamps.
• POSTGRESQL_LOG_TIMEZONE: Sets the time zone used for timestamps written in the server log.

By default, the PostgreSQL Image generates local and md5 entries in the pg_hba.conf file. In order to adapt to any other requirements or standards, it is possible to change the pg_hba.conf file by:

• Mounting your own pg_hba.conf file in /bitnami/postgresql/conf
• Using the POSTGRESQL_PGHBA_REMOVE_FILTERS with a comma-separated list of patterns. All lines that match any of the patterns will be removed. For example, if we want to remove all local and md5 authentication (in favour of hostssl only connections, for example), set POSTGRESQL_PGHBA_REMOVE_FILTERS=local, md5.

It is possible to modify the list of libraries that PostgreSQL will preload at boot time by setting the POSTGRESQL_SHARED_PRELOAD_LIBRARIES. The default value is POSTGRESQL_SHARED_PRELOAD_LIBRARIES=pgaudit. If, for example, you want to add the pg_stat_statements library to the preload, set POSTGRESQL_SHARED_PRELOAD_LIBRARIES=pgaudit, pg_stat_statements.

A Streaming replication cluster can easily be setup with the PostgreSQL Docker Image using the following environment variables:

• POSTGRESQL_REPLICATION_MODE: Replication mode. Possible values master/slave. No defaults.
• POSTGRESQL_REPLICATION_USER: The replication user created on the master on first run. No defaults.
• POSTGRESQL_REPLICATION_PASSWORD: The replication users password. No defaults.
• POSTGRESQL_REPLICATION_PASSWORD_FILE: Path to a file that contains the replication users password. This will override the value specified in POSTGRESQL_REPLICATION_PASSWORD. No defaults.
• POSTGRESQL_MASTER_HOST: Hostname/IP of replication master (slave parameter). No defaults.
• POSTGRESQL_MASTER_PORT_NUMBER: Server port of the replication master (slave parameter). Defaults to 5432.

In a replication cluster you can have one master and zero or more slaves. When replication is enabled the master node is in read-write mode, while the slaves are in read-only mode. For best performance its advisable to limit the reads to the slaves.

The first step is to start the master.

docker run --name postgresql-master \
  -e POSTGRESQL_REPLICATION_MODE=master \
  -e POSTGRESQL_USERNAME=my_user \
  -e POSTGRESQL_PASSWORD=password123 \
  -e POSTGRESQL_DATABASE=my_database \
  -e POSTGRESQL_REPLICATION_USER=my_repl_user \
  -e POSTGRESQL_REPLICATION_PASSWORD=my_repl_password \
  ghcr.io/bitcompat/postgresql:latest

In this command we are configuring the container as the master using the POSTGRESQL_REPLICATION_MODE=master parameter. A replication user is specified using the POSTGRESQL_REPLICATION_USER and POSTGRESQL_REPLICATION_PASSWORD parameters.

Next we start a replication slave container.

docker run --name postgresql-slave \
  --link postgresql-master:master \
  -e POSTGRESQL_REPLICATION_MODE=slave \
  -e POSTGRESQL_MASTER_HOST=master \
  -e POSTGRESQL_MASTER_PORT_NUMBER=5432 \
  -e POSTGRESQL_REPLICATION_USER=my_repl_user \
  -e POSTGRESQL_REPLICATION_PASSWORD=my_repl_password \
  ghcr.io/bitcompat/postgresql:latest

In the above command the container is configured as a slave using the POSTGRESQL_REPLICATION_MODE parameter. Before the replication slave is started, the POSTGRESQL_MASTER_HOST and POSTGRESQL_MASTER_PORT_NUMBER parameters are used by the slave container to connect to the master and replicate the initial database from the master. The POSTGRESQL_REPLICATION_USER and POSTGRESQL_REPLICATION_PASSWORD credentials are used to authenticate with the master. In order to change the pg_hba.conf default settings, the slave needs to know if POSTGRESQL_PASSWORD is set.

With these two commands you now have a two node PostgreSQL master-slave streaming replication cluster up and running. You can scale the cluster by adding/removing slaves without incurring any downtime.

Note: The cluster replicates the master in its entirety, which includes all users and databases.

If the master goes down you can reconfigure a slave to act as the master and begin accepting writes by creating the trigger file /tmp/postgresql.trigger.5432. For example the following command reconfigures postgresql-slave to act as the master:

docker exec postgresql-slave touch /tmp/postgresql.trigger.5432

Note: The configuration of the other slaves in the cluster needs to be updated so that they are aware of the new master. This would require you to restart the other slaves with --link postgresql-slave:master as per our examples.

With Docker Compose the master-slave replication can be setup using:

version: '2'

services:
  postgresql-master:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432
    volumes:
      - postgresql_master_data:/bitnami/postgresql
    environment:
      - POSTGRESQL_REPLICATION_MODE=master
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_password
      - POSTGRESQL_USERNAME=my_user
      - POSTGRESQL_PASSWORD=my_password
      - POSTGRESQL_DATABASE=my_database
  postgresql-slave:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432
    depends_on:
      - postgresql-master
    environment:
      - POSTGRESQL_REPLICATION_MODE=slave
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_password
      - POSTGRESQL_MASTER_HOST=postgresql-master
      - POSTGRESQL_PASSWORD=my_password
      - POSTGRESQL_MASTER_PORT_NUMBER=5432

volumes:
  postgresql_master_data:

Scale the number of slaves using:

docker-compose up --detach --scale postgresql-master=1 --scale postgresql-slave=3

The above command scales up the number of slaves to 3. You can scale down in the same way.

Note: You should not scale up/down the number of master nodes. Always have only one master node running.

By default, the slave instances are configured with asynchronous replication. In order to guarantee more data stability (at the cost of some performance), it is possible to set synchronous commits (i.e. a transaction commit will not return success to the client until it has been written in a set of replicas) using the following environment variables.

• POSTGRESQL_SYNCHRONOUS_COMMIT_MODE: Establishes the type of synchronous commit. The available options are: on, remote_apply, remote_write, local and off. The default value is on. For more information, check the official PostgreSQL documentation.
• POSTGRESQL_NUM_SYNCHRONOUS_REPLICAS: Establishes the number of replicas that will enable synchronous replication. This number must not be above the number of slaves that you configure in the cluster.

With Docker Compose the master-slave replication with synchronous commits can be setup as follows:

version: '2'

services:
  postgresql-master:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432
    volumes:
      - postgresql_master_data:/bitnami/postgresql
    environment:
      - POSTGRESQL_REPLICATION_MODE=master
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_password
      - POSTGRESQL_USERNAME=my_user
      - POSTGRESQL_PASSWORD=my_password
      - POSTGRESQL_DATABASE=my_database
      - POSTGRESQL_SYNCHRONOUS_COMMIT_MODE=on
      - POSTGRESQL_NUM_SYNCHRONOUS_REPLICAS=1
    volumes:
      - /path/to/postgresql-persistence:/bitnami/postgresql
  postgresql-slave:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432
    depends_on:
      - postgresql-master
    environment:
      - POSTGRESQL_REPLICATION_MODE=slave
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_password
      - POSTGRESQL_MASTER_HOST=postgresql-master
      - POSTGRESQL_MASTER_PORT_NUMBER=5432
  postgresql-slave2:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432
    depends_on:
      - postgresql-master
    environment:
      - POSTGRESQL_REPLICATION_MODE=slave
      - POSTGRESQL_REPLICATION_USER=repl_user
      - POSTGRESQL_REPLICATION_PASSWORD=repl_password
      - POSTGRESQL_MASTER_HOST=postgresql-master
      - POSTGRESQL_MASTER_PORT_NUMBER=5432

In the example above, commits will need to be written to both the master and one of the slaves in order to be accepted. The other slave will continue using asynchronous replication. Check it with the following SQL query:

postgres=# select application_name as server, state,
postgres-#       sync_priority as priority, sync_state
postgres-#       from pg_stat_replication;
| server      | state     | priority | sync_state |
|-------------|-----------|----------|------------|
| walreceiver | streaming | 0        | sync       |
| walreceiver | streaming | 0        | async      |

Note: For more advanced setups, you can define different replication groups with the application_name parameter, by setting the POSTGRESQL_CLUSTER_APP_NAME environment variable.

In order to use LDAP authentication you need to enable it setting the environment variable POSTGRESQL_ENABLE_LDAP to yes.

There are two ways of setting up the LDAP configuration:

• By configuring POSTGRESQL_LDAP_URL, where you can configure all the associated parameters in the URL.
• Setting up the parameters POSTGRESQL_LDAP_xxxx independently.

The LDAP related parameters are:

• POSTGRESQL_LDAP_SERVER: IP addresses or names of the LDAP servers to connect to. Separated by spaces.
• POSTGRESQL_LDAP_PORT: Port number on the LDAP server to connect to
• POSTGRESQL_LDAP_SCHEME: Set to ldaps to use LDAPS. Default to none.
• POSTGRESQL_LDAP_TLS: Set to 1 to use TLS encryption. Default to none.
• POSTGRESQL_LDAP_PREFIX: String to prepend to the user name when forming the DN to bind. Default to none.
• POSTGRESQL_LDAP_SUFFIX: String to append to the user name when forming the DN to bind. Default to none.
• POSTGRESQL_LDAP_BASE_DN: Root DN to begin the search for the user in. Default to none.
• POSTGRESQL_LDAP_BIND_DN: DN of user to bind to LDAP. Default to none.
• POSTGRESQL_LDAP_BIND_PASSWORD: Password for the user to bind to LDAP. Default to none.
• POSTGRESQL_LDAP_SEARCH_ATTR: Attribute to match against the user name in the search. Default to none.
• POSTGRESQL_LDAP_SEARCH_FILTER: The search filter to use when doing search+bind authentication. Default to none.
• POSTGRESQL_LDAP_URL: URL to connect to, in the format: ldap[s]://host[:port]/basedn[?[attribute][?[scope][?[filter]]]] .

For more information refer to Postgresql LDAP auth configuration documentation.

PostgreSQL supports the encryption of connections using the SSL/TLS protocol. Should you desire to enable this optional feature, you may use the following environment variables to configure the application:

• POSTGRESQL_ENABLE_TLS: Whether to enable TLS for traffic or not. Defaults to no.
• POSTGRESQL_TLS_CERT_FILE: File containing the certificate file for the TLS traffic. No defaults.
• POSTGRESQL_TLS_KEY_FILE: File containing the key for certificate. No defaults.
• POSTGRESQL_TLS_CA_FILE: File containing the CA of the certificate. If provided, PostgreSQL will authenticate TLS/SSL clients by requesting them a certificate (see ref). No defaults.
• POSTGRESQL_TLS_CRL_FILE: File containing a Certificate Revocation List. No defaults.
• POSTGRESQL_TLS_PREFER_SERVER_CIPHERS: Whether to use the server's TLS cipher preferences rather than the client's. Defaults to yes.

When enabling TLS, PostgreSQL will support both standard and encrypted traffic by default, but prefer the latter. Below there are some examples on how to quickly set up TLS traffic:

$ docker run \
    -v /path/to/certs:/opt/bitnami/postgresql/certs \
    -e ALLOW_EMPTY_PASSWORD=yes \
    -e POSTGRESQL_ENABLE_TLS=yes \
    -e POSTGRESQL_TLS_CERT_FILE=/opt/bitnami/postgresql/certs/postgres.crt \
    -e POSTGRESQL_TLS_KEY_FILE=/opt/bitnami/postgresql/certs/postgres.key \
    ghcr.io/bitcompat/postgresql:latest

Alternatively, you may also provide this configuration in your custom configuration file.

The image looks for postgresql.conf file in /opt/bitnami/postgresql/conf/. You can mount a volume at /bitnami/postgresql/conf/ and copy/edit the postgresql.conf file in the /path/to/postgresql-persistence/conf/. The default configurations will be populated to the conf/ directory if it's empty.

/path/to/postgresql-persistence/conf/
└── postgresql.conf

0 directories, 1 file

As PostgreSQL image is non-root, you need to set the proper permissions to the mounted directory in your host:

sudo chown 1001:1001 /path/to/postgresql-persistence/conf/

Run the PostgreSQL image, mounting a directory from your host.

docker run --name postgresql \
    -v /path/to/postgresql-persistence/conf/:/bitnami/postgresql/conf/ \
    ghcr.io/bitcompat/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: ghcr.io/bitcompat/postgresql:latest
    ports:
      - 5432:5432
    volumes:
      - /path/to/postgresql-persistence/conf/:/bitnami/postgresql/conf/

Edit the configuration on your host using your favorite editor.

vi /path/to/postgresql-persistence/conf/postgresql.conf

After changing the configuration, restart your PostgreSQL container for changes to take effect.

docker restart postgresql

or using Docker Compose:

docker-compose restart postgresql

Refer to the server configuration manual for the complete list of configuration options.

Apart of using a custom postgresql.conf, you can include files ending in .conf from the conf.d directory in the volume at /bitnami/postgresql/conf/. For this purpose, the default postgresql.conf contains the following section:

##------------------------------------------------------------------------------
## CONFIG FILE INCLUDES
##------------------------------------------------------------------------------

## These options allow settings to be loaded from files other than the
## default postgresql.conf.

include_dir = 'conf.d'  # Include files ending in '.conf' from directory 'conf.d'

In your host, you should create the extended configuration file under the conf.d directory:

mkdir -p /path/to/postgresql-persistence/conf/conf.d/
vi /path/to/postgresql-persistence/conf/conf.d/extended.conf

If you are using your custom postgresql.conf, you should create (or uncomment) the above section in your config file, in this case the /path/to/postgresql-persistence/conf/ structure should be something like

/path/to/postgresql-persistence/conf/
├── conf.d
│   └── extended.conf
└── postgresql.conf

1 directory, 2 files

Specifying extra initdb arguments can easily be done using the following environment variables:

• POSTGRESQL_INITDB_ARGS: Specifies extra arguments for the initdb command. No defaults.
• POSTGRESQL_INITDB_WAL_DIR: Defines a custom location for the transaction log. No defaults.

docker run --name postgresql \
  -e POSTGRESQL_INITDB_ARGS="--data-checksums" \
  -e POSTGRESQL_INITDB_WAL_DIR="/bitnami/waldir" \
  ghcr.io/bitcompat/postgresql:latest

You can control the parameters used to stop postgresql in the initialization process by using:

• POSTGRESQL_PGCTLTIMEOUT that will set the timeout for the pg_ctl command.
• POSTGRESQL_SHUTDOWN_MODE that will indicate the shutdown mode used.

The Dockerfile provides two arguments to configure extra locales at build time:

• WITH_ALL_LOCALES: Enable all supported locales. Default: no
• EXTRA_LOCALES: Comma separated list of extra locales to enable. No defaults

For example, to build an image with support for the es_ES.UTF-8 UTF-8 locale, you can add the following argument to your build command:

docker build --build-arg EXTRA_LOCALES="es_ES.UTF-8 UTF-8" ...

The PostgreSQL container allows two different sets of environment variables. Please see the list of environment variable aliases in the next table:

IMPORTANT: Changing the POSTGRES_USER will not change the owner of the database that will continue being the postgres user. In order to change the database owner, please access using postgres as user ($ psql -U postgres ...) and execute the following command:

alter database POSTGRES_DATABASE owner to POSTGRES_USER;

It is possible to change the user that PostgreSQL will use to execute the init scripts. To do so, use the following environment variables:

The default toast compression is pglz, but you can modify it by setting the environment variable POSTGRES_DEFAULT_COMPRESSION with the desired value. For example: POSTGRES_DEFAULT_COMPRESSION='lz4'.

The PostgreSQL Docker image sends the container logs to the stdout. To view the logs:

docker logs postgresql

or using Docker Compose:

docker-compose logs postgresql

You can configure the containers logging driver using the --log-driver option if you wish to consume the container logs differently. In the default configuration docker uses the json-file driver.

Up-to-date versions of PostgreSQL are provided by Bitcompat project, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

docker pull ghcr.io/bitcompat/postgresql:latest

or if you're using Docker Compose, update the value of the image property to ghcr.io/bitcompat/postgresql:latest.

Stop the currently running container using the command

docker stop postgresql

or using Docker Compose:

docker-compose stop postgresql

Next, take a snapshot of the persistent volume /path/to/postgresql-persistence using:

rsync -a /path/to/postgresql-persistence /path/to/postgresql-persistence.bkp.$(date +%Y%m%d-%H.%M.%S)

docker rm -v postgresql

or using Docker Compose:

docker-compose rm -v postgresql

Re-create your container from the new image.

docker run --name postgresql ghcr.io/bitcompat/postgresql:latest

or using Docker Compose:

docker-compose up postgresql

We'd love for you to contribute to this container. You can request new features by creating an issue, or submit a pull request with your contribution.

If you encountered a problem running this container, you can file an issue.

This package is released under MIT license.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.