What is Memcached?
Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.
TL;DR
$ docker run --name memcached bitnami/memcached:latest
Docker Compose
$ curl -sSL https://raw.githubusercontent.com/bitnami/bitnami-docker-memcached/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 (DCT). 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 Memcached 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 Memcached 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.
Dockerfile
links
Supported tags and respective Learn more about the Bitnami tagging policy and the difference between rolling tags and immutable tags in our documentation page.
Subscribe to project updates by watching the bitnami/memcached GitHub repo.
Get this image
The recommended way to get the Bitnami Memcached Docker Image is to pull the prebuilt image from the Docker Hub Registry.
$ docker pull bitnami/memcached: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/memcached:[TAG]
If you wish, you can also build the image yourself.
docker build -t bitnami/memcached:latest 'https://github.com/bitnami/bitnami-docker-memcached.git#master:1/debian-10'
Connecting to other containers
Using Docker container networking, a Memcached 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
Step 1: Create a network
$ docker network create app-tier --driver bridge
Step 2: Launch the Memcached server instance
Use the --network app-tier
argument to the docker run
command to attach the Memcached container to the app-tier
network.
$ docker run -d --name memcached-server \
--network app-tier \
bitnami/memcached:latest
Step 3: Launch your application container
$ docker run -d --name myapp \
--network app-tier \
YOUR_APPLICATION_IMAGE
IMPORTANT:
- Please update the YOUR_APPLICATION_IMAGE_ placeholder in the above snippet with your application image
- In your application container, use the hostname
memcached-server
to connect to the Memcached server
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 Memcached 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:
memcached:
image: 'bitnami/memcached:latest'
networks:
- app-tier
myapp:
image: 'YOUR_APPLICATION_IMAGE'
networks:
- app-tier
IMPORTANT:
- Please update the YOUR_APPLICATION_IMAGE_ placeholder in the above snippet with your application image
- In your application container, use the hostname
memcached
to connect to the Memcached server
Launch the containers using:
$ docker-compose up -d
Configuration
Specify the cache size
By default, the Bitnami Memcached container will not specify any cache size and will start with Memcached defaults (64MB). You can specify a different value with the MEMCACHED_CACHE_SIZE
environment variable (in MB).
$ docker run --name memcached -e MEMCACHED_CACHE_SIZE=128 bitnami/memcached:latest
or by modifying the docker-compose.yml
file present in this repository:
services:
memcached:
...
environment:
- MEMCACHED_CACHE_SIZE=128
...
Specify maximum number of concurrent connections
By default, the Bitnami Memcached container will not specify any maximum number of concurrent connections and will start with Memcached defaults (1024 concurrent connections). You can specify a different value with the MEMCACHED_MAX_CONNECTIONS
environment variable.
$ docker run --name memcached -e MEMCACHED_MAX_CONNECTIONS=2000 bitnami/memcached:latest
or by modifying the docker-compose.yml
file present in this repository:
services:
memcached:
...
environment:
- MEMCACHED_MAX_CONNECTIONS=2000
...
Specify number of threads to process requests
By default, the Bitnami Memcached container will not specify the amount of threads for which to process requests for and will start with Memcached defaults (4 threads). You can specify a different value with the MEMCACHED_THREADS
environment variable.
$ docker run --name memcached -e MEMCACHED_THREADS=4 bitnami/memcached:latest
or by modifying the docker-compose.yml
file present in this repository:
services:
memcached:
...
environment:
- MEMCACHED_THREADS=4
...
Creating the Memcached admin user
Authentication on the Memcached server is disabled by default. To enable authentication, specify the password for the Memcached admin user using the MEMCACHED_PASSWORD
environment variable (or in the content of the file specified in MEMCACHED_PASSWORD_FILE
).
To customize the username of the Memcached admin user, which defaults to root
, the MEMCACHED_USERNAME
variable should be specified.
$ docker run --name memcached \
-e MEMCACHED_USERNAME=my_user \
-e MEMCACHED_PASSWORD=my_password \
bitnami/memcached:latest
or by modifying the docker-compose.yml
file present in this repository:
version: '2'
services:
memcached:
...
environment:
- MEMCACHED_USERNAME=my_user
- MEMCACHED_PASSWORD=my_password
...
The default value of the
MEMCACHED_USERNAME
isroot
.
Passing extra command-line flags to memcached
Passing extra command-line flags to the Memcached service command is possible by adding them as arguments to run.sh script:
$ docker run --name memcached bitnami/memcached:latest /opt/bitnami/scripts/memcached/run.sh -vvv
Alternatively, modify the docker-compose.yml
file present in this repository:
services:
memcached:
...
command: /opt/bitnami/scripts/memcached/run.sh -vvv
...
Refer to the Memcached man page for the complete list of arguments.
Using custom SASL configuration
In order to load your own SASL configuration file, you will have to make them available to the container. You can do it doing the following:
- Mounting a volume with your custom configuration
- Adding custom configuration via environment variable.
By default, when authentication is enabled the SASL configuration of Memcached is written to /opt/bitnami/memcached/sasl2/memcached.conf
file with the following content:
mech_list: plain
sasldb_path: /opt/bitnami/memcached/conf/memcachedsasldb
The /opt/bitnami/memcached/conf/memcachedsasldb
is the path to the sasldb file that contains the list of Memcached users.
Logging
The Bitnami Memcached Docker image sends the container logs to the stdout
. To view the logs:
$ docker logs memcached
or using Docker Compose:
$ docker-compose logs memcached
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 Memcached, 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/memcached:latest
or if you're using Docker Compose, update the value of the image property to
bitnami/memcached:latest
.
Step 2: Remove the currently running container
$ docker rm -v memcached
or using Docker Compose:
$ docker-compose rm -v memcached
Step 3: Run the new image
Re-create your container from the new image.
$ docker run --name memcached bitnami/memcached:latest
or using Docker Compose:
$ docker-compose up memcached
Notable Changes
1.5.18-debian-9-r13 and 1.5.19-ol-7-r1
- Fixes regression in Memcached Authentication introduced in release
1.5.18-debian-9-r6
and1.5.18-ol-7-r7
(#62).
1.5.18-debian-9-r6 and 1.5.18-ol-7-r7
- Decrease the size of the container. The configuration logic is now based on Bash scripts in the `rootfs/ folder.
- Custom SASL configuration should be mounted at
/opt/bitnami/memcached/conf/sasl2/
instead of/bitnami/memcached/conf/
. - Password for Memcached admin user can be specified in the content of the file specified in
MEMCACHED_PASSWORD_FILE
.
1.5.0-r1
- The memcached container has been migrated to a non-root container approach. Previously the container run as
root
user and the memcached daemon was started asmemcached
user. From now own, both the container and the memcached daemon run as user1001
. As a consequence, the configuration files are writable by the user running the memcached process.
1.4.25-r4
MEMCACHED_USER
parameter has been renamed toMEMCACHED_USERNAME
.
1.4.25-r0
- 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) 2015-2020 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.