Memcached (Object cache)

Memcached is a simple in-memory object store well-suited for application level caching.

See the Memcached documentation for more information.

Both Memcached and Redis can be used for application caching. As a general rule, Memcached is simpler and thus more widely supported while Redis is more robust. Upsun recommends using Redis if possible but Memcached is fully supported if an application favors that cache service.

Supported versions

You can select the major and minor version.

Patch versions are applied periodically for bug fixes and the like. When you deploy your app, you always get the latest available patches.

• 1.6
• 1.5
• 1.4

Relationship reference

For each service defined via a relationship to your application, Upsun automatically generates corresponding environment variables within your application container, in the $<RELATIONSHIP-NAME>_<SERVICE-PROPERTY> format.

Here is example information available through the service environment variables themselves, or through the PLATFORM_RELATIONSHIPS environment variable.

MEMCACHED_SERVICE=memcached
MEMCACHED_IP=123.456.78.90
MEMCACHED_HOSTNAME=azertyuiopqsdfghjklm.memcached.service._.eu-1.platformsh.site
MEMCACHED_CLUSTER=azertyuiopqsdf-main-afdwftq
MEMCACHED_HOST=memcachedcache.internal
MEMCACHED_REL=memcached
MEMCACHED_SCHEME=memcached
MEMCACHED_TYPE=memcached:1.6
MEMCACHED_PORT=11211

{
    "service": "memcached",
    "ip": "123.456.78.90",
    "hostname": "azertyuiopqsdfghjklm.memcached.service._.eu-1.platformsh.site",
    "cluster": "azertyuiopqsdf-main-afdwftq",
    "host": "memcached.internal",
    "rel": "memcached",
    "scheme": "memcached",
    "type": "memcached:1.6",
    "port": 11211
}

# Decode the built-in credentials object variable.
export RELATIONSHIPS_JSON=$(echo $PLATFORM_RELATIONSHIPS | base64 --decode)

# Set environment variables for individual credentials.
export APP_MEMCACHED_HOST="$(echo $RELATIONSHIPS_JSON | jq -r '.memcached[0].host')"

Usage example

1. Configure the service

To define the service, use the memcached type:

services:
    # The name of the service container. Must be unique within a project.
    <SERVICE_NAME>:
        type: memcached:<VERSION>

Note that changing the name of the service replaces it with a brand new service and all existing data is lost. Back up your data before changing the service.

2. Add the relationship

To define the relationship, use the following configuration:

applications:
    # The name of the app container. Must be unique within a project.
    <APP_NAME>:
        # Relationships enable access from this app to a given service.
        # The example below shows simplified configuration leveraging a default service
        # (identified from the relationship name) and a default endpoint.
        # See the Application reference for all options for defining relationships and endpoints.
        relationships:
            <SERVICE_NAME>: 
services:
    # The name of the service container. Must be unique within a project.
    <SERVICE_NAME>:
        type: memcached:<VERSION>

You can define <SERVICE_NAME> as you like, so long as it’s unique between all defined services and matches in both the application and services configuration.

The example above leverages default endpoint configuration for relationships. That is, it uses default endpoints behind-the-scenes, providing a relationship (the network address a service is accessible from) that is identical to the name of that service.

With the above definition, the application container now has access to the service via the relationship <RELATIONSHIP_NAME> and its corresponding PLATFORM_RELATIONSHIPS environment variable.

For PHP, enable the extension for the service:

applications:
    # The name of the app container. Must be unique within a project.
    <APP_NAME>:
       # PHP extensions.
        runtime:
            extensions:
                - memcached
         # Relationships enable access from this app to a given service.
        # The example below shows simplified configuration leveraging a default service
        # (identified from the relationship name) and a default endpoint.
        # See the Application reference for all options for defining relationships and endpoints.
        relationships:
            <SERVICE_NAME>: 

services:
    # The name of the service container. Must be unique within a project.
    <SERVICE_NAME>:
        type: memcached:<VERSION>

For Python, include the proper dependency:

applications:
    # The name of the app container. Must be unique within a project.
    <APP_NAME>:
       # Build dependencies per runtime.
        dependencies:
            python:
                python-memcached: '*'
         # Relationships enable access from this app to a given service.
        # The example below shows simplified configuration leveraging a default service
        # (identified from the relationship name) and a default endpoint.
        # See the Application reference for all options for defining relationships and endpoints.
        relationships:
            <SERVICE_NAME>: 

services:
    # The name of the service container. Must be unique within a project.
    <SERVICE_NAME>:
        type: memcached:<VERSION>

Example configuration

applications:
    # The name of the app container. Must be unique within a project.
    myapp:
        # Relationships enable access from this app to a given service.
        # The example below shows simplified configuration leveraging a default service
        # (identified from the relationship name) and a default endpoint.
        # See the Application reference for all options for defining relationships and endpoints.
        relationships:
            memcached: 

services:
    # The name of the service container. Must be unique within a project.
    memcached:
        type: memcached:1.6

Use in app

To use the configured service in your app, add a configuration file similar to the following to your project.

applications:
    # The name of the app container. Must be unique within a project.
    myapp:
        # The location of the application's code.
        source:
            root: "/"

        [...]

        # Relationships enable an app container's access to a service.
        relationships:
            memcached:

service:
    memcached:
        type: memcached:1.6

This configuration defines a single application (myapp), whose source code exists in the <PROJECT_ROOT>/myapp directory.
myapp has access to the influxdb service, via a relationship whose name is identical to the service name (as per default endpoint configuration for relationships).

From this, myapp can retrieve access credentials to the service through the relationship environment variables.

# Surface a Memcached connection string for use in app.
# For more information, please visit https://docs.upsun.com/development/variables.html#service-environment-variables.
export CACHE_URL="${MEMCACHED_HOST}:${MEMCACHED_PORT}"

The above file — .environment in the myapp directory — is automatically sourced by Upsun into the runtime environment, so that the variable CACHE_URL can be used within the application to connect to the service.

Note that CACHE_URL, and all Upsun service environment variables like MEMCACHEDCACHE_HOST, are environment-dependent. Unlike the build produced for a given commit, they can’t be reused across environments and only allow your app to connect to a single service instance on a single environment.

A file very similar to this is generated automatically for your when using the upsun ify command to migrate a codebase to Upsun.

Accessing Memcached directly

To access the Memcached service directly you can use netcat as Memcached doesn’t have a dedicated client tool. Assuming your Memcached relationship is named memcached, the host name MEMCACHED_HOST and port number MEMCACHED_PORT obtained from the service environment variable would be memcached.internal and 11211.
Open an SSH session and access the Memcached server as follows:

netcat memcached.internal 11211

You can obtain the complete list of available service environment variables in your app container by running upsun ssh env.

Note that the information about the relationship can change when an app is redeployed or restarted or the relationship is changed. So your apps should only rely on the service environment variables directly rather than hard coding any values.