chaomengnan/bitnami-docker-postgresql

Bitnami PostgreSQL Docker Image

What is PostgreSQL?

PostgreSQL is an object-relational database management system (ORDBMS) with an emphasis on extensibility and on standards-compliance [source].

TL;DR;

$ docker run --name postgresql bitnami/postgresql:latest

Docker Compose

$ curl -sSL https://raw.githubusercontent.com/bitnami/bitnami-docker-postgresql/master/docker-compose.yml > docker-compose.yml
$ docker-compose up -d

Why use Bitnami Images?

• Bitnami closely tracks upstream source changes and promptly publishes new versions of this image using our automated systems.
• With Bitnami images the latest bug fixes and features are available as soon as possible.
• Bitnami containers, virtual machines and cloud images use the same components and configuration approach - making it easy to switch between formats based on your project needs.
• All our images are based on minideb a minimalist Debian based container image which gives you a small base container image and the familiarity of a leading linux distribution.
• All Bitnami images available in Docker Hub are signed with Docker Content Trust (DTC). You can use DOCKER_CONTENT_TRUST=1 to verify the integrity of the images.
• Bitnami container images are released daily with the latest distribution packages available.

This CVE scan report contains a security report with all open CVEs. To get the list of actionable security issues, find the "latest" tag, click the vulnerability report link under the corresponding "Security scan" field and then select the "Only show fixable" filter on the next page.

How to deploy PostgreSQL in Kubernetes?

Deploying Bitnami applications as Helm Charts is the easiest way to get started with our applications on Kubernetes. Read more about the installation in the Bitnami PostgreSQL Chart GitHub repository.

Bitnami containers can be used with Kubeapps for deployment and management of Helm Charts in clusters.

Why use a non-root container?

Non-root container images add an extra layer of security and are generally recommended for production environments. However, because they run as a non-root user, privileged tasks are typically off-limits. Learn more about non-root containers in our docs.

Supported tags and respective Dockerfile links

NOTE: Debian 8 images have been deprecated in favor of Debian 9 images. Bitnami will not longer publish new Docker images based on Debian 8.

Learn more about the Bitnami tagging policy and the difference between rolling tags and immutable tags in our documentation page.

• 11-ol-7, 11.3.0-ol-7-r10 (11/ol-7/Dockerfile)
• 11-debian-9, 11.3.0-debian-9-r10, 11, 11.3.0, 11.3.0-r10, latest (11/debian-9/Dockerfile)
• 10-ol-7, 10.8.0-ol-7-r10 (10/ol-7/Dockerfile)
• 10-debian-9, 10.8.0-debian-9-r10, 10, 10.8.0, 10.8.0-r10 (10/debian-9/Dockerfile)
• 9.6-ol-7, 9.6.13-ol-7-r11 (9.6/ol-7/Dockerfile)
• 9.6-debian-9, 9.6.13-debian-9-r10, 9.6, 9.6.13, 9.6.13-r10 (9.6/debian-9/Dockerfile)

Subscribe to project updates by watching the bitnami/postgresql GitHub repo.

Get this image

The recommended way to get the Bitnami PostgreSQL Docker Image is to pull the prebuilt image from the Docker Hub Registry.

$ docker pull bitnami/postgresql:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the Docker Hub Registry.

$ docker pull bitnami/postgresql:[TAG]

If you wish, you can also build the image yourself.

$ docker build -t bitnami/postgresql:latest https://github.com/bitnami/bitnami-docker-postgresql.git

Persisting your database

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 path. If the mounted directory is empty, it will be initialized on the first run.

$ docker run \
    -v /path/to/postgresql-persistence:/bitnami \
    bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    volumes:
      - /path/to/postgresql-persistence:/bitnami

Connecting to other containers

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.

Using the Command Line

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.

Step 1: Create a network

$ docker network create app-tier --driver bridge

Step 2: Launch the PostgreSQL server instance

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 \
    bitnami/postgresql:latest

Step 3: Launch your PostgreSQL client instance

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 \
    bitnami/postgresql:latest psql -h postgresql-server -U postgres

Using Docker Compose

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: 'bitnami/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

Configuration

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.

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

Setting the root password on first run

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 bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    environment:
      - POSTGRESQL_PASSWORD=password123

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

Creating a database on first run

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 bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    environment:
      - POSTGRESQL_DATABASE=my_database

Creating a database user on first run

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 bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    environment:
      - POSTGRESQL_USERNAME=my_user
      - POSTGRESQL_PASSWORD=password123
      - POSTGRESQL_DATABASE=my_database

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.

Setting up a streaming replication

A Streaming replication cluster can easily be setup with the Bitnami 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.

Step 1: Create the replication master

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 \
  bitnami/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.

Step 2: Create the replication slave

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 \
  bitnami/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: 'bitnami/postgresql:latest'
    ports:
      - '5432'
    volumes:
      - 'postgresql_master_data:/bitnami'
    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
    volumes:
      - '/path/to/postgresql-persistence:/bitnami'
  postgresql-slave:
    image: 'bitnami/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

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.

Synchronous commits

By default, the slaves instances are configued 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: 'bitnami/postgresql:latest'
    ports:
      - '5432'
    volumes:
      - 'postgresql_master_data:/bitnami'
    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-slave:
    image: 'bitnami/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: 'bitnami/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.

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/

Step 1: Run the PostgreSQL image

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

$ docker run --name postgresql \
    -v /path/to/postgresql-persistence/conf/:/bitnami/postgresql/conf/ \
    bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    volumes:
      - /path/to/postgresql-persistence/conf/:/bitnami/postgresql/conf/

Step 2: Edit the configuration

Edit the configuration on your host using your favorite editor.

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

Step 3: Restart PostgreSQL

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.

Allow settings to be loaded from files other than the default postgresql.conf

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

Specifyng initdb arguments

Specifyng 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_WALDIR: Defines a custom location for the transaction log. No defaults.

$ docker run --name postgresql \
  -e POSTGRESQL_INITDB_ARGS="--data-checksums" \
  -e POSTGRESQL_INITDB_WALDIR="/bitnami/waldir" \
  bitnami/postgresql:latest

or using Docker Compose:

version: '2'

services:
  postgresql:
    image: 'bitnami/postgresql:latest'
    ports:
      - '5432:5432'
    environment:
      - POSTGRESQL_INITDB_ARGS=--data-checksums
      - POSTGRESQL_INITDB_WALDIR=/bitnami/waldir

Environment variables aliases

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

Environment Variable	Alias
POSTGRESQL_USERNAME	POSTGRES_USER
POSTGRESQL_DATABASE	POSTGRES_DB
POSTGRESQL_PASSWORD	POSTGRES_PASSWORD
POSTGRESQL_PASSWORD_FILE	POSTGRES_PASSWORD_FILE
POSTGRESQL_PORT_NUMBER	POSTGRES_PORT_NUMBER
POSTGRESQL_INITDB_ARGS	POSTGRES_INITDB_ARGS
POSTGRESQL_INITDB_WALDIR	POSTGRES_INITDB_WALDIR
POSTGRESQL_DATA_DIR	PGDATA
POSTGRESQL_REPLICATION_USER	POSTGRES_REPLICATION_USER
POSTGRESQL_REPLICATION_MODE	POSTGRES_REPLICATION_MODE
POSTGRESQL_REPLICATION_PASSWORD	POSTGRES_REPLICATION_PASSWORD
POSTGRESQL_REPLICATION_PASSWORD_FILE	POSTGRES_REPLICATION_PASSWORD_FILE
POSTGRESQL_CLUSTER_APP_NAME	POSTGRES_CLUSTER_APP_NAME
POSTGRESQL_MASTER_HOST	POSTGRES_MASTER_HOST
POSTGRESQL_MASTER_PORT_NUMBER	POSTGRES_MASTER_PORT_NUMBER
POSTGRESQL_NUM_SYNCHRONOUS_REPLICAS	POSTGRES_NUM_SYNCHRONOUS_REPLICAS
POSTGRESQL_SYNCHRONOUS_COMMIT_MODE	POSTGRES_SYNCHRONOUS_COMMIT_MODE

Logging

The Bitnami 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.

Maintenance

Upgrade this image

Bitnami provides up-to-date versions of PostgreSQL, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

Step 1: Get the updated image

$ docker pull bitnami/postgresql:latest

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

Step 2: Stop and backup the currently running container

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)

Step 3: Remove the currently running container

$ docker rm -v postgresql

or using Docker Compose:

$ docker-compose rm -v postgresql

Step 4: Run the new image

Re-create your container from the new image.

$ docker run --name postgresql bitnami/postgresql:latest

or using Docker Compose:

$ docker-compose up postgresql

Notable Changes

9.6.12-r70, 9.6.12-ol-7-r72, 10.7.0-r69, 10.7.0-ol-7-r71, 11.2.0-r69 and 11.2.0-ol-7-r71

• Decrease the size of the container. It is not necessary Node.js anymore. PostgreSQL configuration moved to bash scripts in the rootfs/ folder.
• This container is backwards compatible with the previous versions, as the mount folders remain unchanged.
• The POSTGRESQL_PASSWORD variable must be passed to the slaves so they generate the proper pg_hba.conf admission rules.

9.6.11-r66, 9.6.11-ol-7-r83, 10.6.0-r68, 10.6.0-ol-7-r83, 11.1.0-r62 and 11.1.0-ol-7-r79

• The PostgreSQL container can be configured using two sets of environment variables. For more information, check Environment variables aliases

9.6.11-r38, 10.6.0-r39 and 11.1.0-r34

• The PostgreSQL container now contains options to easily configure synchronous commits between slaves. This provides more data stability, but must be configured with caution as it also has a cost in performance. For more information, check Synchronous Commits.

9.6.9-r19 and 10.4.0-r19

• The PostgreSQL container has been migrated to a non-root user approach. Previously the container ran as the root user and the PostgreSQL daemon was started as the postgres user. From now on, both the container and the PostgreSQL daemon run as user 1001. As a consequence, the data directory must be writable by that user. You can revert this behavior by changing USER 1001 to USER root in the Dockerfile.

9.5.3-r5

• The POSTGRES_ prefix on environment variables is now replaced by POSTGRESQL_
• POSTGRES_USER parameter has been renamed to POSTGRESQL_USERNAME.
• POSTGRES_DB parameter has been renamed to POSTGRESQL_DATABASE.
• POSTGRES_MODE parameter has been renamed to POSTGRESQL_REPLICATION_MODE.

9.5.3-r0

• All volumes have been merged at /bitnami/postgresql. Now you only need to mount a single volume at /bitnami/postgresql for persistence.
• The logs are always sent to the stdout and are no longer collected in the volume.

Contributing

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.

Issues

If you encountered a problem running this container, you can file an issue. For us to provide better support, be sure to include the following information in your issue:

• Host OS and version
• Docker version (docker version)
• Output of docker info
• Version of this container (echo $BITNAMI_IMAGE_VERSION inside the container)
• The command you used to run the container, and any relevant output you saw (masking any sensitive information)

License

Copyright (c) 2015-2019 Bitnami

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

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.