Connect to a Redis instance from Cloud Run functions

You can connect to a Redis instance from Cloud Run functions by using Direct VPC egress .

Setup

If you have already installed the Google Cloud CLI and have created a Redis instance, you can skip these steps.

Install the gcloud CLI and initialize:
```
 gcloud init 
```
Follow the Quickstart Guide to create a Redis instance. Take note of the zone, IP address, and port of the Redis instance.

Prepare VPC network egress for configuration

To connect to your Redis instance, your Cloud Run function must have access to the Redis instance's authorized VPC network.

To find the name of this network, run the following command:

gcloud redis instances describe INSTANCE_ID 
--region REGION 
--format "value(authorizedNetwork)"

Make a note of the network name.

Sample function

This sample function establishes a connection to a Redis instance from Cloud Run functions.

Clone the repository for your desired programming language and navigate to the folder that contains the sample code:

Go

  git 
  
 clone 
  
 https 
 : 
 //github.com/GoogleCloudPlatform/golang-samples 
 cd 
  
 golang 
 - 
 samples 
 / 
 functions 
 / 
 memorystore 
 / 
 redis

Node.js

  git 
  
 clone 
  
 https 
 : 
 //github.com/GoogleCloudPlatform/nodejs-docs-samples 
 cd 
  
 nodejs 
 - 
 docs 
 - 
 samples 
 / 
 functions 
 / 
 memorystore 
 / 
 redis

Python

  git 
 clone 
 https 
 : 
 // 
 github 
 . 
 com 
 / 
 GoogleCloudPlatform 
 / 
 python 
 - 
 docs 
 - 
 samples 
 cd 
 python 
 - 
 docs 
 - 
 samples 
 / 
 functions 
 / 
 memorystore 
 / 
 redis

The sample code increments a Redis counter every time the function is triggered:

Go

This function uses the github.com/gomodule/redigo/redis client.

  // Package visitcount provides a Cloud Function that connects 
 // to a managed Redis instance. 
 package 
  
 visitcount 
 import 
  
 ( 
  
 "errors" 
  
 "fmt" 
  
 "log" 
  
 "net/http" 
  
 "os" 
  
 "github.com/GoogleCloudPlatform/functions-framework-go/functions" 
  
 "github.com/gomodule/redigo/redis" 
 ) 
 var 
  
 redisPool 
  
 * 
 redis 
 . 
 Pool 
 func 
  
 init 
 () 
  
 { 
  
 // Register the HTTP handler with the Functions Framework 
  
 functions 
 . 
 HTTP 
 ( 
 "VisitCount" 
 , 
  
 visitCount 
 ) 
 } 
 // initializeRedis initializes and returns a connection pool 
 func 
  
 initializeRedis 
 () 
  
 ( 
 * 
 redis 
 . 
 Pool 
 , 
  
 error 
 ) 
  
 { 
  
 redisHost 
  
 := 
  
 os 
 . 
 Getenv 
 ( 
 "REDISHOST" 
 ) 
  
 if 
  
 redisHost 
  
 == 
  
 "" 
  
 { 
  
 return 
  
 nil 
 , 
  
 errors 
 . 
 New 
 ( 
 "REDISHOST must be set" 
 ) 
  
 } 
  
 redisPort 
  
 := 
  
 os 
 . 
 Getenv 
 ( 
 "REDISPORT" 
 ) 
  
 if 
  
 redisPort 
  
 == 
  
 "" 
  
 { 
  
 return 
  
 nil 
 , 
  
 errors 
 . 
 New 
 ( 
 "REDISPORT must be set" 
 ) 
  
 } 
  
 redisAddr 
  
 := 
  
 fmt 
 . 
 Sprintf 
 ( 
 "%s:%s" 
 , 
  
 redisHost 
 , 
  
 redisPort 
 ) 
  
 const 
  
 maxConnections 
  
 = 
  
 10 
  
 return 
  
& redis 
 . 
 Pool 
 { 
  
 MaxIdle 
 : 
  
 maxConnections 
 , 
  
 Dial 
 : 
  
 func 
 () 
  
 ( 
 redis 
 . 
 Conn 
 , 
  
 error 
 ) 
  
 { 
  
 c 
 , 
  
 err 
  
 := 
  
 redis 
 . 
 Dial 
 ( 
 "tcp" 
 , 
  
 redisAddr 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 nil 
 , 
  
 fmt 
 . 
 Errorf 
 ( 
 "redis.Dial: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 return 
  
 c 
 , 
  
 err 
  
 }, 
  
 }, 
  
 nil 
 } 
 // visitCount increments the visit count on the Redis instance 
 // and prints the current count in the HTTP response. 
 func 
  
 visitCount 
 ( 
 w 
  
 http 
 . 
 ResponseWriter 
 , 
  
 r 
  
 * 
 http 
 . 
 Request 
 ) 
  
 { 
  
 // Initialize connection pool on first invocation 
  
 if 
  
 redisPool 
  
 == 
  
 nil 
  
 { 
  
 // Pre-declare err to avoid shadowing redisPool 
  
 var 
  
 err 
  
 error 
  
 redisPool 
 , 
  
 err 
  
 = 
  
 initializeRedis 
 () 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Printf 
 ( 
 "initializeRedis: %v" 
 , 
  
 err 
 ) 
  
 http 
 . 
 Error 
 ( 
 w 
 , 
  
 "Error initializing connection pool" 
 , 
  
 http 
 . 
 StatusInternalServerError 
 ) 
  
 return 
  
 } 
  
 } 
  
 conn 
  
 := 
  
 redisPool 
 . 
 Get 
 () 
  
 defer 
  
 conn 
 . 
 Close 
 () 
  
 counter 
 , 
  
 err 
  
 := 
  
 redis 
 . 
 Int 
 ( 
 conn 
 . 
 Do 
 ( 
 "INCR" 
 , 
  
 "visits" 
 )) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Printf 
 ( 
 "redis.Int: %v" 
 , 
  
 err 
 ) 
  
 http 
 . 
 Error 
 ( 
 w 
 , 
  
 "Error incrementing visit count" 
 , 
  
 http 
 . 
 StatusInternalServerError 
 ) 
  
 return 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Visit count: %d" 
 , 
  
 counter 
 ) 
 }

Node.js

This function uses the redis module.

  const 
  
 functions 
  
 = 
  
 require 
 ( 
 '@google-cloud/functions-framework' 
 ); 
 const 
  
 redis 
  
 = 
  
 require 
 ( 
 'redis' 
 ); 
 const 
  
 REDISHOST 
  
 = 
  
 process 
 . 
 env 
 . 
 REDISHOST 
  
 || 
  
 'localhost' 
 ; 
 const 
  
 REDISPORT 
  
 = 
  
 process 
 . 
 env 
 . 
 REDISPORT 
  
 || 
  
 6379 
 ; 
 const 
  
 redisClient 
  
 = 
  
 redis 
 . 
 createClient 
 ({ 
  
 socket 
 : 
  
 { 
  
 host 
 : 
  
 REDISHOST 
 , 
  
 port 
 : 
  
 REDISPORT 
 , 
  
 }, 
 }); 
 redisClient 
 . 
 on 
 ( 
 'error' 
 , 
  
 err 
  
 = 
>  
 console 
 . 
 error 
 ( 
 'ERR:REDIS:' 
 , 
  
 err 
 )); 
 redisClient 
 . 
 connect 
 (); 
 functions 
 . 
 http 
 ( 
 'visitCount' 
 , 
  
 async 
  
 ( 
 req 
 , 
  
 res 
 ) 
  
 = 
>  
 { 
  
 try 
  
 { 
  
 const 
  
 response 
  
 = 
  
 await 
  
 redisClient 
 . 
 incr 
 ( 
 'visits' 
 ); 
  
 res 
 . 
 writeHead 
 ( 
 200 
 , 
  
 { 
 'Content-Type' 
 : 
  
 'text/plain' 
 }); 
  
 res 
 . 
 end 
 ( 
 `Visit count: 
 ${ 
 response 
 } 
 ` 
 ); 
  
 } 
  
 catch 
  
 ( 
 err 
 ) 
  
 { 
  
 console 
 . 
 log 
 ( 
 err 
 ); 
  
 res 
 . 
 status 
 ( 
 500 
 ). 
 send 
 ( 
 err 
 . 
 message 
 ); 
  
 } 
 });

Python

This function uses the redis-py package.

  import 
  
 os 
 import 
  
 functions_framework 
 import 
  
 redis 
 redis_host 
 = 
 os 
 . 
 environ 
 . 
 get 
 ( 
 "REDISHOST" 
 , 
 "localhost" 
 ) 
 redis_port 
 = 
 int 
 ( 
 os 
 . 
 environ 
 . 
 get 
 ( 
 "REDISPORT" 
 , 
 6379 
 )) 
 redis_client 
 = 
 redis 
 . 
 StrictRedis 
 ( 
 host 
 = 
 redis_host 
 , 
 port 
 = 
 redis_port 
 ) 
 @functions_framework 
 . 
 http 
 def 
  
 visit_count 
 ( 
 request 
 ): 
 value 
 = 
 redis_client 
 . 
 incr 
 ( 
 "visits" 
 , 
 1 
 ) 
 return 
 f 
 "Visit count: 
 { 
 value 
 } 
 "

Deploying the sample to Cloud Run functions

To deploy the function:

Copy the Dockerfile into the source directory:
```
 cp cloud_run_deployment/Dockerfile . 
```
Build a container image using Cloud Build by running the following command:
```
gcloud builds submit --tag gcr.io/ PROJECT_ID 
/visit-count
```
Deploy the container to Cloud Run by running the following command:
```
gcloud run deploy \
    --image gcr.io/ PROJECT_ID 
/visit-count \
    --allow-unauthenticated \
    --region REGION 
\
    --network NETWORK 
\
    --subnet SUBNET 
\
    --set-env-vars REDISHOST= REDIS_IP 
,REDISPORT= REDIS_PORT 
```
where:
- PROJECT_ID is your Google Cloud project's ID.
- REGION is the region where your Redis instance is located.
- NETWORK is the name of the authorized VPC network that your Redis instance is attached to.
- SUBNET is the name of your subnet. The subnet must be /26 or larger. Direct VPC egress supports RFC 1918 , RFC 6598 , and Class E IPv4 ranges.
- REDIS_IP and REDIS_PORT are the IP address and port number of your Redis instance.

After the function deployment finishes, retrieve your function's URL:

gcloud  
run  
services  
describe  
visit-count  
 \ 
--region = 
 REGION

You can see the counter increase every time you trigger the function by sending a GET request to its URL.